The Arid Soils of the Balikh Basin (Syria)

THE ARID SOILS OF THE BALIKH BASIN (SYRIA)

M.A. MULDERS ERRATA

THE ARID SOILS OF THE BALIKH BASIN (SYRIA). M.A. MULDERS, 1969

page 21, line 2 from bottom: read: 1, 4 instead of: 14 page 81, line 1 from top: read: x instead of: x % K page 103t Fig» 19: read: phytoliths instead of: pytoliths page 121, profile 51, 40-100 cm: read: clay instead of: silty clay page 125, profile 26, 40-115 cm: read: silt loam instead of: clay loam page 127, profile 38, 105-150 cm: read: clay instead of: silty loam page 127, profile 42, 14-40 cm: read: silty clay loam instead of: silt loam page 127, profile 42, 4O-6O cm: read: silt loam instead of: clay loam page 138, 16IV, texture: read: 81,5# sand, 14,4% silt instead of: 14,42! sand, 81.3% silt page 163, add: A and P values (quantimet), magnification of thin sections 105x THE ARID SOILS OF THE BALIKH BASIN (SYEIA).

M.A. MULDERS, 19Ô9 page 18, Table 2: read: mm instead of: min page 80, Fig. 16: read: kaolinite instead of: kaolite page 84, Table 21 : read: Kaolinite instead of: Kaolonite page 99, line 17 from top: read: at instead of: a page 106, line 20 from bottom: read: moist instead of: most page 109t line 8 from bottom: read: recognizable instead of: recognisable page 115» Fig. 20, legend: oblique lines : topsoil, 0 - 30 cm horizontal lines : deeper subsoil, 60 - 100 cm page 159» line 6 from top: read: are instead of: is 5Y

THE ARID SOILS OF THE BAUKH BASIN (SYRIA)

37? THE ARID SOILS OF THE BALIKH BASIN (SYRIA)

PROEFSCHRIFT

TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE WISKUNDE EN NATUURWETENSCHAPPEN AAN DE RIJKS- UNIVERSITEIT TE UTRECHT, OP GEZAG VAN DE RECTOR MAGNIFICUS, PROF.DR. J. LANJOUW, VOLGENS BESLUIT VAN DE SENAAT IN HET OPENBAAR TE VERDEDIGEN OP MAANDAG 31 MAART 1969 DES NAMIDDAGS TE 2.30 UUR

DOOR

MICHEL ADRIANUS MULDERS

GEBOREN OP 21 AUGUSTUS 1941 TE BERGEN OP ZOOM

Scanned from original by ISRIC - World Soil Information, as ICSU World Data Centre for Soils. The purpose is to make a safe depository for endangered documents and to make the accrued information available for consultation, following Fair Use Guidelines. Every effort is taken to respect Copyright of the materials within the archives where the identification of the Copyright holder is clear and, where feasible, to contact the originators. For questions please contact soil.isriccawur.nl indicating the item reference number concerned.

1969 DRUKKERIJ BRONDER-OFFSET N.V. ROTTERDAM PROMOTOR: PROF. DR. IR. F. A. VAN BAREN Aan de nagedachtenis van mijn vader Aan mijn moeder Aan mijn vrouw THE ARID SOILS OF THE BALIKH BASIN (SYRIA).

PREFACE

The Balikh Basin is situated in the Jazirah in the northern part of Syria. The location of the area and most places referred to in the text are shown on a locality map (appendix I). The area under consideration is a part of the region where the Euphrates Project under direction of the G. O. E. P. (General Organization of the Euphrates Project) is in operation. During the years 1965 and 1966, the author was a co-operator of the soil survey team carrying out a soil suitability mapping. This volume represents a study of soil forming factors and the genesis of the soils occurring in the area. For the treatment of this subject the genetic concept of soil given by Dokuchaiev in 1870 was of great influence. Quoting the "Soil classification, a comprehensive system, 7th approximation" (United States Department of Agriculture, 1960): Soil according to Dokuchaiev consists of independent natural bodies, each with a unique morphology resulting from a unique combination of climate, living matter, parent rock materials, relief and time. The morphology of each soil, as expressed in its profile reflects the combined effects of the particular set of genetic factors responsible for its development. Therefore, the factors of importance for soil formation are dealt with in detail. These are: climate, geology, morphology, hydrology, mineralogy of the soil material, flora, fauna and land use. Also sedimentological processes should be examined in detail before evaluation of soil forming dynamics. Marbut (quoted by the U.S. soil classification, see above) wrote in 1913: Important in the classification of soils is to recognize not only the character of the rock from which the material has been derived but also the agencies which have acted in the transportation and deposition of the soil material and the changes which have taken place since its deposition. The soils were classified according to the U.S. Soil classification, 7th Approximation with supplements and a soil map scale 1:50. 000 was constructed (appendices III and IV). Morphology and micromorphology were studied being of fundamental importance for evaluation of soil genetic processes. ACKNOWLEDGEMENTS

It is a pleasant and proper duty for me to make personal acknowledgements to all people who were involved in my professional training at the universities of Groningen and Utrecht. Especially I like to thank Professor Dr. Ph. H. Kuenen, Professor Dr. M. G. Rutten, Professor Dr. D. J. Doeglas and Professor Dr. Ir. R.W. van Bemmelen. In particular I am extremely indebted to Dr. Ir. F. A. Van Baren, professor of soil science at the State University of Utrecht, who promoted the completion of this thesis in every way. His criticism and suggestions were of great value for this study. The author feels greatly indebted to Dr. J. J. Reynders for his help and constructive criticism which were of invaluable assistance especially at the very beginning of work. Grateful acknowledgement is due to Dr. A. Jongerius who kindly introduced me to the different methods in soil micromorphology and gave me all possible help in order to finish this section of the study. Many thanks are due to Mr. W.L.P.J. Mouthaan for his helpful suggestions in many problems. Mrs. T. Baretta-Kuipers determined plants collected in the region and Drs. J. H. de Gunst examined some chitinous skelets of soil fauna. My thanks are due to them for helping me in these specialized subjects. I feel indebted to Dr. H. Bent and Drs. H. Klunder for the introduction in measuring techniques of X-ray fluorescence and to Mr. H. Vrins BSc for his invaluable help and constructing advice in X-ray diffraction. It is a pleasure to express my gratitude to the following for their help and suggestive criticism: Dr. R.D. Crommelin, Dr. H.J. von M. Harmse, Dr; J. van Donselaar, Drs. J. Th. de Smidt, Drs. D. Creutzberg, Drs. P. G. E. F. Augustinus and Mr. P.A. Teunissen BSc. Acknowledgement is made to a team of soil surveyors working during the period February 1965 to May 1966 at the Euphrates Project in Syria: Drs. F. Bos, Drs. A. L.T.M. Commissaris, Drs. P. Petermeyer, Drs. A.F. Sanders, Drs. J.J. Scholten, Drs. W.J. Vreeken, Drs. S. Wijnhoud, Mr. H. Van Oordt BSc, Drs. H.G.A. Van Panhuys, Drs. L.A. Van Sleen and especially to Drs. M.F.W. Zijsvelt for his interesting suggestions and Mr. J. Schoute BSc for collecting plants throughout the region. Thanks are due to Mr. L. Fürste, Mr. D. Schreiber, Mr. G. Heintzberger and Mr. D. Schoonderbeek for their practical assistance in micromorphology, to Mr. G. van Omme and Mr. F. Henzen for the skill and speed with which they have prepared the illustrations and maps, and to Mr. A. Reijmerink for the making of photopraphs. I consider it a pleasant duty to express my gratitude to Mr. P. van der Kruk for correcting the English of the manuscript. The assistance of Mrs. G.H. Visser-v.d. Geest, Mrs. M. Massaro- Ketting-Olivier, Miss H.J. van Lith, Mr. G. H. de Vries and Mr. G. Kleinveld of the Institute of Soil science (Utrecht) was greatly appreciated. A special word of thanks is also due to Mr. J.H.M. Witjes, Mr. H.C. Van Den Beemt and Mr. J. F. M. Van Tienen for undertaking typing of parts of the manuscript. I am greatly obliged to the General Organization of the Euphrates Project (Damascus), Sir Alexander Gibb & Partners (London) and the Royal Tropical Institute (Amsterdam) for their valuable help which was indispensable for the completion of this thesis. I received a grant from the Ministry of Education (The Netherlands) for the multiplication of the manuscript which I gratefully accepted. In conclusion I warmly thank the co-operators of the Euphrates Project at Raqqa especially Mr. Garo Megerdikhian, Mr. Ibrahim Knetir and Mr. Abu Bechir who were my delightful company on many desert trips and made my stay enjoyable with the best memories. CONTENTS

Page PREFACE 6

ACKNOWLEDGEMENTS

CHAPTER I ATMOSPHERIC CLIMATE AND SOIL CLIMATE 15

A. Atmospheric climate 15

1. General 15 a. A general picture 15 b. Syria 16 2. Precipitation 17 3. Temperature 19 4. Relative air humidity 20 5. Evaporation and evapotranspiration 21 6. Air pressure; wind direction and velocity; sand-dust storms 23 7. Sky cover and relative duration of sunshine 24 8. The aridity index of the Martonne and zonality of soils 25 9. Classification of arid climate 27 10. Palaeo-climate 28

B. Soil climate 30

1. Influence of aridity on soil properties 30 2. Soil moisture 31 3. Soil temperature 32 4. Surfacial supply and run-off of water 33

CHAPTER II GEOLOGY, MORPHOLOGY AND HYDROLOGY 35

A. Geology 35

1. Tectonical review 36 2. Stratigraphy and lithology 36 40 3. Geological history

B. Morphology 42

1. Euphrates terraces and flood plain 45 Page a. Flood plain 45 b. Holocene terrace or lowest terrace 45 c. Pleistocene terraces 47 2. Balikh terraces and flood plain 48 a. Flood plain 48 b. Holocene or lowest terrace 49 c. Upper Pleistocene terrace 50 3. Volcano region 50 4. Gypsum region 51 5. Limestone region 52

C. Hydrology 53

1. Hydrology of Syria 53 2. Hydrology of the Balikh Basin 54 a. Superficial water 54 b. Chemical composition and depth of groundwater 55 c. Storage and use of water by man 55

CHAPTER III MINERALOGY 57

A. Mineralogical analyses of the sand fraction (50-500n) 58

1. Analytical methods 58 ' 2. Problems in connection with the method used 58 3. Principles and methods of heavy mineral research 60 4. Description of minerals 61 a. Heavy minerals 61 b. Light minerals 62 5. Mineral provinces and associations 63 a. Heavy minerals 66 b. Light minerals 71 6. Gypsum, hemihydrate and anhydrite 73 7. Weathering of soil minerals 73 8. Conclusions 78

B. Mineralogical analyses of the clay frac tion (< 2 (j, ) 79

1. Method of analyses 79 2. Mineralogical composition of the clay fraction 81

C. Mineralogical analyses of the silt fraction 83 D. Mineralogical analyses of source rocks for the soil minerals. 85

1. Origin of the brown loam 85 2. Origin of clay in the gypsum deposits 88 3. Mineralogical composition of the Holocene basalt 88 E. Summary 89

CHAPTER IV SEDIMENTOLOGY OF THE SOIL MATERIAL 91 1. Sedimentology of the brown loam covering the plateaus 91 2. Sedimentology of the sandy gypsum deposits 93 3. Sedimentological characteristics of the other soil materials 94 4. Some observations about sedimentation during and after a sand- dust storm 94 Page CHAPTER V FLORA AND FAUNA 96

A. Flora of the Euphrates-Balikh Basin 96

1. Effect of climate on vegetation 96 2. Effect of soil and topography on vegetation 98 3. Vegetation of the different regions 99 4. The occurrence of phytoliths 102 B. Fauna of the Euphrates-Balikh Basin 104

1. Vertebrates 104 2. Soil fauna 105

CHAPTER VI LAND USE 106 1. History of land use 106 2. Farming system in the Balikh Basin 107 a. Valley lands of Euphrates and Balikh 107 b. Plateau lands 107

CHAPTER VII MAPPING METHODS 108 1. General mapping method with aerial photographs 108 2. Field classification symbols 109

CHAPTER VIII SOILS OF THE BALIKH BASIN 112 A. Description and analyses of the soil profile 112 1. Description of method of analyses 112 2. Texture analyses 113 3. Description and analyses of the soil profile 116 a. Soil horizon designations 116 b. Clay minerals as related to average values of oxides in the clay fraction 140 B. Classification of soils 140 1. Soil classification criteria 140 2. Description and classification of soils according to the 7th Approximation with supplements 141 a. Entisols of the Balikh Basin 142 a. 1. Fluvents 142 a. 1.1. Torrifluvents 142 a. 1.2. Ustifluvents 144 a. 2. Orthents 146 a. 2.1. Torriorthents 146 a. 3. Psamments 146 a. 3.1. Torripsamments 146 a. 3.2. Ustipsamments 147 b. Aridisols of the Balikh Basin 147 b.l. Orthids 147 b. 1.1. Calciorthids 148 b. 1.2. Gypsiorthids 154 b. 1.3. Camborthids 158 b. 1.4. Salorthids 161 Page 3. A comparison with other soil classification systems 161 4. The soil map 162

C. Morphology and m icromorphology of Aridisols of the Balikh Basin. 163

1. Typic Calciorthids; loam lying over Pleistocene gravel 166 a. Morphology 166 b. Micromorphology 167 c. Organization within the pedological features 168 2. Typic Calciorthids; Holocene loam of the Balikh 168 a. Morphology 168 b. Micromorphology 169 3. Typic Gypsiorthids 170 4. Typic Camborthids developed in lapilli mixed with calcareous loam 170

CHAPTER IX SOIL GENESIS IN THE BALIKH BASIN 181

A. Soil forming processes 181

1. Soil physical processes 181 2. Soil biological processes 182 3. Soil chemical processes 184 a. Relatively soluble constituents 184 1. Calcium carbonate 184 2. Gypsum 185 3. Soluble salts (more soluble in cold water than gypsum) 185 b. Relatively insoluble constituents 186 1. Silica 186 2. Sesquioxides 187 3. Clay minerals 188

B. Soil formation as related to time 189

SUMMARY 191

LITERATURE A. Alphabetically arranged according to author or editor 193

B. Alphabetically arranged according to title 196

CURRICULUM VITAE 197

APPENDICES I. Locality map of Syria

II. Geo-pedological profiles

III. Soil map of the Balikh Basin; northern part; scale 1:50.000

IV. Soil map of the Balikh Basin; southern part; scale 1:50.000 STELLINGEN

I Het verdient aanbeveling voor bodemgenetisch onderzoek een methode te ont- wikkelen om "phytolitaria" quantitatief te bepalen.

II Een micromorphologisch onderzoek is in vele gevallen noodzakelijk voor een juiste bodemclassificatie.

III Plasma concentraties zouden een rol moeten spelen in Brewer's classificatie van plasmic fabrics. Brewer. R. 1964. Fabric and mineral analysis of soils.

IV Een K-fabric zal over het algemeen eerst dan continue zijn, indien het zand- gehalte van een kalkrijke grond hoog genoeg is. Daarom wordt deze voorwaar- de, waaraan een K-horizon volgens Gile, Peterson en Grossman moet voldoen, onjuist geacht. Gile, I.H., Peterson, F.F. and Grossman, R.B. 1965. The K-horizon: a master soil horizon of carbonate accumulation. Soil Sei. Vol. 99. No 2.

Een lithologische kaart zou in bodemkundige rapporten een normale bijdrage tot de oppervlakte geologie moeten zijn. VI De definitie van "loss" behoort niet alleen afhankelijk te zijn van textuur, maar ook van origine, genese en voorkomen. Doormaak S. V. D., J.C-A. v. 1945. Onderzoekingen betreffende de lössgfonden van Zuid- Limburg. Proefschrift Wageningen.

VII De verklaring van Kuenen en Perdok betreffende het ontstaan van "desert frosting" is onvolledig. Kuenen, Ph. H. and Perdok, W.G. 1962. Experimental Abrasion 5. Frosting and defrosting of quartz grains. The J. of Geol. Vol. 70. No 6.

VIII Kristalvormen kunnen bij de voorbehandeling ten behoeve van de mineralogische analyse worden aangetast door toevoeging van 0, 2 N HC1, waardoor bepaalde diagnostische waarden verloren gaan. Dit proefschrift, hoofdstuk III.

DC De uitgestrekte gipsafzettingen in Zuid-West Azië zijn afkomstig van het Mio- ceen, hebben dientengevolge de Pluviale perioden meegemaakt, en zijn daarom als relatief stabiel te beschouwen.

X In een bepaalde geologische periode bestaat er een relatie tussen de sedimen- taire opbouw van een geosynclinaal en de bodemvorming op een aangrenzend continent. Erhart, H. 1956. La genèse des sols en tant que phénomène géologique. Esquisse d'une théorie géologique et géochimique. Biostasie et Rhexistasie.

XI Verkeersaanduidingen in verband met werkzaamheden naast de rijbaan dienen verwijderd te worden als er geen arbeid verricht wordt.

M. A. Mulders Utrecht, 31 maart 1969 ERRATA

THE ARID SOILS OF THE BALIKH BASIN (SYRIA). M. A. MULDERS, 1969.

Acknowledgements, page 8, line 1 from bottom: read: Dr. instead of: Dr; page 28, line 18 from top: read: at instead of: a page 47, legend fig. 9: . read: Lowest or Holocene instead of: Lowest Holocene page 61, line 32 from bottom: read: occurred instead of: occured page 48, line 19 from top: read: occurrence instead of: occurence page 53, line 14 from top: read: with instead of: withe page 53, line 21 from top: read: southward instead of: soutward page 58, line 4 from bottom: read: in instead of: on page 77, line 8 from top: read: occurrences instead of: occurences page 77, below Table 19: add: legend + = Ca; " = Na and/or K page 90, line 1 from top: read: Table 25 instead of: Table 25a page 101, line 4 from bottom: read: occurring instead of: occuring CHAPTER I

ATMOSPHERIC CLIMATE AND SOIL CLIMATE

A. ATMOSPHERIC CLIMATE

1. GENERAL a. A general picture

Climate is one of the more important factors that govern vegetation structure, land use and soil type. Syria with a latitude 32, 3° - 37, 6° and a longitude 35, 3° - 41, 8° in the northern hemisphere lies in the subtropical high-pressure belt with a pronounced aridity. The cause of the subtropical high-pressure belt becomes clear on a world scale in the 3-cell meridional overturning circulation model (Hare 1961). In the tropics one finds an aequator-ward flow at low levels of the trade wind; there is an uplift of air at the intertropical front zone, a poleward flow at some higher level and subsidence near latitude 30 . In mid latitudes there is a poleward flow at low levels, an aequatorward flow above and also subsidence near latitude 30°. The subsidence near this latitude results in dynamical warming, which lowers the relative humidity and disperses cloud. Because of a cellular structure of the subtropical high pressure belt, there are gaps in the arid zone with abundant rainfall. 15 b. Syria

A narrow strip of low plains and plateaus along the coast of Syria belongs climatically to the Mediterranean Basin with warm nearly rainless summers, humid winters and relatively high air humidity. Inland Syria is a plateau land with elevations varying from 300 to 1000 m with dry hot summers and relatively cold winters with rainfall. The rainfall decreases to the centre of the area of over 500 mm to 100 mm. The interior does not profit from the Mediterranean climate owing to the presence of the Libanon and Anti-Libanon ranges parallel to the coast. The moist air masses reach their condensation level upon orographie uplift on the windward side of these mountain ranges and lose an important part of their moisture by precipitation. When the air moves downslope the absolute vapour pressure is quite low while the relative humidity is further decreased by the adiabatic warming during subsidence.

Fig. 1. Isohyetal map of Syria. - Decrease in rainfall from 1000 mm along the coast to 400 mm at Aleppo and 100 mm at Palmyra.

16 This results in a decrease in rainfall from 1000 mm along the coast to 400 mm at Aleppo and Homs. To draw direct conclusions about average yearly precipitation from the following climatic figures shown in the tables would be erroneous. The 9-17 years of recording can be just as well a dry or moist spell. But at least these data show what can be expected.

2. PRECIPITATION

To the centre of the Syrian area the precipitation decreases. The area north-west of Palmyra is less arid having a precipitation of 200-300 mm because of the presence of the Amans corridor, a valley perpendicular to the Li- banon and Anti-Libanon ranges, giving passage to moist air masses.

Table 1. Average monthly precipitation in mm from Aleppo to Deir ez Zor and from Raqqa to Tal Abyad. Month Aleppo Abu Ma'dan Deir ez Raqqa Hazimah Tal Hurayrah Jadid Zor Abyad January 65.9 35.4 33.2 34.2 40.7 41.9 57.8 February 55.1 22.4 27.4 30.1 24.7 23.2 37.1 March 41.9 23.8 19.5 24.3 26.7 34.2 31.9 April 36.7 18.8 20.7 24.2 26.3 22.4 33.9 May 12.9 8.2 6.0 7.8 11.1 7.2 23.3 June 2.7 0.1 1.2 0.8 5.7 0.7 2.5 July 0.2 0.0 0.0 0.0 0.0 0.0 0.0 August 0.9 0.0 0.0 0.0 0.0 0.0 0.0 September 1.6 2.0 0.3 0.5 2.8 1.4 1.9 October 12.5 3.7 5.7 4.9 5.0 4.0 13.0 November 24.9 12.0 20.5 11.7 15.1 9.7 25.2 December 67.6 20.7 22.9 28.1 24.5 25.0 48.7

Total 323 147 157 167 183 170 275 Years of record 17 9 9 16 10 10 10

There is an abrupt change in rainfall from Aleppo with a yearly rainfall of 323 mm to Abu Hurayrah with 147 mm. This change of humidity is clearly noticeable in vegetation, and in the colour of the soils, being dark red brown near Aleppo and light yellowish brown to pale brown in the desert. The average monthly precipitation at Raqqa deviates only slightly from that at Deir ez Zor; near Aleppo the rainfall is about twice the rainfall at Deir ez Zor.

17 From Raqqa to the North, that is to Hazimah and Tal Abyad, there is an increase in rainfall from 183 mm at Raqqa and 170 mm at Hazimah to 275 mm at Tal Abyad. During my fieldwork '65-'66, I had the impression that from Raqqa northward to Chunayz there was no change in aridity, locally conditions seemed even more arid (Hazimah). From Chunayz to Ain Isa there was a slight increase in rainfall, noticeable in the valleys, being green during a great part of the year. Sometimes heavy night dew occured north of Chunayz. North of Ain Isa rainfall increases rather abruptly, giving rise to a more green and a little bit higher grass cover, as compared with the southern area. At all the stations in table 1 the months of June, July, August and September are practically rainless.

Table 2. Precipitation at Raqqa.

Average monthly Average Maximum fall Monthly precipitation number in 24 hours precipitation in min. of wet days in mm. in mm. 1964 1965 1966 January 40.7 9.2 37.8 1967 February 24.7 7.8 39.3 1965 1966 March 26.7 7.6 20.8 July April 26.3 7.4 37.2 0.0 0.0 0.0 August 0.0 May 11.1 2.8 34.0 0.0 0.0 September June 5.7 0.5 4.0 0.0 0.0 27.7 October July 0.0 0.0 0.0 0.0 17.7 11.5 November 17.3 3.2 19.4 August 0.0 0.0 0.0 December September 2.8 0.5 27.7 42.6 10.1 29.3 October 5.0 2.7 37.0 November 15.1 4.3 22.0 January 64.8 16.4 21.0 February December 24.5 7.8 26.6 32.5 14.5 78.3 March 29.8 12.9 53.3 April Total 183 39.3 20.1 12.6 May Years of Record 10 10 10 0.2 16.5 73.5 June 0.7 0.0 0.0

Total 227 111 327

At Raqqa: January is the wettest month of the year with a precipitation of 40,7 mm. It is possible that nearly all the rainfall of the month falls in 24 hours '. The main part of the precipitation comes from cloud bursts. A precipitation of 74 mm/day occurred once in January at Deir ez Zor. Raqqa has an average of 50,6 wet days/year. Snow does not occur but hail has been observed. Vernal rain and melting of snow in the upper course of the Euphrates cause the river to have its highest level at Raqqa in April. The most striking feature of rainfall in the Syrian desert is its aperiodic

18 nature as is clearly shown by precipitation figures of the years 1964 - 1967 in table 2. The year 1965 - 1966 was a dry spell while the preceding and succeeding years were wetter than normal.

3. TEMPERATURE

The climate at Raqqa is characterized by a dry hot summer and a cool relatively humid winter.

Table 3. Temperature at Raqqa. TEMPERATURE AT RAQQA IN °C Average Average Average Range of Range of Month monthly monthly monthly monthly absolute monthly absolute temperature maximum minimum maximum minimum January 6.6 12.0 1.8 12.2 to 18.7 -7. 6 to 0. 6 February 8.7 14.7 3.4 17.2 to 23.6 -8.2 to 1.7 March 12.7 19.3 6.3 24.5 to 31.3 -3.2 to 1.5 April 17.5 24.8 10.8 29.2 to 35.8 -0.4 to 7.6 May 23.3 31.4 15.1 32. 7 to 40. 7 7.8 to 12.3 June 28.1 36.5 19.2 40.5 to 43.8 12.3 to 15.5 July 30.0 39.1 21.3 41.2 to 46.5 13.5 to 20.4 August 29.7 38.8 21.0 41.0 to 45.0 14.3 to 19.9 September 25.2 34.2 16.7 36.5 to 41.3 8.6 to 14.2 October 19.7 28.6 11.6 31.5 to 37.5 0. 6 to 9. 6 November 13.4 21.1 6.6 24. 7 to 30. 0 -7. 8 to 3. 5 December 8.5 14.4 3.6 16.2 to 23.0 -6.0 to 1.0 Years of record 10 10 10 10 10

January is the coldest month with an average monthly temperature of o o 6,6 C and an average minimum of 1, 8 C; July is the warmest month with an average monthly temperature of 30, 0 C and an average maximum of 39,1 C. The absolute maximum is 46, 5 C in July and the absolute minimum is - 8, 2°c in February. The hot season starts in May and ends in September. The maximum average daily amplitude per month mounts 17,8 C in July and August ; the minimum average daily amplitude per month is 10,2°C in January. Frost may occur from November until the end of March; temperature increases rather quickly after March, making the sowing time rather limited.

19 30 20 »Î 40 0 T Fig 2. Climatogram of Raqqa. P=precipitation t T=temperature I '0 M=months of the year. 0 JFMAMJJASOND "*— M—•

A minimum of precipitation during June-September coincides with a maximum of temperature during that time.

4. RELATIVE AIR HUMIDITY

The relative humidity is the ratio between measured vapour pressure and the maximum vapour pressure possible with given temperature.

Table 4. Percentage of relative humidity and monthly temperature at Raqqa.

Month Average monthly Percentage temperature relative humidity

January 6.6 79 February 8.7 71 March 12.7 59 April 17.5 54 May 23.3 40 June 28.1 33 July 30.0 38 August 29.7 39 September 25.2 42 October 19.7 47 November 13.4 62 December 8.5 75

Years of Record 13 8

From the definition above it will be clear that it is necessary to compare the percentages of the relative humidity with the average monthly temperature, in order to get an idea of the total amount of air humidity. The relative humidity is on its maximum in January with 79%, and on its minimum in June with 33%, July and August with 38% and 39%. It increases rapidly from October with 47% to November with 62%; there is a decrease from February with 71% to May with 40% . The atmospheric 20 vapour has a function comparable with the function of the glass of a hothouse; solar radiation can enter a hothouse, but practically no heat radiation can leave. With a low air humidity as in deserts and mountain regions, there is very hot sunshine, cold shadow and great differences between day and night temperatures. This phenomenon is clearly marked at Raqqa: January has a relatively high air humidity and a relatively low average daily amplitude of temperature, In the period June-July-August there is a low air humidity, a high maximum temperature and a high average daily amplitude.

5. EVAPORATION AND EVAPOTRANSPIRATION

Table 5. Free water surface evaporation at Raqqa.

Free water surface evaporation in mm. Month Average daily Average monthly % age of total

January 1.4 43 1.7 February 2.2 62 2.5 March •4.3 133 . 5.4 April 6.3 189 7.6 May 8.6 267 10.8 June • 13.2 396 16.0 July 14.3 443 17.9 August 12.2 378 15.3 September 8.4 252 10.2 October 5.3 164 6.6 November 3.0 90 3.6 December 1.9 59 2.4

Total 2 476 100 Years of record 8

Raqqa with a yearly free water surface evaporation of 2476 mm, being 14 times the evapotranspiration, (table 7) has in winter a relatively low and in summer a very high evaporation .

21 Table 6. Yearly free water surface evaporation from Erzurum to Bagdad.

Place yearly free water surface evaporation in mm.

Erzurum 960 Urfa 2248 Raqqa 2520 Abu Kemal 2750 2934

note: Urfa is located in Turkey at the upper course of the Balikh.

Evaporation increases downstream of the Euphrates. It is only twice the precipitation in Erzurum, the upper course of the Euphrates in Turkey. In the other places it is about 6 to 20 times the precipitation.

To obtain correct data of evaporation is still a great problem. Therefore, the more complicated phenomenon of the potential evapotranspiration by a vegetation cover is calculated from a formula. The formula of Papadakis (1957) was used to calculate the evatranspira- tion:E+=l,5(eme-ed) where E is the monthly evapotranspiration in cm, e the saturation vapour pressure corresponding to the average temperature of the month and e the saturation vapour pressure corresponding to dew point. Usually e^ is equal to the saturation vapour pressure corresponding to the average daily / nii. minimum temperature (e ) • In this formula, the influence of temperature in increasing saturation vapour pressure has been taken as a measure of its influence on evapotranspiration; summer figures are sufficiently high in this method, this being the failure of other methods.

Data of evapotranspi ration of Damascus, Aleppo and Deir ez Zor, calculated by Papadakis in his Climatic tables for the world (1961), are respectively 168, 160 and 199 cm/year. Only in January at Raqqa, is rainfall greater than evapotranspiration, the difference or leaching rainfall being 2 cm (table 7). The dry season, according to Papadakis during months in which rainfall, plus the water stored in soil from previous rains cover less than half of the evapotranspiration, extends for Raqqa fx*om April until November.

22 Table 7. Evapotranspiration in cm at Raqqa; E = 1, 5 (e -e )

Month Evapotranspiration January 2 February 4 March 5 April 10 May 19 June 28 July 30 August 30 September 21 October 15 November 7 December 3

Total 174

Penman has made use of evaporation data in calculating the potential

evapotranspiration. Formula of Penman: E = C.EQ; EQ is the evaporation of a free water surface and c is a correction factor depending on the nature of the crops and on the degree inwhichthe soil is covered by them. For grasslands c = 0,65 and the yearly potential evapotranspiration at Raqqa is 1609,4 mm. A yearly rainfall of 183 mm, derived from winter and early spring rains, can support the natural grass vegetation only for a short period.

6. AIR PRESSURE; WIND DIRECTION AND VELOCITY; SAND-DUST STORMS

Rain-bringing depressions move in easterly direction during winter losing a great part of their moisture on the Libanon and Anti-Libanon ranges, and giving some rain in Syria. Western direction of the winds is much less pronounced in winter than in summer, eastern winds can occur also.

The differences in air pressure are greater in summer than in winter, as a consequence the wind velocities are higher and there are more sand-dust storms in summer. The wind velocities are high enough to give rise to a great number of sand-dust storms (table 8) . The maximum wind velocity measured at Raqqa is 20m/s'ec.

23 Table 8. Wind velocity and sand-dust storms at Raqqa.

Month Monthly average Average monthly number of days wind velocity with sand-dust in m/sec. storms

January 0.7 2.8 February 1.1 2.9 March 2.1 3.4 April 1.9 3.3 May 2.4 3.7 June 2.8 4.9 July 2.9 6.0 August 0.7 4.8 September 1.1 3.6 October 1.2 2.2 November 1.2 2.0 December 0.4 2.4 Years of record 9 7

When the wind velocity increases in March, also the number of sand-dust storms is increasing. There may be a relation to the start of agricultural activities at that time which results in a destruction of the soil surface.

The duration of these sand-dust storms is 4-10 hours up to a maximum of 1-2 days. Generally the visibility is less than 1000m. Locally in the centre of the storm this can be less than 25m, as happened to me near Hazimah.

In summer whirl winds occur daily; their diameter varies from a few meters up to more than 100 meters. These whirl winds arise from the local differences in the degree of heat absorption and heat radiation of the soil surface; the ascending hot air takes some soil particles with it in a spiral-like upward movement. As energy is depleted at a certain height the dust and sand disperse and sink after some time. However, even with calm weather, some of it stays in the air.

7. SKY COVER AND RELATIVE DURATION OF SUNSHINE

The degree of sky cover is practically zero in summer, as a consequence there is a maximum of sunshine. The degree of sky cover is increasing towards the winter to about 50%

24 (4 octas). There is relatively much sunshine in winter due to the fact that cloud- iness occurs especially in the night.

Table 9. Duration of sunshine at Raqqa.

Month Average Average total hours percentage of actual of sunshine sunshine at Raqqa at Raqqa January 157.8 54 February 172.9 60 March 237.4 68 April 257.8 70 May 322.7 81 June 361.0 92 July 382.6 96 August 366.1 93 September 332.7 92 October 276.2 85 November 214.4 74 December 158.0 55 Total 3 240 Years of Record 9 9

8. THE ARIDITY INDEX OF THE MARTONNE AND ZONALITY OF SOILS.

Rainfall/temperature indices are intended to summarize features of the macro-climate. They are gross values which do not entirely reflect micro- climate and run-off processes. However, general processes of soil formation can be deduced. The Martonne suggested the following index of aridity: P/10+T, where P represents the annual precipitation in mms and T the annual temperature in °C. This index can be used in summarizing the climatical, hydrological and soil formative conditions. A correlation between the index of the Martonne and the soil type will be possible in the Near East since climate has not changed very much after the end of the Pleistocene. The curves of equivalence of aridity index and the main soil types of Syria are shown in fig. 3.

25 300km

Fig 3. Aridity index of the Martonne (adapted from Abd-al-Al) and zonality of Syrian soils (adapted from W.J. van Liere).

legend of soils: a. Red Mediterranean soil. b. Grumusol. c. Arid brown soil (Cinnamonic ace. van Liere) d. Gypsiferous soil. e. Grey desert soil.

Main soil types of Syria: a. Red Mediterranean soils: Dominant colour red; clay loam and loam; mont- morillonitic; pH 7-8; little horizonation; some clay movement. b. Grumusol: Dominant colour dark red, brown, dark brown and black; mont- moriilonitic ; pH 8-8,5; no horizonation; self-mulching. c. Arid brown soil: Dominant colour reddish yellowish brown; illite, palygorskite and montmorillonite ; loam and clay loam; highly calcareous; pH 8-9; little horizonation; calcic horizon; unstable structure. d. Gypsiferous soils: Dominant colour yellowish-orange brown to white powdery; pH 8,5; often gypsum crusts.

26 e. Grey desert soils: Dominant colour brown-grey and grey; highly calcareous loam.

The curves of equivalence of aridity index roughly coincide with the major soil types. The 25 index curve corresponds to the boundary between Red Medi- terranean soil and Grumusol. The boundary between Grumusol and Arid brown soil is approximately the 10-13 index curve. Arid brown soils are found from the 10-13 index curve up to approximately the 5 index curve. The 5 index curve delimits a zone with soils without any profile development. There are three main zonal types : humid red soils, arid to semiarid brown soils, and arid grey soils in areas with a precipitation being less than 100 mm. The content of iron-oxides is decreasing with increasing aridity. The gypsiferous soils do not correspond to zones with equivalence of aridity index, the climatic habitus being overshadowed by soil characteristics inher- ent from the gypsiferous parent material.

9. CLASSIFICATION OF ARIP CLIMATE

There is no generally accepted definition for aridity, but one of the simplest classifications states that 250 mm rainfall is the dividing line between arid and semiarid, and 500 mm between semiarid and humid. These limits of rainfall are suitable for the Mediterranean area, however, for tropical margins of the deserts a greater amount of rainfall is required to make an area humid. After Dixey (1962) arid regions can be divided into: - semiarid 250-300 mm to 500 mm precipitation - arid 50 to 300 mm precipitation - extremely arid less than 50 mm precipitation

In the semiarid regions water is deficient for normal crop growth,but they have a great significance as natural grass-lands. As for the Balikh Basin: Raqqa and Hazimah have an arid climate ; Tal Abyad on the Turkish border with a precipitation of 278 mm has an arid to semi-arid climate. After Bagnouls and Gausseii (1957) a month is dry if precipitation in mm 27 is less than twice the temperature in °C. This means at Raqqa that April until November is the dry period. Raqqa has to be classified according to theseauthorsas a Xerothermo-mediterranean climate, having eight dry months a year.

However, distribution and amount of rainfall together with maximum and minimum temperatures are of great significance to the distribution of crops and vegetation. Using humidity regime and temperature regime Papadakis (1961) classified Deir ez Zor and Damascus as a frosty hot subtropical desert with the addition more grassy than usual in desert; Raqqa belongs to the same class. A desert more grassy than usual due to the mediterranean influence in winter, while the summer has a continental influence. When using vegetational criteria only, the degree of vegetation cover, the possibility of dry farming and grazing result in a classification as semi-desert.

10. PALAEO-CLIMATE

Hull and Blanckenhorn discovered that Pleistocene pluvial periods a lower latitudes were directly related to the Pleistocene glacial periods in middle and higher latitudes (Butzer 1961), During the greater part of the Pleistocene the climate at lower latitudes, in North-Africa and the Levant, was as arid as it is today, the pluvials were only temporary features.

After K.W. Butzer: full aridity set in at least 8000 years before the end of the last glaciation. Valley systems are evidence of an intensive erosion and greater humidity during the Pleistocene, Their incision took place during the Middle and Upper Pleistocene uplift. Terra Rossa formation took place during the Riss-Würm interglacial period in the Libanon ranges and in Turkey. The greater part of the Holocene was arid or even more arid than today. In the Atlantic period there was a markedly greater humidity and rainfall, making possible a more exuberant fauna and flora. There was a greater aridity during Preboreal and Subboreal; the early historical desiccation shortly before 2000 B.C. was quite severe, as conditions were extremely arid. The reversal from an extremely arid climate in Sub- boreal time to the arid climate of today took place about midway of the last

28 Table 10. Pleistocene and Holocene climate of the arid zone at lower latitudes (North-Africa and the Levantine Area) (adapted from K.W. Butzer 1961.).

Geological time Climate

Pleistocene Lower Pleistocene Pluvial (GUnz glacial) 600. 000 years B.C. Interpluvial (Günz-Mindel interglacial) Middle Pleistocene Pluvial (Mindel glacial) 475.000 years B.C. Major Interpluvial (Mindel-Riss interglacial) Pluvial (Riss glacial) Interpluvial (Early Riss-WUrm interglacial) Upper Pleistocene Pluvial (Late Riss-WUrm interglacial) 100. 000 years B.C. Pluvial (Early Wurm glacial) Postpluvial (Late WUrm glacial) Holocene Preboreal Extremely arid 8500-6800 B.C. Boreal Arid 6800-5600 B.C. Atlantic Moist, warmer 5600-2500 B.C. Subboreal Extremely arid 2500-8/500 B.C. Subatlantic Arid, slightly moister After 500 B.C.

millenium B.C. Only short term fluctuations occurred since that time,never ex- ceeding the order of a few hundred years. Roman ruins near Raqqa e.g. Al Rasafah, Halabia and Zalabia, gave the impression that climatic conditions in Roman time did not differ much from today; this applies also to Palmyra and Dura Eropos. The abandonment of wide areas of the Levant during the sixth century A.D. was not due to a greater aridity, but was a result of increasing economic dete- rioriation and political instability in the disintegrating Roman empire. In the Subatlantic arid climate short term fluctuations occurred with more or less markedly dry and moist spells. These climatic fluctuations, giving only a small fluctuation of temperature and rainfall, had not much influence on soil development. The period since 1900 A.D. can be seen as a dry spell. To long term droughts of a few centuries man can adapt himself without special hardship. However, short term droughts of a few years duration can bring swift disaster to agricultural communities. Droughts of economic importance plagued the Levantine area in the 1920s 29 and 1930 s. The great variation in rainfall means a special problem for dry farming and stock raising, as did the low rainfall during the winter of 1966. Therefore, it is necessary to maintain a balanced view of minor climatic fluctuations of a few years duration. A moist period during the Atlanticum explains soil characteristics associated with wetting at greater depth in soils on the plateaus as are mottling and gypsic horizons. The soil profile will have been wetted more deeply in the At- lanticum while a thoroughly wetting in recent times on the plateau lands is restricted to the topsoil and subsoil.

B. SOIL CLIMATE.

The soil climate is characterized by a "non flushing regime" (Rode 1961), that has: a. A groundwater table which lies too deep under the surface to have influence on soil forming processes. b. Supply of water by rainfall and to a lesser degree by night dew. c. Drain of water by evaporation and transpiration. High evaporation results in an upward movement of soil water. These processes determine the properties of the soil profile. The results of climatic action on soil will be discussed below.

1. INFLUENCE OF ARIDITY ON SOIL PROPERTIES

The effective rainfall is about half of the total rainfall, the other half falling in too small quantities and/or evaporating from the leaves or directly from the soil surface. In winter there is a slight chemical weathering due to the presence of soil moisture. Chemical weathering is on its maximum in the early spring owing to a maximum of soil moisture, higher temperatures and as a consequence relatively high biological activity. In summer all weathering by the solvent action of water ceases as a result of the scarcity of water. The intense insolation during summer destroys most of the organic matter formed in winter in the upper soil layer. The slight chemical weathering results in corrosion of sodium and/or calcium containing minerals. Calcium carbonate is precipitateu in subsoil and deeper subsoil but sodium moves with the upward moving soil water to the surface and can lead to accumulation after the evaporation of water. 30 If chloride ions are abundant also calcium and magnesium can become accumulated in the topsoil. These salts being hygroscopic can attract water from night dew and appear as dark coloured patches on the soil surface in the morning, the so called sabakh phenomena. Because leaching is nil calcium and/or sodium are the dominant cations and the pH is alkaline.

2. SOIL MOISTURE

The percentage of moisture in loamy soil in relation to soil depth is shown in fig. 4. In dry brown loam the percentage of moisture in the deeper subsoil at 1 m is about 10% and there is an increase to about 15% below this depth. Irrigated loamy soil has a moisture content at 2 m of about 20% even if irrigation has not been practiced for years. However, the upper 100 cm of such soil is below wilting point and cannot support plantgrowth (wilting point for loamy soils will be about 15-18% for most plants). In addition the upper 40 cm are extremely dry.

depth in cm

200

300 0 10 20 % moisture—•

Fig. 4. Percentage of moisture in relation to soil depth as determined during August 1965. legend: T=non-irrigated brown loam; Raqqa terrace; land use cereals. B= since 2 years non-irrigated clay loam-, Balikh; land use cereals. 1= irrigated brown loam; Hamret terrace (profile 17); land use cotton; 1= 4 days after irrigation ; 2= 11 days after irrigation.

31 The curves 1 and 2 of fig. 4 give an idea about water consumption by plants and evaporation from the soil surface. The intervals of irrigation gifts on this field were estimated to be 16 days. Cracks are formed upon drying after irrigation to a depth of 10-17 cm. These large interconnected cracks form an irregular pattern in which other systems of smaller and shallower cracks develop. The soils are generally far below field capacity, which is 25-30% moisture for brown terrace loam, below the zone of wetting at about 2 - 3 m non- irrigated soils are dry. The groundwater table is generally found on the plateau lands at a depth of 20-30 m.

3. SOIL TEMPERATURE

There is very little reflection or absorption of short wave radiation of the sun by clouds in summer due to a low degree of sky cover. Some reduction occurs by dust in the air during and after dust storms. However, the depletion is low and the result is a high amount of solar radiation. This will heat the air and the soil owing to the absence of sufficient water in the topsoil.

0 Table 11. Monthly soil temperature at Raqqa in C.

Month Average monthly temperature Range of extreme temperatures of the soil at a depth of of the soil at a depth of 10 cm. 10 cm. 20 cm. 50 cm. 100 cm. Maximum Minimum January 8.0 8.8 10.9 14.6 8.4 to 14. 8 -0.6 to 8.9 February 10.3 10.8 11.8 13.9 11.7 to 17.5 2.0 to 11.6 March 14.2 14.5 15.3 15.6 17.6 to 23.4 1.8 to 13.8 April 20.4 20.5 20.2 19.1 21.3 to 30.4 10.4 to 19.0 May 27.5 27.3 26.2 23.7 30.3 to 39.1 16.7 to 24.9 June 33.7 33.3 32.1 29.0 37.5 to 42. 0 22. 8 to 32. 0 July 35.6 35.4 34.4 31.3 39.4 to 41.6 25.3 to 34.6 August 35.4 35.4 34.7 32.4 29.9 to 41. 2 24. 5 to 34. 5 September 30.2 31.1 31.5 30.9 33.2 to 37. 8 19. 9 to 29. 9 October 23.0 24.0 25.9 27.4 24.4 to 31.9 8. 6 to 20. 8 November 16.0 17.2 19.7 22.9 15.9 to 26. 4 3.3 to 15.4 December 10.6 11.4 14.0 18.0 12.0 to 16.9 2.3 to 10.3 Years of Record 7

32 The average monthly soil temperature in the topsoil fluctuates at Raqqa between 8 C in January and 35,6 C in July. Extreme minimum and maximum temperatures measured are respectively - 0,6 and 42°C. The yearly amplitude is decreasing downwards in the soil profile. At 200 cm depth soil temperature is about 27°C in August. Generally temperature is increasing at a depth of 5 cm from 10 o'clock to 13 o'clock only about 3-4°C, at a depth of 50 cm 0, 5°C and at 100 cm there is no increase. Differences between day and night temperatures are larger. Prolonged selection of drought tolerant plant species in the hot arid climate resulted in a sparse vegetation whose capacity to resist water loss is well marked. A high albedo or reflection intensity is an ecologically desirable thing in reducing the evaporation of water and fluctuation of soil temperature. The vegetation is light in colour and appears pale grey to light brownish in the full sun, resulting in a high albedo. The albedo is related to the soil type. It is low in the dark coloured volcanic deposits and irrigated soils, and high in the light-coloured gypsum deposits and soils with salt efflorescences. In the terrace loams it is increased by a lighter coloured platy surface layer and the occurrence of white fungi. Water is a better conductor of heat than air, more of the heat will be used to heat deeper soil layers and in evaporation (80 - 90%), less will be used in heating the air. Therefore, soil temperature of irrigated soils will be lower than that of non-irrigated soils and the difference in temperature between topsoil and deeper subsoil will be smaller. Maximum temperatures of 42°C will not be reached in irrigated soil (such temperatures would be unfavourable for the meta- bolism of cottonroots).

4. SURFACIAL SUPPLY AND RUN-OFF OF WATER

During the winter occasional violent rain storms of a cloud burst type loosen the surface soil and transport it down the slopes into the wadis. The surface has become somewhat resistent against such erosion by the formation of a platy surface layer. The surfacial supply of water is dependent on the permeability of the surface soil layer. 33 The intake rate of the topsoil (table 12) has been measured with the aid of steel cylinders wii'i diameter 25 cm and height 35 cm. The cylinders were driven 15 cm into the soil surface. Water was made to penetrate around the cylinder to prevent lateral drain of water at the foot of the cylinder by soil suction. Measurement of intake rate should be done with a constant head. In the case of loamy soils, this was obtained in practice: by refilling the cylinder every hour.

Table 12. Average intake rate in cm/h of the topsoil.

Region texture intake cm/h

Volcano lapilli loam 5 Ham ret loam 6 Balikh clay loam 2 Euphrates loamy sand 9,5 silty loam 6 clay loam 0,9

Intake rate depends on texture, water content, chemical composition of the saturation extract and the packing of soil aggregates. Lapilli loam has a lower intake rate due to a higher sodium content resulting in dispersion of clay upon wetting and consequent obstructing of the voids. Run-off will be low in the Terrace loam soils, but will be more significant in the clay loams of Balikh and Euphrates, these having a low intake rate.

34 CHAPTER II

GEOLOGY, MORPHOLOGY AND HYDROLOGY

A. Geology:

Geology of Syria is discussed by Blanckenhorn (1915). A review is given below. Conditions in the Syrian and Arabian area were terrestrial during the Palaeozoicum and the first half of the Mesozoicum. The area was linked with the Sahara until the Upper-Tertiair y when the rift valley of the Red Sea formed. The Syrian area is bounded to the north by the folded area of the Tauros and Kurdistan mountains. The morphological character of the Syrian-Arabian area as well as the Sahara is determined by faults. Where lava was present at greater depths it has been extruded along the fault lines; also efflata have been formed.

Syria can be divided in five stratigraphie al units: 1. The Libanon ranges along the coast built up of Jurassic and Cretaceous limestones . 2. The Anti-Libanon and Palmyra mountains built up of Cretaceous limestones. 3. South-east Syria with Mesozoic sediments. 4. The Tertiairy of inland Syria with Miocene lagoonal sediments in the Jazirah, surrounded by Palaeogene sediments. 5. Basalt flows south of Damascus, where they cover a vaste area, and in the vicinity of Horns, Aleppo and Raqqa having a limited extension. 35 The area under consideration is located in the Tertiairy of inland Syria.

1. TECTONICAL REVIEW

The Balikh area is located in the marginal part of the Arabian platform which is mobile and belongs to the African platform. The stable part of the Arabian platform has a shallow Precambrian basement and gently dipping sedimentary cover. The mobile part is characterized by linear and block type fold- ing in the sedimentary cover and the basement is varying in age and depth. Some tectonical structures of the area are given in fig. 5. Their influence on morphology is discussed in section B.

The Balikh Basin has been lifted up in the north while descending tectonical movements have prevailed in the south. Therefore, the region can be divided in two tectonical units as described below. The Tuwal al Aba anticlinal uplift extends from east to west and is composed of Lower to Middle Miocene strata. To the west it is bordered by a fault. The Miocene Euphrates depression extends south of this uplift. The platform cover is built up of Miocene strata. Neogene-Quarternary depressions have developed in this depression and are in filled with Pliocene and Quarternary strata. These depressions are separated by faults.

2. STRATIGRAPHY AND LITHOLOGY

Apart from a limited area with basalt, the Balikh Basin is underlain by a bedded sequence of Neogene sedimentary rocks and alluvial, proluvial or aeolic Quarternary deposits. The Miocene is presented by lagoonal sediments which belong mainly to the Fars series. Litho logically these series may be divided into the Lower and Upper Fars, the former outcropping in the region more extensively. The lower Fars rocks are an interbedded sequence of marls, gypsum, clays, silty sandstones and limestones. Marl and gypsum are the predominant rock types. The dominant rock type of the Upper Fars is sandstone with interbedded siltstone. The Pliocene rocks are of the terrestrial type, being lacustrine, alluvial or proluvial. The Pliocene rests with a sharp unconformity on the underlying 36 /o

Fig.5. Tectonic map of the Balikh Basin ( adapted from Technoexport 1963 ) . Legend : 1 = Jarablus anticlinal uplift; 2 = Tuwal al Aba anticlinal uplift; 3 = Area with northwestern trend of folds; 4 = Slope of the nortwestem Syrian uplift; 5 = Euphrates Miocene depression; 6 = Turkmaniyah Oligocène-Quarternary trough; 7 = Basalt; 8 = Anticline; 9 = Syncline; 10 = Anticline supposed according tot gravimetric data; 11 = Fault expressed in landscape; 12 = Contours of the Pliocene depressions. lagoonal Miocene sediments. The dominant rock types are conglomerates, sandstones, clay, marls and limestones. The Pleistocene has been divided into the Lower, Middle and Upper Pleis- tocene. The different pluvial and interpluvial periods of these are shown in table 10. The Lower Pleistocene is represented by alluvial pebbles and proluvial gypsum-bearing deposits. The alluvium comprises the alluvial cover of the IV- th Euphrates terrace (thickness 10 - 15 m) built up of gravel, and the old proluvial conglomerates and carbonate crust lying directly on an older Quarternary

37 Fig. 6. Geological Map of the Balikh Basin ( adapted from Technoexport Report 1963 ). Legend : al Q Quarternary alluvial: pebbles, conglomerates, sands, sandy loams, loams. b Q Upper Pleistocene-Holocene basalts. P Pliocene : sands, sandstones, pebbles, conglomerates, marls. M Lower-Middle Miocene : gypsum, limestones, marls, sandstones. denudation surface (thickness respectively 6m and 2m). Proluvial gypsum-bearing deposits accumulated as a result from local slight uplifting in the Tuwal al Aba swell. The Middle Pleistocene comprises the m Euphrates terrace (thickness 10 - 20m) represented by coarse gravel and poorly cemented conglomerates. The pebbles belong lithologically to the Turkish Complex with pebbles of

38 granitoid, shale, quartzite. quartz (1/3 of total), basic effusives, limestones and siliceous rocks. The Upper Pleistocene is represented by alluvial deposits and volcanic effusiva. Thealluvium comprises the II Euphrates terrace, preserved on the left side of the Euphrates valley slope and in the Balikh mouth (thickness 12-20 m). The pebbles belong lithologie ally to the Turkish complex. The II Balikh terrace belongs also to the Upper Pleistocene. It is exposed in the north of the region and comprises gravel and oblique laminated breccious limestone material mixed with loam (thickness 3 - 7m). The Upper Pleistocene volcanism is represented by the Mankhar volcanoes east of Raqqa. The Mankhar Gharbi volcano is situated in the area. The volcano is of the Somma-Vesuvius type with two sequential stages of eruption, separated by a long quiet period. The first stage has an explosion nature and no lava formed. The somma formed as an eruption ash pile, entirely made of thin laminated fine pyroclastic products, which consist of grey volcanic sand, ash, lapilli and bombs with a diameter of 10-30 cm. In the second stage the Vesuvius piles were formed inside the crater, and lava flows were acting. The piles are built up of lapilli with lava intrusions. Locally aeolic loam has been mixed with the lapilli. The geological age of the Mankhar volcanoes is defined by their piercing the gravel layers of the II Euphrates terrace. The pyroclastic material resulting from explosive igneous activity of the first stage covers the surface of the m and nn Euphrates terrace while it is lacking on the Is terrace. Hence the somma arose after the formation of the Un terrace. The lava flows cover the fine pyroclastic products. The Vesuvius piles and related lava flows of the second stage correspond in age to the Holocene period. The Holocene is represented by alluvial and aeolic deposits. The following deposits belong to this period: a. The 1st Euphrates terrace represented by sands, clays, gravels and conglomerates (thickness 27 - 35 m; height 2 - 3 m above floodplain). b. The floodplain of the Euphrates represented by sandy loams, sand, gravel and pebbles. c. The Is Balikh terrace built up of brown loams, mixed with some gravel and pebbles of limestone and flints (tickness 5 - 10 m). There are intercalations of sandy loams or clay layers. 39 d. The floodplain of the Balikh with brown clays. e. Aeolic loam covering the Euphrates terraces, the proluvial and aeolic gypsum deposits and the fine pyroclastic products of the volcano Mankhar Gharbi. f. Aeolic gypsum deposits covering the proluvial gypsum deposits. g. Proluvial gypsum accumulations on the Quarternary terraces of the Euphra- tes. h. Colluvial calcareous and/or gypsifereous grey loams in the valleys of the escarpments with exposures of Miocene rock, i. Lava flows of the Mankhar Gharbi volcano. Sedimentological characteristics and origin of some of these deposits are dealt with in chapter IV.

Fig. '. Mankhar Gharbi volcano.

3. GEOLOGICAL HISTORY

The geologicaL history can be subdivided in three qualitatively different

40 stages : a. Depositing of Upper Cretaceous and Palaeogene carbonate rocks in a basin of normal salinity and open marine conditions (Thetys). Sedimentation during the larger part of the Palaeogene occurred under conditions of smooth tectonic movements under which descending ones were predominant. Upward tectonic movements are marked by the occurrence of wash outs and conglomerates. The uniform sagging kept on until the end of the Oligocène, noticeable in the uniform massive limy sediments. b. During the Aquitanian a rising tectonic movement resulted in a stop to accumulation of the Oligocène deposits. In the Helvetian there was sedimentation of organogeneous limestone and other offshore terrestrial sediments in shallow water. In the northern part of the North-West Syrian Uplift (Hama-Aleppo area) sedimentation kept on with the result that the uplift enlarged, and for the first time the Mediterranean and Mesopotamian basins became isolated from each other, only connected by a strait north of this uplift (north of Jarablus). During several short periods the above mentioned basins were separated; this is reflected in the lithology of the lagoonal sediments. A poor connection of the basins or disconnection gave rise to deposition of gypsum; on the other hand a connection resulted in deposition of limy sediments. During the Tortonian the rising of the Tuwal al Aba area and the formation of the Euphrates depression took place. c. During the end of the Miocene there was a rising tectonic movement, giving a transition to a continental stage. The beginning of the Pliocene was a quiet period with local sagging and the formation of small and shallow inland basins. The rising kept on during Quarternary periods giving rise to erosion of the older Miocene and Oligocène strata and formation of Pleistocene terraces. The valley of the Balikh was formed at the start of the Upper Pleistocene. The Balikh at that time flowed to the west, north of Hazimah, and via the Wadi al Fayd to the Euphrates valley. At the end of the Upper Pleistocene, the- course of the river changed to its recent stage due to tectonic movements. At this time the Mankhar volcanoes were in the first stage of their development. This volcanism can be seen as a continuation of basalt extrusions along the Main Euphrates fault stretching from the north-west to the south-east and in the area buried under Quarternary deposits. 41 During the Holocene the Euphrates changed from a rapid river with much gravel deposition into a meandering river with sedimentation of more fine-textured material; the 1st Euphrates terrace was formed at that time. In recent times the floodplain and riverbedding were formed due to a de- gradation of the Euphrates on account of increased erosion in its own riverbed.

B. Morphology

The oldest component of the topography is the Syrian Plateau, a Lower Pleistocene denudation plain, formed on the Upper Eocene to Pliocene sediments.

The surfaces of the alluvial and the denudation plain gradually merge into each other. Distortion of the plain topography was caused by subsequent uplifts providing downcutting of the Euphrates valley. The areas of development of the Middle and Upper Pleistocene erosion types of topography generally coincide and show that there was a relative tectonic stability. The relief forms can largely be considered to be inherited from the Pleis- tocene, since Holocene climate was practically as arid as it is today. Relief is a function of rock type, tectonical processes, climate and time. The relation between the faultsystem and the course of :.ivers in part of the Jazirah is indicated in fig. 8.

The south-southwest—north-northeast and southeast-northwest direction of the faultsystem has determined the course of the rivers. The main Euphrates fault is accompanied by basalt effusiva.of Zalabyah and the Mankhar volcanoes. North-west of Zalabyah this fault is buried under' Quarternary deposits. The escarpment with Miocene sediments near Hazimah marks the continuation of this fault. The Wadi alFayd is also accompanied by an escarpment with exposed Mio- cene. The Euphrates first following some fault lines continues its course downslope the Northwest Syrian uplift and near Raqqa along a secondary fault of the main Euphrates fault which is marked by a steep escarpment with a maximum slope of 110 m per km. The Syrian plateau is lying here some 100 m above the Euphrates Lowest terrace. 42 '-C'-H basalt

Fig.8. Fault system and course.of rivers in part of the Jazirah. Indicated are the course of the Euphrates and tributaries, main faults ( - - ) and basalt.

Pleistocene terraces are preserved on the left side of the Euphrates valley. The Middle Pleistocene terrace T3 is lacking in the Raqqa terrace region and intensively eroded and reworked in the Hamret terrace region (fig. 9). The Raqqa terrace region is part of the "Island", a triangular area, formed by incision of the Balikh and the Euphrates. The Balikh can be divided in its old course, the Wadi al Fayd, and in its recent course, the Nahr Balikh. During the Upper Pleistocene the Balikh continued its course to the Eu- phrates valley along the Wadi al Fayd fault. At the end of the Upper Pleistocene the river changed its course near Ha- zimah to the eastdue to tectonical instability alongthe Main Euphrates fault. This 43 instability can be related to the activity of the Mankhar volcanoes which came into being at that time. The "Island" was rising, as is proved by the escarpments along the main Euphrates and Wadi al Fayd faults. The higher situated terrains north of the "Island" drained via the Nahr Balikh and Wadi al Fayd leaving the lower Pleis- tocene terrace on the "Island" almost without eroding. This terrace served as a collection reservoir fer drainage water. The drainage water eroded on its way to the Euphrates most of the Middle Pleistocene terrace. This terrace is preserved to the east and west of the "Is- land". East of the "Island'Mn the Hamret terrace region where the terraces were not protected against drainage of higher terrains, the Lower and Middle Pleis- tocene gravel is intensively reworked and deposited on the Upper Pleis- tocene . Rising tectonic movements resulted in deep incision of the Upper Pleis- tocene terrace. During the Holocene the Euphrates changed from a rapid river with gravel deposition into a meandering river with deposition of finer textured material. In recent times the Euphrates degraded to a lower level due to increased spring floods and decreased supply of debris. So the flood plain formed. The banks and plateaus adjacent to the Euphrates river are very rich in flint tools. Van Liere (1960-1961) dated them to be Upper Paleolithic to Neolith- ic or probably later. The age of the floodplain is dated with the aid of antiq- uities . The result of climatic action on rock is dependent on consistence and mineralogical composition of rock. Therefore, as a first approach to morphological characteristics of the region, the relief of the different rock types can be studied. The characteristics of the various landscapes in the Balikh Basin are given below. The location is shown on the morphological map fig. 9. Topographic features of the terrace region are indicated in this map. Pro- files are constructed giving details about relief, thickness of soil cover and soil horizons, They are given in appendix II.

44 1. EUPHRATES TERRACES AND FLOOD PLAIN a. Flood plain.

The elevation upstream is 240 m and downstream 230 m, its slope gradient is 36 cm per km. Terrace meanders formed, cutting downvalley owing to an accelerating force derived from the general slope. The most characteristic feature of the flood plain is the great number of shallow channels the so called "flood plain scour routes" only used during spring floods. Dunes of a few meters high have developed in sandy deposits. Riverbed and flood plain have a Post-Medieval age (v.Liere 1960-1961). b. Holocene terrace or lowest terrace (T^), lying approximately 3-7 m above the flood plain and being 3,5 to 7 km wide. Its topography is rather flat. Occasionally dunes of a few meters high developed on the sandy ridges of point bars. Drainage of the high terraces takes place by relatively deep gullies (3-6 m) which are dry in summer and have their outlet at that time a few meters above the waterlevel. In winter and spring time when the gullies often contain water, the Euphrates river level is a few meters higher than in summer (a maximum in spring time of 3m). The Balikh continues its course through the terrace and discharges into the flood plain at two places. South of Hamret Naser the Balikh follows an old meander of the Euphrates. The slope gradient of the lowest terrace is equivalent to that of the flood plain and terrace meanders cutting down valley are found. These terrace meanders are indicated on the morphological map where the difference in elevation was 2-3 m. Point bars are typical for the Lowest terrace region. They are clearly visible on the aerial photographs due to contrast in color between the ridges and sloughs. Chute cutoff resulting in isolation of a part of a point bar, and neck cutoff resulting in preservation of a complete meander are clearly visible on the aerial photographs. An erosional speed of 70 meters a day has been observed 45 locally. Oxbow lakes containing water during the whole year are present at the southern side of the Euphrates valley. The lowest terrace is prehistoric up to Byzantine (v.Liere 1960-1961) c. Pleistocene terraces. c.l. The if1 Euphrates terrace or Main gravel terrace (T2) lying 15-28 m above the flood plain and having a thickness of 12-22 m.

The boundary between T2 of the Hamret terrace region and T^ is marked by a 12-15 m escarpment, while the transition of these terraces in the Raqqa area is more gradual. c.2. The III Euphrates terrace (T„) is lying 30-50 m above the flood plain and has a thickness of 10-25 m. The boundary between Tg and T_ is marked locally by an escarpment of 15 m. c.3. The IV Euphrates terrace (T.) is lying about 65 m above the flood plain and has a thickness of approximately 10-15 m.

T2 and T of the Raqqa terrace region have a rather flat topography.

Fig. 9. Legend morphological map. ^k*^*v Perennial river. *<* Ephemeral river, wadi. *" - Boundary of morphological regions. Topographical boundary. .•.'. Dolines. « Tal. <& Village. t^J Area with human activity. Fl PI Flood plain of the Euphrates. Tl Lowest Holocene terrace of the Euphrates. T2 Upper Pleistocene terrace of the Euphrates. T3 Middle Pleistocene terrace of the Euphrates. T4 Lower Pleistocene terrace of the Euphrates. BT1 Holocene terrace of the Balikh. BT2 Upper Pleistocene terrace of the Balikh. G Gypsum. L Limestone. M Marl. V Volcano Bas Basalt. Lapfl) Lapilli. F Foggaras. R Water reservoir. K Karst.

47 Escarpments mark the transition to Balikh and Euphrates and the transition of T.to T_. Miocene sediments are exposed in the north-eastern scarp of T. to the Balikh. West of Raqqa the transition of T to T is more gradual. The terraces of the Hamret region have a very hilly topography due to an intense erosion. Wadi Hamret Naser is getting drainage water even from the Gypsum region. After formation of the Upper Pleistocene terrace there has been an erosive period as is indicated, among other things by the valleys in T_, the incision of the Balikh and the formation of the Holocene Euphrates valley. Some flat patches in the Hamret terrace region can be encounterend east of Hamret Naser and at the confluence of several wadis feeding the lower course of Wadi Hamret Naser. The terraces are covered with a loam mantle. Escarpments and tops of hills are built up of gravel.

2. BALIKH TERRACES AND FLOOD PLAIN

The Balikh valley from Hawije to Hazimah is about 4 km wide and below Hazimah 1 km. This narrow lower course and the occurence of medium shallow soils indicate the young stage of formation. Deeper soils are found in the large mouth into the Euphrates valley. This probably is an old meander of the .Euphrates.

a. Flood plain.

a.l. Traject Hawïje-Tal es Samen.

Drainage water of the adjacent high lands is divided over two streams the Nahr Balikh and Wadi al Kheder. The Wadi al Kheder gets its water mainly from the Wadi al Himar, a wadi streaming north of the limestone plateau and coming from the eastern high lands. Also the Wadi el Burj is a tributary of the Wadi al Kheder. Transporting power of the Wadi al Burj can be significant after torrential rains as is shown by the numerous limestone blocks in the lower course. The Nahr Balikh is connected with the Wadi al Kheder near Hawije and is feeding this wadi. The Qara Mokh is an important tributary of the Nahr Balikh, having supply of drainage water from a relatively vaste area. 48 The incision of the Nahr Balikh and Wadi al Kheder in the Lowest terrace is respectively 4-5 m and 3-5 m. The Nahr Balikh is meandering in a flood plain of about 150 m width. The flood plain of the Wadi al Kheder is about 50- 80 m wide. a.2. Traject Tal es Samen-Hazimah.

The valley widens into a broad plain at the confluence of old and recent Balikh valley. Depth of incision and width of flood plain of Nahr Balikh decreases due to capture of water for irrigation purposes (incision only 0,6 m). Near Hazimah canalization of the Balikh was necessary to prevent a diffuse river pattern with great waterlosses. a.3. Traject Hazimah— Raqqa Samra.

The Nahr Balikh recovers from its waterlosses after the confluence with the Wadi al Kheder and the tributary Wadi Hafsir. The incision of the floodplain rapidly increases from 1 m near Hazimah to about 3 m down stream. b. Holocene terrace or lowest terrace (BTj).

This terrace is a flat down valley sloping terrain. The elevations near Hawfje and Raqqa Samra are respectively 305 m and 241 m. The slope gradient over the traject Hawïje-Hazimah is 120 cm per km and that from Hazimah- Raqqa Samra 70 cm per km. The terrace is built up of brown loams with a thickness of more than 3 m. In the northern part marls are outcropping. Between Hawfje and Hazimah there are several tals. The erosion rests of the adjacent terraces in the lower course have been inhabited also. Tal es Samen is about 20 m high above the terrace. The tals initial- ly started as dwelling places on higher parts in the Balikh valley, this being useful for protection against high spring floods. They have grown upwards on account of the materials left by the successive inhabitants. Recent villages have been built also on the higher parts of the Lowest terrace.

49 c. Upper pleistocene terrace (BT ).

Rests of this terrace are found on the right side of the Balikh valley. It is built up of gravel and underlain by proluvial gypsum on limestone. Outcrops of limestone are found on the higher hill tops. The terrace is lying 5-25 m above the lowest terrace and is about 5 m thick. Breccious material at the foot of the limestone massif will have the same age.

3. VOLCANO REGION

The volcano is situated in the centre of this area with many ash piles in the crater. These piles have an elevation of 400 m, that is about 160 m above the terrace level. The bottom of the crater has its lowest point at 120 m below the top of the highest ash pile and the crater sides rise about 100 m above the surrounding lapilli. The sides become very steep near the edge of the volcano. A subcrater formed on the southern slope of the crater. In the first stage of formation an extensive cover of lapilli formed on the terraces. The thickness of this cover at some distance of the volcano is 6-12 m, a fact concluded from deep borings. Mega-ripples have been formed by wind action in the coarse-textured lapilli. This is clearly visible on the aerial photographs where a striage with dominant north-south direction was observed. This preferred direction will be due to the predominant western winds. The topography of the lapilli region is slightly undulating and determined by numerous shallow valleys and small isolated hills. The drainage pattern is more or less radial from the volcano out to the lower terrains, but becomes rather diffuse in the lapilli. In some places the substrata are pressed upwards and domes formed rising about 11 m above their surroundings. The lapilli in these domes is cemented by gypsum and lime. In the II stage basalt streams have flown over the edge of the crater at the northern and eastern side. They have a maximum extension of 4 km and a thickness of 6-10 m (deducted from the topographical map).. Some valleys formed in this basalt and the surface is covered with basalt blocks.

50 Fig. 10. Kaistvalley; collapse sink developed in gypsum.

Therefore, the gypsum deposits weathered to clastic deposits with angular grains by chemical and dominant physical weathering. The gypsum can go easily into solution and crystallize to a dense mass. The formation of crystalline gypsum in places where water comes to a standstill in wadis will be the first stage of karst development. Gradually solution and recrystallisation of gypsum sand will increase. The zone of recrystallized gypsum will gradually move downward and a doline forms with gymsumstone at the sides.

5. LIMESTONE REGION

The north-northeast—south-southwest direction of the Balikh fault has influenced the direction of most escarpments. In Pleistocene times the limestone region was deeply dissected and no karst was formed. The surface of the rock was only slightly attacked by chemical solution. The deep incision and lack of karst may be due to a poorly developed jointing system. These limestones are not folded intensely and therefore will not have been subject to high stresses, giving rise to pronounced jointing. Highly jointed limestones are found in the folded areas of the Libanon ranges and Turkish mountains. 52 4. GYPSUM REGION

This region is bounded to the north by a limestone massif, to the west by a 20m escarpment to the Balikh and the gypsum is overlain in the south by gravel of the Lower Pleistocene terrace. The gypsum deposits have a sandy texture and locally clay layers are intercalated (for further details one is referred to chapter HI, D, 2 and IV, 2). The Pleistocene gravel has protected the softer gypsum deposits. When the Balikh changed its course at the end of the Upper Quarternary, some north-south draining wadis were captured by the east-west draining Wadi Hafsir. The present-day direction of drainage is from east to west except in the extreme south where wadis drain towards the Euphrates valley. Human activity has influenced the morphology in some places e.g. foggaras in the Wadi Hafsir, and Tal Jebel el Udwaniya. The valleys of the Gypsum region are typical karstvalleys. A karstvalley is a transitional stage between surface drainage and underground drainage. (Thorn- bury 1954). Dolines as wel as collapse sinks occur. Dolines develop slowly downward by solution without physical disturbance of the rock in which they are developing. Collapse sinks are produced by collapse of rock above an underground void. Several karstic features, such as bridges, natural tunnels and swallow holes were observed. Caverns do occur at the Euphrates escarpment outside the region. In one of these gypsum stalactites have developed. No karst has been found in the Limestone area. The Lower Quarternary proluvial gypsum deposits are relatively stable since they have survived the pluvial Pleistocene periods. During the Pliocene-Pleistocene the Tertiairy deposits were attacked heavily by erosion forces. The limestone weathered to a calcareous loamy residue (chapter HI, D,l). Much of the calcium carbonate has gone into solution and has been transported as calcium bicarbonate with the drainage water to the sea. In pluvial times there must have been a quite luxurious vegetation on the weathered limestone resulting in a leaching of carbonates. This can not have been the case with the gypsum deposits, having a deficiency in plant nutrients.

51 C. Hydrology.

Hydrology as influenced by climate, geology, morphology and human, activity is discussed below. Human settlement is restricted to the coastal regions with higher rainfall and to the regions with easily accessible drinking water e.g. the oases of Alep- po and Damascus, the rivers Orontes and Euphrates. Central and south-east Syria have a low precipitation and limited groundwater source and therefore a very small population.

1. HYDROLOGY OF SYRIA

The curves of equivalence of aridity indices given by Abd al AI coincide withe the major hydrographie regions., These curves are shown in fig. 3. The 25 index curve encloses the basin of Lake Antioch. The 15 index curve corresponds to the watershed between the areas of sea- ward and inland drainage in the west. Thence it runs northward and swings east over the source regions of Khabour and Balikh. The 5 and 10 index curves are the boundaries of the Dead Sea basin in which the Damascus basin is included climatologically. The 4 and 5 index curves delimit a waterless basin opening soutward.

The present hydrological pattern shows few;perennial streams. The limestone massifs in the Libanon and Turkish mountains serve as water stores. There is rapid run-off as a result of the heaviness of the downpours, however, part of the rainfall is captured by the many fissures and karstic features of the limestone in these mountains. Perennial rivers such as the Euphrates and Orontes have their water supply especially in summer from such catchment basins. Also the closed basins of Damascus and Aleppo are watered by streams fed by great storage massifs. The Euphrates flows over about 540 km of Syrian territory. The average water level in the river at the Turkish frontier is 326 m and at the Iraqian frontier 170 m. Nearly all the water originates from the Turkish mountains in the north while in the desert there is only occasionally some superficial supply. In spite of withdrawal of water during summer for irrigation purposes there is still a relatively high amount of water due to a supply of groundwater between

53 Deir ez Zor and Abou Kemal.

2. HYDROLOGY OF THE BALIKH BASIN

The Balikh Basin is lying in the Euphrates Basin, draining towards the Persian Gulf. a. Superficial water.

The average discharge of the Euphrates near Deir ez Zor is 735 m3 sec. The minimum, maximum and average discharge of the Balikh at the confluence with the Euphrates are respectively 0-5, 12 and 6 m'Vsec. Rainfall in the upper course of the Balikh is 452 mm at Urfa and summer is nearly dry. Some sources near the Turkish frontier supply water during the dry summer too. Difference of water level between summer and high spring floods is about 3m in the Euphrates river. However, in early historical times the water level was higher than it is today. A Roman channel on the southern border of the Euphrates, 20 km west of Raqqa, had its inlet at about 256 m while the level of today in that place is 246 m. The inlet of the channel of Haroun al Rasheed was at a height of about 250 m where the present day water level is 243,6 m. This channel stems from Abas- sid time about 800 A.D. and its inlet is situated at about 12 km west of Raqqa. The lowering of the river level in historical times will be due to an increased erosion of the Euphrates in its own riverbed as a consequence of increased spring floods and decreased supply of valley debris. The spring floods are more pronounced owing to a quicker melting of snow in the Turkish mountains. The terrace and proluvial gypsum deposits drain towards the Balikh and Euphrates valleys. Wadi Hamret Naser has a vast collecting-reservoir of drain water, evidence of an impermeable underground. This could be due to the presence of Pliocene clay and cemented gravel in the substratum.

54 b. Chemical composition and depth of groundwater.

The depth of the groundwatertable can be estimated by the depth and condition of wells. Approximate depth of groundwater: . . Euphrates region about 5 m. Lower Balikh region 5-10 m. Pleistocene terraces more than 20 m. Volcano regions 25-30 m. Gypsum region 15-30 m. Limestone region 20-30 m. The depht of wells indicate a lowering of the watertable. Most wells are salty even in the Euphrates valley. However, fresh water may occur in the valleys of Euphrates and Balikh. The groundwater of the flood plain of the Euphrates is of the hydrocar- bonate type while the groundwater of the lowest terrace is of various composition. There are no wells in the middle Balikh; the water is supplied by the Nahr Balikh and Wadi al Kheder. Depth of groundwater can be only a few meters during spring and winter time in the Lower Balikh and Euphrates. The Hamret terrace is only populated in the south. These people get their water supply from the Euphrates. The Pliocene underlying the terraces and volcanic deposits is characterised by a magnesium-calcium-sulphate type of groundwater (content of salts 1,5-2,8 gr/1). The lagoonal Miocene is characterised by a mixed sodium-potassium- chloride-sulphate type (content of salts 3,2-6,5 gr/l) of groundwater. So far the basaltic rocks have not very much influenced the chemical composition of the groundwater. The most favourable water type is the groundwater of the flood plain of the Euphrates. c. Storage and use of water by man.

The Balikh Basin was inhabited long before B.C. as is proved by the presence of tals in the Balikh valley which have been built up between 2500- 5600 B.C.

55 Raqqa's history dates back to Alexander the Great. In Roman time technique of storing water in cisterns was developed. Larger underground water reservoirs built up of stone are still in good condition in the Roman ruins of Rasafah. Human activity to store water is also pronounced in the Balikh Basin. In the past foggaras and a large surfacial waterreservoir were constructed (see fig. 9). The fogarra consists of a number of shafts at more or less regular distances in a wadi driven to an impermeable layer and interconnected with each other by a tunnel. In recent times earth dams have been built in water-rich valleys (near Tal es Samen) and near springs (Ain Isa and Ain Arus). The stored water is used for irrigation. Wells dug with a diameter of 3-5 m are being constructed in the lower Balikh and Euphrates valley. They are used for irrigation purposes. Wells with a diameter of 1-1,5 m have too low a capacity for irrigation, and supply water for domestic needs of a family and for livestock only. Pumping of Euphrates river water for irrigation of low and high terraces is practised extensively.

In spite of human effort to overcome excessive dryness of the climate, man has not succeeded in becoming independent of the unfavourable climate. A short term drought like that during 1955-1962 caused a depletion of fresh water reserve in many parts of the country. Many abandoned villages in the Jazi- rah bear witness of the shortage of drinking water. The reserve of fresh water is decreasing owing to the increasing number of wells and pumps, and the increased population with a higher standard of living and better technical resources.

56 CHAPTER m

MINERALOGY

Mineralogical analyses can be used for the determination of the homogeneity of the soil profile and contribute to the distinction of soil-forming processes and the determination of soil fertility (Doeglas 1960). However, to be able to appreciate the soil forming processes it is neces- .sary to have knowledge of the mineralogical composition of the various grain size fractions. For this purpose these fractions were analysed by different methods, viz. a. X-ray diffraction, giving the kind of minerals, by determining the specific crystal patterns; b. X-ray fluorescense, giving the chemical composition of the fractions; c. microscopic study, also giving the kind of minerals. These analyses were applied to various fractions: 1. the clay fraction smaller than 2 p. by methods a and b; 2. a small number of selected samples the fraction 5-10 n by methods a and b; 3. another small number of selected samples the fraction 20-30 M> by method b; 4. the sand fraction 50-500 n was studied by method c (heavy and light minerals). 5. the total fine earth, that is soil material smaller than 2 mm, was analysed after method b, showing most of its chemical composition. The mineralogical composition of the different fractions is discussed below while the data of the X-ray fluorescence examination are presented in chapter VUI. 57 A. MINERALOGICAL ANALYSES OF THE SAND FRACTION. (50-500 g,) 1. ANALYTICAL METHODS

The pretreatment of the samples was done after the following standard method. The fine earth was treated with 30% hydrogen superoxide and 0, 2 N hydrochloric acid, after which the fraction 50-500 n was separated by sieving.

Heavy and light minerals were separated with the aid of bromoform (s.g.2,9) The heavy minerals were mounted on a glass-slide with the aid of canada- balm (n= 1, 537) at a temperature of 130°C. They were determined and counted under the polarization microscope. For light minerals this was done in a liquid nitrobenzol with n= 1, 552. The use of nitrobenzol was proved to be useful for determining the plagioclase feldspar in having about the same refractive index as intermediate plagioclase. The magnetic fraction of some samples was examined by X-ray diffraction.

2. PROBLEMS IN CONNECTION WITH THE METHOD USED

The soil material of the Balikh basin is very rich in minerals which easily dissolve during the pretreament of the samples. Preliminary observations proved that the soils contain larger to smaller percentages of calcite, gypsum, anhydrite and olivine. These minerals partly (disappeared I during the pretreatment or the shape of the minerals was highly transformed. The gypsum crystals disappeared largely while the remaining dehydrated after drying the sample at 1O5°C, into hemihydrate CaSO4. |H2O. Dehydration of gypsum takes already place at about 38°C. To estimate the real amount of gypsum, drying should to be done at 35°C and HC1 cannot be used owing to the high solubility of gypsum. Nevertheless, some gypsum will be dissolved already in the aqueous suspension of the soil.. From an original content of about 40% olivine of the heavy fraction only 10-20% is supposed to be left after treatment. Therefore, the estimated percentages of the easy soluble minerals should be evaluated as being much higher on the original sample. These minerals are found after treatment only when the original content is high enough to survive dissolution. A uniform treatment with exactly the same amounts of diluted HC1, diluted H„O2 and fixed time of boiling for each sample could be a theoretical solution 58 but this cannot be realised in practice owing to the varying content of organic matter, lime and free iron. However, in order to get an idea about the content of easily soluble minerals, samples were treated with H2C>2 followed by drying at 35°C, only. Olivine appeared to be considerably less corroded; the same was true for anhydrite; calcite was found to be a common constituentof the soils and had a weathered appearance; nepheline was found only in lower amounts.

Some soil samples were selected of a gypsiferous area and particular attention was paid to the dissolving fraction. The results after different treatments are given in table 13. The profiles 1 and 3 have a soil horizon with accumulation of pedogenetic gypsum, characterised by euhedral crystals. Profile 2 has below the subsoil a soil horizon with geological gypsum, characterised by slightly weathered oolitic gypsum crystals. In case samples got a pretreatment with H2O2 and HC1 and drying at 35°C, most of the gypsum was dissolved, whereas calcite completely disappeared.

Table 13. Percentages of easy weatherable minerals after HC1 treatment and after H O treatment only.

Sample Heavy Fraction 50-500^ Light Fraction 50-500^1 % Anhydrite % Olivine % Gypsum % Calcite nr. HC1 HC1 HC1 HC1 H2°2 H2°2 H2°2 H2°2

1 I tr 40 4 5 0 8 0 tr 1 II 6 40 7 14 tr 14 0 12 1 III 3 20 1 2 tr 47 0 4 2 I 4 30 16 22 0 5 0 10 2 11 3 23 9 20 2 63 0 4 2 III 5 30 10 17 50' 86 0 0

3 I 3 36 12 21 0 7 0 24 3 II 2 45 4 12 0 5 0 31 3 III 1 28 2 21 0 16 0 20

4 I 0 3 75 76 0 0 0 26

Note: 'newly crystallised out of oversaturated solution. Although the original content of olivine is higher than after HC1-treatment, 4 I shows an equal percentage of olivine after HO treatment. This is due to the fact that in this sample many olivine grains have an iron-coating, thus becoming opaque and not determinable after HO treatment. 2 2 59 3. PRINCIPLES AND METHODS OF HEAVY MINERAL RESEARCH

The principles of the so called "Dutch School" were applied. Originally they were enunciated and elaborated by Edelman, and afterwards completed by Doeglas. The most important principles and definitions are as follows. A "sedimentary petrological province" is made up by a group of sediments, which constitute a natural unity by age, origin and distribution. A province can exist out of several different associations. An "association" is the combination of minerals by which a sediment is characterized. So called "chance variations" will occur regularly. There are two types: 1. The distribution of minerals is not uniform in sediments, not even in sediments of homogeneous origin and texture. Therefore, the mineralogical composition of one association can vary within certain limits. 2. Inaccuracy of the analysing technique (see section 2). "Granular variations" are caused by differences in grain size e.g. fine sand will be rich in fine grained zircon and tourmaline, and coarse sand will be rich in coarse augite, diopside or olivine. "Provincial succession": progressive denudation in the source area leads to deposition of an association of new minerals on the older association, separated by a transitional zone with irregular variations. "Provincial alternation": borderline between two sediments, covering each other in turn over a given area. The various soil mineralpgical investigations were carried out in the material of the first one or two meters of the earth's crust. To evaluate the pedogenetic processes which play the most important part in the top layers, it will be important to know the state of weathering of the parent material and what are the changes which took place in the soil in situ. In the case of arid soils pedogenetic processes can be evaluated by studying minerals formed or accumulated in Post-Pleistocene times. For an understanding and explanation of the soil-forming processes it is important to know the homogeneity of the soil profile. In the topsoils where the greatest weathering of soil minerals takes place, admixtures transported by wind can be encountered. Highly mixed topsoils can be regarded as compound provinces, having an admixture of minerals from the surrounding mineral provinces depending on the prevailing wind direction. Soil fertility is a function of the mineral richness of a soil. Study of both 60 heavy and light fraction will be necessary to evaluate soil fertility.

4. DESCRIPTION OF MINERALS

The general descriptions of minerals are given in the textbooks of Heinrich (1965), Milner (1962) and Kerr (1959). In the review given below the special characteristics and varieties of several minerals that occur in the Balikh Basin are given.

a. Heavy minerals.

Zircon often irregular habit, occasionally rounded. Tourmaline, the variety schorlite with pleochroism from light grey to grey or nearly black, from pale green to deep green, from pinkish to black. Garnet, the varieties pale pink spessartite, pink to light red pyrope and colourles to yellow gros- sularite in variable amounts, sometimes also brown melanite in low amounts. Often inclusions, relatively large grains. Spinel, the variétés brown picotite, occasionally colourless spinel, light green pleonaste and dark green hercynite. Zoisite: distinction was made between zoisite with normal interference colours and abnormal interference colours. Fe-rich zoisite, having normal interference colours and a higher birefringence than normal zoisite occurred in lower amounts. Thulite with pinkish pleochroism occured in a few samples. Clinozoisite has oblique extinction. Distinction could be made between clinozoisite with normal interference colours and abnormal interference colours. Fe-poor clinozoisite has larger extinction angles than clinozoisite. A yellow green 1st order interference colour is highly characteristic for clinozoisite. Clinozoisite with normal interference colours is far more common than the other varieties. Epidote has relatively large strongly weathered angular grains, weakly pleochroic from colourless to greenish yellow. Bright and purple interference colours are highly characteristic; occasionally twinning. Pyroxenes: the term clinopyroxenes was applied to diopside, augite, pigeonite and aegirine, only titano-augite has been indicated in the table separately. Diopside was relatively fresh and colourless to pale green, occasionally twinning. Augite is more weathered and more yellow green as compared with diopside; also light brown types and weakly pleochroic. Augite of the Volcano area has prisms with bipyramidal terminations, low birefringence, biaxial positive 2V=60u, often zoned; often in cluster of 5 or more crystals. Titano-augite is weakly pleochroic and has characteristic brown, purple or reddish colours. Pigeonite is more strongly weathered than augite; clear bright interference colours; 2V small 0-32°. Amphiboles: distiction was made between green hornblende, pleochroic from yellow to green or light grey green to grey green, and brown hornblende pleochroic from yellow to brown. Occasionally twinning of green hornblende. Uxynornmende nas a higher birefringence and is more strongly pleochroic than brown hornblende; opague borders or inclusions. Glaucophane weakly to strongly pleochroic in bleu and purple colours. Grunerite, anthophyllite, tremolite, actinolite and cummingtonite occurred in lower amounts and therefore have been registered as accessory minerals. Olivine, mainly forsterite, colourless, sometimes yellow to green. Pleochroic fayalite occured sporadic. Grainsize often relatively large. Phenocrysts often have inclusions of augite microlites. Pene- tration twins occur, biotite flakes are sometimes attached to the grains. Olivine derived from basaltic rock often has a brown or black iron coating.

61 Altetite is a weathering product of zoisite and clinozoisite; irregular grains with greyish weathered surface. Saussurite is a weathering product from epidote; greyish colour; on the corners a purple and/or green interference colour. Anhydrite has a higher birefringence than gypsum. Habit mainly denticular, furtheron rectangular, euhedral, fragmental, composite sheaf and oolite types (see fig. 14). Apatite and titanite are registered under accessory minerals.

b. Light m inerals.

Quartz is occurring in mainly subrounded and subangular forms. All main types of quartz were recognized. These are: a. metamorphic quartz with wavy extinction and inclusions; b. igneous quartz, being nearly equidimensional and without inclusions; c. sedimentary quartz, being highly rounded, frosted and with overgrowths; also chalcedony with pseudo-interference figures belongs to this group. Sedimentary quartz is the most abundant quartz type in the region. Volcanic glass is amorphous, colourless but also light greenish grey, often perlitic fracture, irregular, rounded and angular grains occur. The lapilli contained glass with inclusions of augite and a few olivine microlites. The grains of augite and olivine at the time of cooling of the magma were embedded in a mantle of volcanic glass. Phytoliths (SiO.. nH 0) are amorphous plant made materials. Their shape can be related to the place of formation in the plant, (see Chapter V for further details). The grains are transparent and often have a light pink color. They remain extincted during rotation using crossed niçois. Other names are: hydrated silica, opaline silica (Smithson 1956), kieselkörper (Netolitzky 1929) and organic SiO^ (v. Rummelen 1953). Feldspar: Sanidine has a smaller 2V than orthoclase, and is more turbid. Orthoclase is biaxial negative, grains are clear and have often inclusions. Microline has a tweed-like fabric (combined albite-pericline twinning). Acid plagioclase=albite+oligoclase; negative relief in nitrobenzol; biaxal positieve; albite twinning and carlsbad twinning; occasionally inclusions. Intermediate plagioclase=andesine+labradorite; refractive indices near that of nitrobenzol; albite twinning and also carlsbad twinning. Basic plagioclase=bytownite+anorthite; positive relief in nitrobenzol; albite twinning and carlsbad twinning. Sanidine, microcline and basic plagioclase occurred only in small amounts. Muscovite with s. g. = 2, 76-3,0 (Milner 1962), colourless; the grains have a low birefringence owing to their platy character and are generally five times larger than the average grain size of the other minerals. Mainly colourless phengite with 2V=0-20 ; also fuchsite (metamorphic source rock) with a pale green colour. Muscovite occurs in light as well as in heavy fraction owing to its intermediate specific gravity as compared with bromoform (s.g. ~ 2, 9). Gypsum becomes dehydrated during treatment and alters intho hemihydrate. In fresh condition gypsum is often covered by a coating of calcite. For crystal habit and discussion see fig. 14 and section A, 6 of this chapter. Calcite has a high birefringence; hexagonal; rounded or angular habit; weathered appearance in fresh material; goes completely into solution after treatment with 0, 2 N-HC1. Weathering products, distinction is possible between light brown to brown weathering products from gypsum, and grey weathering products from feldspar.

62 5. MINERAL PROVINCES AND ASSOCIATIONS

An abundance of feldspar, mica, gypsum, anhydrite and calcite is generally characteristic for sediments from semiarid and arid climates. Although the content of light minerals generally is more than ten times as high as that of heavy minerals, the mineral association was defined by the heavy mineral assemblage, being the most characteristic of the sand fraction. The Balikh Basin can be divided in the following mineral provinces: 1. Euphrates province; deposition in Hofocene times. The mineral assemblage of the examined surface layer is related to present day sedimentation in the Balikh. 2. Terrace-Balikh province; deposition at the end of the Upper Pleistocene and in Holocene times. The loamy cover of the terraces is supposed to be slightly older than the valley fill of the Balikh. Owing to origin, age and mineral distribution Ter- race and Balikh can be seen as one mineral province, divided in four associations. 3. Volcano province; deposition of lapilli at the end of the Upper Pleistocene. There is a transition to the Terrace-Balikh province, and the surface layers have an admixture of minerals from this source. 4. Gypsum province; deposition at the beginning of the Lower Pleistocene, but in following periods eroded and redeposited for repeatedly times. On the surface deposition of material from the Terrace-Balikh province; the boundary of this material with the underlying gypsum is rather abrupt. As will be clear from the statements made above, the mineral assemblage of the Terrace-Balikh province plays an important part in the top layers of soils from the Gypsum and Volcano regions which is favourable to their agricultural value. The top layers of these soils as well as the transition from terrace to volcano are regarded as compound provinces. Table 14 gives the results of mineral counts of 100 non opaque minerals while the opaque minerals are expressed as a percentage of the total heavy fraction.

63 . TABLE 14: HEAVY HIHEHALS OFTHE BALIKH BASH

Sample Transparent ha&T? minarais 1n nntuB 1 perce nta« s Hr. depth * Light % heavy • S in Bin. of ail . of V g a •a en soil soil *> e 1 te a a < 2 ma •a •r« a a •H e i • -H •H Ü 0 1 0 c *» U s 9 r* M < 0 1 *4 O ** a 8 s s t. +> O « a t. a | S •- 3 0 CD CO I d 1 B 1 1 0 s 0 X Euphrates I

20 I 0-5 8,1 0 .8 7 1 3 1 1 5 20 26 1 11 6 20 1 1 tr 1 1 2 20 II 30-35 0 ,2 0 ,1 7 1 3 1 6 19 11 4 15 12 24 3 tr 1 tr 20 III 60-65 2 ,8 0 ,07 5 2 tr 1 7 30 9 tr 11 2 19 6 1 3 1 1 7 20 IV 85-90 0,02 0 ,003 5 1 1 tr 6 25 8 1 3 6 5 28 3 2 11 33 I 13-20 4 ,6 0 ,4 19 2 tr 9 27 14 1 2 8 5 25 4 1 33 II 40-50 3 ,6 0 ,4 10 5 1 1 4 20 14 3 6 6 35 3 1 1 Balikh

15 I 0-12 0 ,3 0 ,1 30 1 17 1 1 6 19 30 8 5 2 1 1 4 4 15 II 15-25 0 ,3 0 01 28 14 6 15 29 7 1 6 4 tr 6 7 5 15 III 40-50 0 ,2 0 01 24 1 17 tr 1 3 3 14 30 1 6 4 8 4 1 tr 4 3 15 IV 90-100 0 ,2 0 01 26 1 6 2 3 11 36 1 9 1 9 3 tr 11 4 3 27 I 3-7 1 ,4 0 1 32 1 1 11 2 tr 1 1 3 23 25 3 7 1 6 7 tr tr 1 4 3 27 II 20-26 1 ,2 0 ,1 28 2 1 6 tr 1 6 27 19 2 9 tr 11 2 1 2 1 2 6 27 III 47-53 0,5 0,1 21 1 tr 9 1 tr 1 1 12 30 2 11 tr 12 3 2 1 1 6 7 27 IV 77-83 1,0 0 1 26 1 1 6 tr tr 1 1 24 26 2 6 6 2 3 30 tr 4 3 1 4 13 34 1 2 13 1 2 2 1 tr 4 6 9 30-40 0 25 II 2 ,3 2 30 1 4 4 1 3 20 40 5 1 4 2 7 6 7 I 0-10 0,4 0 03 17 1 3 tr 9 29 17 tr 10 1 9 4 52 2 2 1 30—40 Q 7 II 0 02 20 g 8 I 0-4 1 2 0 1 23 2 6 tr 3 26 17 12 4 10 5 2 tr 8 3 2 8 II 5-10 1 3 0 2 34 2 7 tr 7 17 19 1 10 tr 14 5 tr tr 11 5 1 8 III 13-18 1 4 0 1 28 1 10 1 3 19 19 1 11 2 8 2 2 1 10 6 3 1 8 IV 25-30 0 ,8 0 1 33 1 10 1 tr tr 5 15 18 1 13 2 11 5 11 5 1 1 8 V 45-50 0 ,8 0 05 17 1 5 tr 1 2 29 19 1 8 4 10 3 tr 7 3 5 2 8 VI 75-80 3 g 28 24 ? A 12 8 1 tr 1 9 I 0-10 0 6 0 05 13 1 7 1 tr 5 25 3 5 39 4 tr 9 1 1 34 I 0-8 0 3 0 03 33 2 3 5 20 36 1 6 5 10 3 1 tr 2 6 34 II 15-22 0 3 0 01 38 1 6 tr 1 2 17 40 1 12 2 6 3 5 3 1 34 III 36-40 0 3 0 01 32 1 9 4 16 39 6 2 7 5 1 4 5 1 34 IV 60-65 0 ,2 0 01 26 1 3 tr 19 42 9 7 10 4 1 2 2 34 V 85-90 0 2 0 02 29 1 3 tr 1 2 18 35 6 1 10 9 7 3 3 1 Balikh-

19 IV 90-95 0 3 0 03 5 1 1, tr 3 20 16 1 18 8 16 4 2 tr 1 2 4 19 v 140-150 0 1 0 01 6 2 6 1 1 2 2 19 10 2 16 7 21 2 1 tr 4 2 2 Baqqa terrace 24 I 0-8 13 6 1 6 31 1 8 1 1 1 3 16 26 2 12 tr 11 2 tr tr 5 2 9 24 II 8-15 Q 23 22 2 7 tr 7 1 24 lit 15-43 5 3 0 8 33 3 1 1 2 1 tr 3 13 25 2 5 20 1 12 5 3 9 24 IV 71-79 5 6 0 7 34 tr 6 1 1 2 11 18 2 2O 14 6 tr tr 5 78 6 26 I 0-10 3 7 0 1 32 2 12 j 2 1 2 13 19 3 19 2 7 9 tr 4 5 26 II 10-20 2 2 0 2 25 .r tr 8 tr 1 1 1 4 9 27 3 17 tr 13 5 5 9 26 III 25-35 2 8 0 3 40 1 7 1 tr tr 1 1 2 13 32 9 tr 7 3 tr 1 tr 5 17 26 IV 50-60 4 4 0 4 33 1 tr 12 1 tr 1 1 17 31 10 1 7 3 tr 1 1 3 11 1 9 0 2 8 32 II 20-30 29 1 32 III 40-50 1 7 0 1 30 1 tr 7 2 1 2 17 28 1 9 4 6 5 4 .1 4 7 32 IV 70-80 2 9 0 3 40 1 7 5 tr tr 3 18 28 10 11 4 1 1 1 3 6 Hamret

5 I 0-8 n a. n a. 13 1 8 8 11 25 2 13 2 6 3 1 tr 9 4 6 1 5 II 15-25 n B. n a. 13 8 tr 1 15 27 2 12 4 5 4 6 9 6 1 5 III 40-50 n n. n a. 11 tr tr 1 1 4 20 28 tr 10 1 12 7 tr 2 7 1 5 IV 75-85 n a. »• a. 13 S tr tr 2 3 26 30 5 9 5 1 tr 7 1 2 1

28 I 0-10 5 7 0 4 26 2 13 tr 1 1 1 8 16 2 18 2 12 1 tr 4 6 13 28 II 30-40 4 6 0 5 30 3 tr 6 3 4 14 22 1 13 2 9 2 tr tr 8 0 4

29 I 0-10 6 5 0, 7 26 3 tr 7 2 18 17 3 16 3 10 6 1 1 4 5 4 V.lltj fill of O7PB1W region 14 I 0-10 1 2 0 4 26 9 4 2 15 2o 7 9 2 5 11 7 1 14 II 40-50 2, 4 0, 4 26 1 10 2 ;r 7 18 35 S 7 tr 1 8 4 1 Valley fill of Linesto ne regio n 6 I 0-10 0 6 0 1 31 2 8 1 tr 7 21 30 3 tr 9 2 1 6 7 4 6 II 30-40 0 7 0 1 21 2 8 tr tr 3 29 25 1 tr 9 6 tr 12 3 2 Transition Terrace-Volcano 17 I 12-17 2, 5 0, 3 20 1 6 tr 1 2 15 12 1 24 4 9 tr 18 5 2 17 II 32-57 9 7 0, 1 23 1 2 2 7 12 2 46 tr 8 tr 1 10 6 3 62-67 4 20 17 III 3, 6 ot 3 1 6 21 13 1 14 1 16 1 1 1 9 8 4 110-115 2, 0, 21 1 17 IV 3 3 4 tr tr 6 14 18 7 17 2 13 1 tr 10 7 6 tr

64 f I I f I i withou t anhyd r 3 0 v i 83-8 7 3 0 V 58-6 2 3 0 I V 38-U 2 3 0 II I 23-2 7 3 0 I 8-1 2 3 0 I 0- 5 1 3 II I 60-6 5 i. 3 I 25-3 0 L 3 I 0- 5 L O I 30-3 5 L O I 1- 6 ïeav y minerai s L 2 I 15-2 0 L 2 I 0- 5 [1 1 0-1 0 | * I 25-3 5 K 2 I 30-4 0 \z 1 0-1 0 | 6 I V 145-15 5 [ 6 II I 60-7 0 ( 6 I 20-3 0 \€ I 0- 4 lésio n lolcan o 1 I 0-1 0 1 I 40-5 0 ypsu n 3 I 0-1 0 e gio n 3 I 30-4 0 II I 70-8 0 I 50-6 0 I 5-1 0 II I 7O-8 O I 45-5 5 I 30-4 0 V 82-8 7 I 0- 5 i v 83-8 7 II I 38-4 2 I 15-1 9 i 3- 7 S"ü I V 52-5 7 II I 28-3 2 I 10-1 4 a 0 p- 0 B P« 1 rt ? 1 ? D" OTT-OO I A i.X

12, 3 14, 0 10, 1 10, 2 12, 4 A D B M rt .P-^VO -P-ONO -O OOO H OOH Vf ru H O lu \o 0 D H*- 0 H vf ru D D D DDP P P D -r-ff^voru^ Vf VO H O\ H O IU ON HvO H fU 00 B OAO 00O\H ON B B B B B B B B B VWo t % heav y < 2 u m nin . o f soi l

000000 O OOO O O 0 0 O O I\J H 0 D H ru ru H ru ru POP DDP D P D M »-• O H H OOOO B a a a a B B B B *-> fW OSHUI Vf 0^ -^ Vf ru H H Vf • TO O

(U j_, jj jj -» H l\) Vf IU ru Vf tu H H H ru ru ru H ru ru H Opaqu« 0 --J -g 00 00 0 o" 88 38 ru ONvn Vf Vu Vf -N] OOH vn vo Vn vn *" -P~Vf « &Ü £.& Vf *O H -O Vf HVf rt rt rt rt rt t r rt H rt JJHH M H H Zircon »1 *t •ï et rt rt «t rt Tourmaline H H H H 1 H *i H H H H H H Garnet

*"&* < Vn O 0> *1 H 00 O -P""O Vf ru ru Vn tu rt rt rt rt Spinel H H H ï ru H ru H Vf Vn H H H *t H H •1 t t ru »1 rt rt rt rt rt rt ft rt rt Rutile ru tu 1 1 H *t H H *i i»SÎ ,, , Brookite

H Anatase

H H 5taurollte

H Kjanito

1 IU H •*>" H H H Vf Veeuvianite H H ru t-1 »^ Chloritoid 1 3 6 7 2 1 •p-fu ru ru ru Vf ru 00 Vf Vn -p- ru -0 ru H 3 1 9 Zoisite

H H t-> H H H IU H ru H C H H H H H H Clinotoisite fO vu -O G ff •p- H O OO ONH VO ru -J H s O.Vf M H H Vf H H Vf -P-nj iu ru ru ru lu H H H l-> H *-• Epidote «»» OOH Vf HO ru Vn &% *- -p- OOH Vf ru •p-ru vn Vf *- ru vn vn *- ru Vf vn ooooVf H ru H H Estatite Hypersthene

H H H IU H WH Clinopyroxene OOVf H Vf vn *• 00

H *->}-> ru Oreen hornblende ru Vf Vf 0 »-s) vx Vf H -O H OOOO Brovn hornblende 1

rt rt Oxy-ho rnblen d e H ru H H ru H H H H H (U H *t 1 ru H H H rt rt rt rt ÎHH HÎ H H H î H H H rt Qlaucophane *t *1 *1 tus î n rt H H H Vf Vf HVf vn Öl iTino H^Oo-sJ *i ru vn -P- UION v?o Ri vn sa OOVM >J O\ tu *- ru H-0 Vf ru O^> Vf ru »!££<» ru H H t-> t^ h» H H Oojr jr- \O OoVJt ro vn co\o Vf vn vn ON 00 Alterite •P-OO-P- H H Sausourite iu -P-ru ru H *"-0 •P-H ru H W H -r ru ru Vf ru Hvnru n. m n. n n. m ON-O vn Anhydrite H O-O H VU H U VÔ H H H H H Vf Vf Vf H ruv* Variations in the percentages of one mineral within a province or association can be seen as chance variations as defined in section 3 of this chapter. Granular variations will occur in the Euphrates province due to the alluvial character of the deposits with as a consequence variations in grain size between the different layers. The other provinces are quite homogenic in their grain size distribution in the soil profile, so granular variation will not effect the mineral distribution.

The situation of mineral provinces and associations found in the region is given in fig. 11. To illustrate the mineralogical assemblage of the different soil horizons three levels were chosen, these are topsoil 0-30 cm, subsoil 30-60 cm and deeper subsoil 60-100 cm. The heavy mineral assemblage is given for each of these levels in a diagram indicated on the map in the centre of each mineral province and association. Deposits found in the wadis intersecting the gypsum and limestone areas are indicated as valley fill. If the valley fill was different from the surrounding sediment, a diagram is given beside the sketch map.

In order to determine mineral associations, heavy minerals are discussed first, while the light minerals are dealt with in section 5.b. of this chapter. The Holocene basalt, Pliocene marl and Miocene limestone, shown on the map (fig. 11) are discussed in subchapter D. a. Heavy minerals.

The mineral assemblage of the different provinces is given below:

a.l. Euphrates province.

The valley fill of the Euphrates has a clinozoisite-epidote-green hornblende association. The content of clinopyroxene is relatively high. Locally there is a high content of titano-augite. Soil texture and content of heavy and light minerals are highly variable with soil depth. There is a lower content of epidote and garnet, a higher content of green hornblende as compared with the Balikh. The content of clinozoisite is high; only traces of olivine occur.

66 Characteristic are the fresh mineral grains and the low content of opaque minerals, alterite and saussurite, pointing to a lower stage of weathering as compared with the brown loams of the Terrace-Balikh province. a.2. Terrace-Balikh province.

This province is characterized by an epidote-clinozoisite assocation. The valley fill of the gypsum and limestone areas belong also to this mineral association. Four associations were distinguished.

a.2.1. Balikh association.

The Balikh sediment has an epidote-clinozoisite association. Locally there is a high content of green hornblende . The topsoil has a slightly higher content of heavy minerals as compared with the subsoil. The content of epidote and amphibole increases downwards in the soil profile. Present day sedimentation in the Balikh is characterized by a high content of clinozoisite, as has been proved by mineralogical analyses of profiles in the Wadi al Kheder and the lowest terrace of the Balikh (respectively profile 7 and 8). The same is true for sedimentation in the Euphrates. Characteristics of minerals: Olivine from the Balikh province is. more rounded, often coloured and the content of fayalite,' although low, is higher than in the Volcano region and related provinces. Intergrowths between clinozoisite and epidote occur. The garnet often has a slight birefringence and inclusions. Feldspar with inclusions is common. a.2.2. Raqqa terrace association.

The loamy cover of the Pleistocene gravel terraces has an epidote-clinozoisite-pyroxene association. Characteristic is the moderate content of green hornblende, diopside, augite and low content of pigeonite. Garnet is sometimes rather weathered; fayalite occurs in subordinate amounts.

67 O 4 8 km

I Tfaa.l ;O-SOc*. I twMail ; SO-tOCM. BM Oli.ta* I 0««»t' »•»MU i ^^| «O-100 tat. Ocraai §§jSj§l Altanta «n« j^^J tdikh «tt«cl«li«* || | || ^-^ •••••«'"• __ .^.^ is".v::r"" H • ^ ".::::.:;:;••• EZ] o,... ^ : «.....«. v v S tairac* la Fig. 11. Mineral provinces and associations of the Balikh Basin.

Note: The mineral assemblages were defined according to mineral content after pretreatment with H2O2 and HC1 followed by drying at 105° C. Easy weatherable minerals will have gone into solution during treatment. They have been used for classification only where they are the main components of soil.

68 a.2.3. Hamret terrace association.

The same association as for the Raqqa terrace, but a higher content of olivine. Loam near the volcano is highly mixed with lapilli, the influence and size of grains of volcanic material decreasing with distance from the volcano. In order to simplify the sketch map, the. whole Hamret terrace has been considered to have the same content of olivine.

The magnetic fraction of profile 28 was determined by X-ray diffraction and consists of hematite , amphibole , augite , ilmenite , magnetite and wustite; (+= 10-30%; no notation = 0-10%). The group of opaque minerals is mainly built up of hematite and ilmenite, and low amounts of magnetite and wustite. a.2.4. Valley fill of the Gypsum and Limestone regions.

The loamy valley fill of these regions has an epidote-clinozoisite association. The valley fill of the limestone region has a relatively high content op epidote and olivine. The content o f alterite and saussurite is higher in the topsoil than in the subsoil, pointing to a more intensive weathering in the topsoil, owing to water from occasional rains coming to a stand-still in these valleys. a.3. Transitional province from terrace to volcano.

Loam with an admixture of fine-textured lapilli is underlain by gravel, and has an epidote-clinozoisite-olivine association with locally a high content of pigeonite. Towards the volcano the loam becomes highly mixed with volcanic lapilli. The weight percentages of heavy minerals are variable. Augite derived from Upper Pleistocene volcanism is present in all samples; fayalite occurs sporadic. a.4. Volcano province.

The lapilli soils have an olivine-pyroxene association in top and subsoil, while the deeper subsoil is characterised by an olivine rich association.

69 In the upper part of soil clinozoisite and epidote are present in variable amounts while they are lacking in the deeper subsoil. Locally there is a relatively high content of augite. Weight percentages of light and heavy minerals are variable. Olivine from the Volcano province was found by X-ray analysis to be forsterite. The magnetic fraction from sample 22-1 determined by X-ray diffraction • i [ i consists of augite , magnetite , wustite (FeO), hematite (QfFe.O ) and ilmenite; (+++=50-70%; += 10-30%; no notation= 0-10%). It seems likely that part of the opaque fraction is built up of augite microlites cemented together after cooling of the magma, the rest being magnetite, wustite, hematite and ilmenite. Mi- croscopic examination of grinded opaque grains indeed showed microlites of augite and magnetite. The samples analysed were taken on various levels with different topographic features, but there is no mutual difference in mineralogical composition. a.5. Gypsum province.

The topsoil of the gypsum deposit has a loamy admixture with an epidote- clinozoisite association while at greater depth the percentage of anhydrite is high. The transition from loam into gypsum is rather sharp. The content of anhydrite decreases in the deeper subsoil (fig. 12). The topsoil is characterised by a higher percentage of heavy minerals as compared with the subsoil, a phenomenon coinciding with the increase of gypsum downwards in the soil profile and consequently a much higher percentage of light minerals (fig. 13).

The heavy mineral content without anhydrite of the samples 30 IV-VI was determined and compared with that of 30 I-HI. This material is slightly different from that of the topsoil in having a higher content of opaque material, garnet and alterite while the content of clinozoisite is lower (table 14). The material of subsoil and deeper subsoil mixed with gypsum and small quantities of anhydrite has apparently an older age than the material of the topsoil, although the source region will be the same. Recent mixing apparently takes place only in the upper 40 cm of soil.

70 d o d 0

100 0 20 40 60 80 100 %

- profile 30 % gypsum of total sand — profile 13 % calcite of total sand

Fig. 12. Content of anhydrite Fig. 13. Total content of gypsum in gypsum soils and calcite in fresh material ( heavy fraction ) of profile 30 ( heavy and light fraction )

b. Light minerals.

Minerals of the light sand fraction of the provinces defined above are shown in table 15. The main light minerals of these provinces are: b.l. Euphrates province with quartz, chalcedony, acid plagioclase and muscovite; the content of phytoliths being relatively high; chalcedony points to attri- bution of limestone as a source rock; b.2. Terrace-Balikh province divided in b. 2.1. Balikh association with quartz, acid plagioclase and orthoclase; b.2.2. Terrace association with quartz, chalcedony and acid plagioclase; b.3. Transitional province from terrace to volcano with quartz and orthoclase, and volcanic glass occurring in lower amounts ; b.4. Volcano province with volcanic glass, orthoclase and quartz in the topsoil, and volcanic glass as dominant mineral in subsoil and deeper subsoil; the volcanic glass has inclusions of augite microlites, making the grains opaque (the presence of augite was confirmed by X-ray diffraction) ; b.5. Gypsum province with quartz and orthoclase in the topsoil and gypsum as

71 dominant mineral in subsoil and deeper subsoil (for details about gypsum see below).

Table 15. Light minerals of the Balikh Basin.

Sample Light minerals in mutual percentages

c weight _al - is e j läs e percentage S 4>

light on y diät e in g agioc l c glas : c glas : clusio i t e + o ] « S - Lgiocl l giocl a S • -B .3 Depth minerals N 'c ra 'S S » o" =3 8 I pl a

Nr. i d pi s A pheli i cesso i

in of term e .si c p i uscov i 8.E îathe r oduct ! 1 u cm soil<2 mm u |a ïl? O. s2 so aE V E (0 ° ° ° s .s s C S .8 ï S. Euphrates region 20 I 0-5 > 8.1 19 17 4 8. 2 7 23 3 3 6 7 1 20 II 30-55 0.2 13 10 1 10 12 1 22 6 12 13 20 III 60-65 2,8 25 11 3 10 6 14 4 1 2 15 9 20 IV 85-90 0,02 25 10 1 5 12 2 16 4 1 19 5 Balikh region 15 I 0-12 0,3 29 9 3 17 2 22 4 14 15 II 15-25 0,3 33 22 16 1 12 6 9 1 15 III 40-50 0.2 30 13 2 1 16 1 19 10 8 15 IV 90-100 0.2 34 15 1 11 28 5 1 5

7 I 0-10 0.4 28 14 1 13 25 1 1 2 1 14 7 H 30-40 0,3 29 10 1 20 17 7 2 2 1 11 Raqqa ter ace regie n 24 I 0-8 13,6 34 18 11 12 4 1 20 24 11 8-15 1,0 28 19 10 2 18 5 2 1 14 1 24 III 15-43 5.3 34 18 1 1 10 1 15 8 2 1 9 24 IV 71-79 5.6 36 19 1 18 2 16 3 13 1 Transition terrace- rolcano 31 I 0-5 12,4 24 7 2 1 26 6 2 2 26 31 D 10-14 10,2 35 5 3 3 1 16 13 3 21 31 m 28-32 10,1 28 13 3 5 21 1 5 4 1 1 18 31 IV 52-57 14,0 25 15 3 3 25 2 16 2 9 31 V 82-87 12,3 29 14 1 2 23 1 10 1 1 18 Volcano i ïgion 16 1 0-4 2,6 5 6 8 48 16 9 1 7 16 H 20-30 3.1 13 7 9 31 8 1 9 1 1 1 19 16 III 60-70 1.6 4 6 14 33 6 1 7 1 28 16 rv 145-155 0.8 3 90 3 4 Gypsum region 30 1 0-5 6,9 22 8 1 1 18 8 4 13 25 30 II 8-12 6,2 24 10 1 18 3 5 29 30 III 23-27 4,9 26 3 1 13 1 9 3 2 1 27 14 30 rv 38-42 9,4 2 1 2 1 94 30 V 58-62 7,6 2 1 97 30 VI 83-87 4,4 12 3 7 2 74 2

10 1 1-6 1,0 26 5 1 24 15 1 2 17 9 io n 30-35 8,1 2 98

72 6. GYPSUM, HEMIHYDRATE AND ANHYDRITE

Gypsum dehydrates into hemihydrate at a temperature of about 38°C. Hemihydrate has a higher birefringence than gypsum. The crystals are etched and often oolitic after pretreatments with HgO« and HCl followed by drying at 105°C; extinction of hemihydrate parallel to direction of etching. The light mineral fraction of sample 10 II was examined by X-ray diffraction and consisted for about 85% of hemihydrate. After drying at 105°C all

CaSO4.2H2O was dehydrated into hemihydrate CaSO..|H2O. Hemihydrate can be formed only in the upper cms of soil where temperature can reach values high enough for dehydration of gypsum. Only in summer soil temperatures reach values of 42°C at 10 cm depth. Measurements during the summer of 1965 dit not reveal higher values even directly under the surface (0-5 cm), this being due to a high albedo. The reflection of sun rays is especially high in the light coloured gypsum soils. Crystal habit of gypsum is given in fig. 14. Generally fresh gypsum is euhedral or rectangular, but fresh oolitic material was found, the crystal habit of gypsum being often suitable for rounding. Boiling in H_02 and HCl can easily round some types of gypsum euhedra. Therefore, it is necessary to study fresh material before drawing conclusions about sedimentary origin. In one case spherulitic structured gypsum with undulatory extinction was observed. This was not encountered in the same sample treated with H„O alone; both samples were dried at 35°C. Apparently the spherulitic gypsum must be seen as a recrystallisation product of an oversaturated solution during treatment. The percentage of gypsum was determined in fresh material, light and heavy minerals mixed in the sand fraction. This is shown for profile 30 in fig. 13. Anhydrite had a diffraction pattern different from that mentioned in the X-ray Powder Data File 1962, but was determined qualitatively by chemical reactions on Ca (red flame) and SO. (the material gives after dissolving in moderately concentrated HCl a white precipitate with BaClg -solution).

7. WEATHERING OF SOIL MINERALS

Minerals at the time of formation are in equilibrium with their environment, but brought in new environments they tend to decomposition if enough moisture is present.

73 Pathologie features, such as etched surfaces and corroded borders are indicative of instability. For soil genesis the question arises: is the mineral at the place of weathering or did weathering take place elsewhere ? Therefore, it is necessary to have some knowledge of the sedimentological history of the soil building material. Since most soils of the Balikh Basin are alluvial (Balikh and Euphrates) or aeolic (Terrace loams), material is not weathered entirely in the soil itself. Only lapilli soils are practically in the place of primary deposition. According to Hilgard (1906) the most striking difference between residues formed in arid and in humid regions is the relative percentage of insoluble minerals, as are quartz and acid plagioclase.

Table 16. Percentage of insoluble material in humid and arid regions.

% insoluble material humid regions 84 (ace. Hilgard) arid regions 69 (ace. Hilgard) Balikh Basin 56

Conditions of minerals were examined after a pretreatment with H.O_ followed by drying at 35°C or without pretreatments. Quartz has brown coatings and is weakly etched; feldspar has a slightly etched surface; basic plagioclase can be strongly weathered. The crystal habit of olivine, gypsum and anhydrite after pretreatment with H2°2 followed bv drying at 35°C or without pretreatment is given in fig. 14. The percentage of different forms of olivine, .anhydrite and gypsum are indicated in tables 17 and 18. Euhedral and slighty corroded anhydrite crystals often have a corrosion direction perpendicular to the crystal's lenght (001 cleavage), while the corrosion direction of olivine crystals is often parallel to the lenght of crystals (010 cleavage). The original olivine crystals in basaltic material are not or only slyghtly corroded by magmatic action, however, iron-coatings can be present already in the original material. Magmatically corroded grains will more easily weather as is proved by the abundance of iron-coatings, in the more weathered olivine types ; However, iron coatings can be formed during soil formation from the olivine grains also; this will be subordinate under present conditions.

74 olivine

anhydrite

gypsum

Fig. 14. Crystal habit of olivine, anhydrite and gypsum in fresh condition or after pretreatment with hydrogen Superoxide followed by drying at 35° C. Legend olivine : Legend gypsum : 1 euhedral (a + b + c) 1 euhedral 1 euhedral ( a + b ) 2 slightly corroded 2 rectangular 2 rectangular 3 corroded 3 corroded rectangular 3 slightly corroded ( a + b ) 4 strongly corroded 4 strongly corroded 4 denticular and coated 5 fragmental 5 strongly corroded ( a + b ) 5 fragmental 6 oolitic 6 fragmental 6 rounded 7 denticular 7 oolitic 7 penetration twin 8 corroded denticular 9 composite sheaf 10 penetration twin

Table 17. Crystal habit of gypsum in fresh condition without pretreatments (see fig. 14, legend of gypsum)

Sample depth gypsum in % of total fraction 50-500 p. nr cm 12 3 5 6 7 total %

30 III 23-27 3,1 2,3 2,3 7,7 30 IV 38-42 24,4 8,0 6,4 1,3 6,4 48,0 94,5 30 V 58-62 5,2 3,9 48,0 1,3 2,6 28,6 89,6 30 VI 83-87 1,2 9,5 28.6 26,2 17,8 83,3

Olivine and anhydrite are corroded while gypsum is generally strongly corroded in the topsoil . The subsoil is characterized by the occurrence of slightly corroded anhydrite and slightly or strongly corroded gypsum. The content of euhedral olivine is generally increasing downwards in the soil profile. The deeper subsoil can have slightly corroded anhydrite and olivine, while

75 ai

Table 18. Crystal habit of easily weatherable minerals after treatment with HO followed by drying at 35 C of profiles 1, 2 and 3 of the Transitional province from terrace to volcano and profile 4 of the Volcano province.

Sample depth Olivine Anhydrite Gypsum in %of heavy fraction % of heavy fraction %of light fraction

nr cm 1 3 3 4 5 6 1 2 3 4 5 6 7 9 1 2 3 4 5 6 7

1 I 30-40 0,3 1 2,4 0,7 0,3 0,7 21,4 7,5 9,2 4,9 2,8 3,5 8,0 1 II 45-55 7,8 1,3 2,6 2,6 4,0 1,6 13,6 8,0 4,8 6,4 1,6 1,4 9,3 3,3 1 HI 70-80 1,0 1,0 0,9 12,0 4,4 1,8 0,9 1,4 1,4 7,2 1.4 8,6 5,6 21,4

2 I 5-10 5,0 5,0 8,0 4,0 0,9 11,9 2,7 2, 7 3,8 1,0 2,5 2,5 2 II 50-60 6,5 2,4 5,6 1,6 3,2 1.0 2,0 14,0 4,0 4,0 3,0 1,0 1.0 1,2 1,2 21,5 1,2 9,2 16,1 12,6 2 III 70-80 2,7 6,3 1,8 2,7 3,6 0,6 3,3 7,5 4,4 6,6 2,2 2,7 2,7 1,1 2,3 27,9 1,1 22,2 9,0 22,4

3 I 20-25 2,0 2,0 5,0 3,0 3,0 6,0 1,0 12,0 9,0 9.0 4,0 1,0 1,4 5,6 3 II 80-90 3,0 3,0 3,0 3,0 29,0 9,6 6,4 tr 1.6 1,8 1,6 3 III 160-170 4,0 6,0 1,0 ,1,0 9,0 17,0 9,0 2,0 1.0 2,0 7,0 5,0 1,0

4 I 25-35 4,0 9,0 14,0 18,0 20,0 11,0 1,5 0,7 0,7

Note: The different crystal forms are given in fig. 13. The denticular types 7 and 8 of anhydrite are abundant in profile 30 (Gypsum province). gypsum can still be strongly corroded although slightly corroded types dominate. Fragmental types indicate sedimentation processes and occur in the topsoil or near the contact of soil layers of different origin, as is the case with sample 2 in. Profiles 2 and 30 are merging at respectively 65 cm and 35 cm in aeolic gypsum layers. Near this contact oolitic types of gypsum are abundant as a result of wind action. However, there are occurences in which the oolitic nature of gypsum is not related to wind action. In profile 1 there is an accumulation of pedogenetic gypsum in the deeper subsoil. Oolitic types are abundant, but can come into being easily by a slight attack of water if the euhedral type lb was the dominant product of crystallisation. If the edges are dissolved the material will be converted in the oolitic type 7.

.Summarizing it can be stated that there is weathering of minerals in the topsoil which is low in the subsoil. Slightly corroded material occurs throughout the profile, this being often due to a slight weathering during sedimentation processes. Gypsum is attacked more by the soil solution and even can be corroded in the deeper subsoil.

Table 19. Weatherability of minerals.

Heavy minerals weatherability light minerals weatherability

garnett low quartz very low spinel low chalcedony low zoisite+ low basic volcanic glass+" medium clinozoisitet medium orthoclase low epidote+ low albite" low hypersthene+ medium oligoclase+" medium diopside+ low andesine+" high augitet medium labradorite+" high pigeonite+ medium bytownite+" very high hornblende+" medium anorthite+ very high oxyhornblendet" low muscovite" low olivine very high nepheline" high anhydrite+ soluble gypsum+ soluble calcite+ soluble

77 G V T-B-E ^. Unstable, highly weatherable minerals

Moderately stable minerals

Stable minerais

G = Gypsum soil 60 - 100 cm V = Lapilli soil 60 - 100 cm T-B-E = Terrace-Balikh-Euphrates soil 0 - 100 cm

Fig. 15. Stability of the mineral content of soil in the fraction 50 - 500 p,

Between the various mineral provinces, there is a great difference in weatherability of the soil building material (see fig. 15). Deep gypsum soil has the highest degree of weatherability with 94% highly weatherable material. Volcano soil is less weatherable with 14% stable material, while Terrace-, Balikh and Euphrates soils have about 66% stable material, the rest being mainly moderately stable.

Owing to the mixed quartz content the maturity index can be given according to Pettijohn (1957) by the ratio ;quartz+chalcedony /feldspar. The ratio diopside/augite appeared to be highly variable in soil . So did the ratio epidote/clinozoisite in the Balikh region, due to the young alluvial environment. The ratio epidote/clinozoisite is low in the Euphrates soils, due to their high content of clinozoisite. The ratio quartz+chalcedony/feldspar is in Balikh soils about 1, but in Ter- race loam soils about lg, pointing to a more advanced stage of weathering of these soils.

8. CONCLUSIONS

The mineral provinces can be used as a basis for pedological classification, each province giving a unity in mineral composition and age. The topsoils and upper subsoils have been enriched by wind blown materi-

78 al, resulting in a certain discontinuity in the soil profile. Below this topsoil and upper subsoil the mineral assemblage is rather homogenic.

The content of olivine is decreasing with distance from the Volcano province, however there is also a supply from the north as is shown by the olivine- bearing Balikh sediment.

The easy weatherable minerals olivine, calcite, anhydrite and gypsum are common constituents of these soils. The observed weathering of gypsum and olivine point to a slight chemical weathering under present soil forming conditions. The terrace loam soils are more weathered than the younger alluvial of Balikh and Euphrates.

B. MINERALOGICAL ANALYSES OF THE CLAY FRACTION (<2 p.).

1. METHOD OF ANALYSES

After pretreatment with sodiumacetate pH 5, 30% hydrogen Superoxide and 2 N hydrochloric acid the soil material .$ 50 iiwas dispersed with sodiumpyrophosphate. The clay was collected by décantation of the suspension according to the Stokes law. The collected material was dried at 100°C and subsequently ground. The following specimens were prepared for X-ray diffraction measurements : a. Powder, orientated at random. b. Mg-saturated and glycolated, orientation 001. c. K-saturated and glycolated, orientation 001, heated up to 300°C and 500°C respectively. If there was not enough material for preparing powder specimens, the material was equally spread on a glass slide with the aid of aceton.

Equipment used for X-ray diffraction analysis: Philips stabilized generator PW 1310 with the wide-angle goniometer PW 1050 and Philips measurement equipment. Experimental conditions: X-ray tube Co, radiation Co KB, filter Fc; high tension 35 kV, current 30 mA;

79 divergence slit 1°, receiving, slit 0, lmm, scatter slit 0,5°: detector proportional counter. HV (PW 4025) detector 1620 V; discriminator (PW 4280) LL 280, window 190, attenuation 23; ratemeter (PW 1362) range 200, time constant 4; scanning speed 1° per minute; chart speed 600 mm per hour; Bragg angle (2 9) 2°-45 .

Quantitative determination by X-ray diffraction: Determination of clay minerals was done according to the 2 d values given by (Brown 1961) A number of standards with different weight ratios of certain clay minerals were compared. The intensity of characteristic reflections were measured in order tot construct intensity-mineral percentage graphs, (see fig. 16).

IP IK

Fig. 16. Intensity-mineral percentage graph of ratio palygorskite/kaolite. I /I = Intensity palygorskite 10,4 A reflection in cms/intensity kaolite 7,15 A reflection in cms. %P/%K = Ratio weighted percentage palygorskite/weighted percentage kaolite.

Short description of method: a. Measurement of intensities of characteristic reflections in cms. b. Calculation of ratios of intensities comparable with those of the intensity- mineral percentage graphs. c. Reading of ratios of percentages from the intensity-mineral percentage graphs. d. Calculation of percentage of minerals expressed in one mineral from the different percentage ratios e.g. ratios P/K,K/Mo,I/K etc. can be expressed as %P=x. %K etc. (for abbreviations; see below).

80 e. Multiplying x. %K by 100/total K gives the percentages of the different components . Problems encountered in the quantitative determination are discussed below. Chlorite and montmorillonite giving many reflections between 10-15 A were determined bij measuring the total peak area of these reflections. The total area was compared with the kaolinite reflection and expressed in cms intensity. The samples were heated up to 300 C and 500 C respectively in order to get an idea about the content of these two minerals separately. The palygorskite* 10,4 A and illite 10,1 A reflections are usually not to be separated due to the weak intensity of the illite line. Measurement of palygorskite and illite was consequently only possible on the weak 5,4 A and 4,96 A reflections respectively. Examination of pure palygorskite and illite showed that the intensity ratios P 10,4/P 5,4 and illite 10, l/illite 4, 96 were respectively 10 and 4. Therefore the intensities of palygorskite and illite could be calculated from the 5,4 A and 4, 96 A reflections and checked by the total intensity of the 10,4 A reflection. The result was reasonably accurate.

The choice of a place for measurement of intensity does not appear to be simple. Examination of pure samples and mixtures of these is necessary to obtain data of the influence of different minerals on the intensity of reflection.

The content of clay minerals has been indicated by the notation: no notation 0-10% + 10 - 30% ++ 30 - 50% +++ 50 - 70% Quartz and feldspar occurred in subordinate amounts and were indicated also. The symbols used in the tables for indication of minerals of the clay fraction are as follows: Mo=montmorillonite+mixed layer illite-montmorillonite, Chl=chlorite, P=palygorskite, I=illite, K=kaolinite, Q=quartz and F=feldspar.

2. MINERALOGICAL COMPOSITION OF THE CLAY FRACTION

The same regions as determined by heavy mineral research of the sand fraction 50-500 \i were examined for the clay fraction.

* Ssaftchenkov (1862; quoted by Milner 1962) first used the name palygorskite after the name of a mining district in the Urals. Milner prefers to use this name more than attapulgite given by de Lap- parent in 1935, who thought these were different from them. 81 The clay mineral composition of the different regions is fairly uniform due to the mixing influence of the brown loams of the Terrace region. Illite is the dominant mineral, followed by palygorskite and there are low amounts of montmorillonite, chlorite and kaolinite. The gypsiferous material has no components that give rise to new types of clays. In these deposits there is an admixture of the same clay mineral assemblage as that of the brown loams.

Table 20. Clay mineral composition of the different regions.

soil region sample depth clay minerals nr in cm

Balikh 37 II 21 Mo Chl+ K Q F IV 70 Mo Chi P++ + K+ 0 F 15 I 6 Mo Chi P I+++ K 0 F IV 95 Mo Chi P+ 1++ K+ Q F Euphrates 20 II 32 Mo+ *CM* P 1+ K+ 0 F IV 88 Mo+'fChl+ P 1+ K Q F Gypsum 30 III 25 Mo Chi P+ 1++ K 0 F VI 85 Chi P++ 1++ K Q F + H Raqqa Terr. 24 II 12 Mo Chi P + K+ Q ',F IV 75 Mo Chi P++ ]Z K 0 F Harnret Terr. 5 II 20 Mo+ Chi P +++K+ Q F IV 80 Mo Chi P 1+++K+ Q F Trans. Terr.-Vole. 31 I 2 Mo+ Chi P+ * K+ 0 F V 82 Mo Chi P+ ++ K Q F Volcano 16 I 2 Mo+ CM P K+ Q F III 65 Mo+ Chi P+ ++ K+ 0 F

The Euphrates region has a clay mineral assemblage typically different of that of the brown loams, having a higher content of montmorillonite and chlorite and consequently a lower content of illite and palygorskite. As for new formation of clay minerals after deposition it appears that the content of montmorillonite has increased in the topsoil, owing to a thorough wetting of the upper 30 cm after winter rains. It will have been formed at the cost of palygorskite.The percentage of illite in soils of the Balikh region is higher in the upper than in the lower part of soil. It seems likely that new formation of this mineral took place. The chemical conditions necessary for these new formations are fulfilled by the chemical characteristics of the soil profile. Higher pH-values, being typical for arid regions, together with higher

82 concentrations of magnesium and calcium will led to the formation of mont- morillonites. If beside calcium ions also potassium ions are abundant illites will be formed.

The mineral provinces determined by heavy mineral research generally have a similar clay mineral assemblage. Only the Euphrates Province has a different assemblage as compared with the other regions. This is caused by the hardly advanced stage of weathering of the soil profiles under prevailing arid climatic conditions and in some cases by the nature of the parent material.

C. MINERALOGICAL ANALYSES OF THE SILT FRACTION.

A study of the silt fraction together with that of clay and sand fraction is necessary to get information about the distribution of minerals over the different fractions. The silt fraction was examined by X-ray diffraction; determination according to the X-ray powder data file (1962).

The results are given in table 21. The mineralogical composition of the clay and sand fraction is indicated too. Description of mineralogical composition of the silt fraction in the different regions is given below. Hamret Terrace, Raqqa Terrace and Balikh region. The fine silt fraction 5-10 p. has a high content of clay minerals while the medium silt fraction 20-30 ^ is rich in micas. Montmorillonite and chlorite occur in the medium silt fraction. The sand fraction is composed mainly of quartz and feldspar, the amount of which is gradually decreasing into the finer fractions. Euphrates region. The silt fraction has a relatively high content of chlorite. Mica is abundant in the sand fraction. Volcano region. Chlorite, montmorillonite and kaolinite occur in the fine-medium silt fractions. The augite content is relatively high in the fine sand and coarse silt fractions. Olivine is the most abundant mineral of the sand fraction.

83 Table 21. Mineralogical composition of clay, silt and sand fraction.

Sample Sample Region Mineralogical composition of clay, silt and sand fraction. nr depth in cm <2p, 5-10 p, 20-30 |i 50-500 p,

5 I 0-8 Hamret Mo+ Chl P I+++ K+ Q F Mo Chl P I+++ K Q+ F Mo M+++ K Q+ F 5 II 15-25 terrace Mo+ Chl P I+++ K+ Q F Mo Chl P I++ K Q+ F Mo M+++K Q+F+ +++ + + + 5 III 40-50 Mo Chl I K Q F Mo Chl I* *K Q F Mo M++JK Q+F 5 IV 75-85 Mo Chl I+++K+Q F Mo Chl I+++K Q F Mo M+++ K Q F ++ ++ 15 I 0-12 Balikh Mo Chl P I+++ K Qx F Mo Chl+ P+ 1++ K+ Q F Mo Chl M+++ K Q F Q F g e + +++ + + + ++ + +++ + 15 II 15-25 Mo Chl P I K Q F Mo Chl P I K O F Mo Chl M K Q F Q.. F g <= + + ++ + 15 III 40-50 Mo Chl P* I++ K+ Q F Mo Chl P I K Q F Mo Chl M++ K Q+ F+ Q F++ g e 15 IV 90-100 Mo Chl P+ I++ K+ Q F Mo Chl+ P+ I++ K+ O F Mo Chl M+++ K Q+ F+ Q F e

Sample Sample Region <2H 2-50 H. 10-50 p. 50-500 p, nr depth in cm

+ ++ + + Q F e a h 24 HI 15-43 Raqqa Mo Chl P I K Q F Chl I M K Q F ++ ++ + + + Z I 24 IV 71-79 terrace Mo Chl P I K Q F Chl + PI K Q F ++ ++ + + + ++ Q F e a h 20 II 30-35 Euphrates Mo Chl I K Q F Chl M KOF + + + Q F M e a h 85-90 Mo++ Chl+P I+ K Q F Chl++ M K Q F+ 20 IV Q++ F+ M+ e a h + + ++ 161 0-4 Volcano Mo+ Chl P I++ K+ Q F Chl M K Q F+ a+ Qv F e a h o

Abbreviations: Mo =Montmorillonite Q =Quartz g =garnet Chl=Chlorite F ^Feldspar e =epidote+clinozoisite P =Palygorskite a =augite+diopside I =Illite h =hornblende K =Kaolonite o =olivine M =Mica v =volcanic glass Gypsum region. Fresh material was examined by a microscope. The silt fraction contained gypsum and calcite. About 10% of the fraction smaller than 50 M. consisted of clay <2|i.

D. MINERALOGICAL ANALYSES OF SOURCE ROCKS FOR THE SOIL MIN- ERALS.

The state of weathering from soil minerals can only be estimated if the history of the soil building materials is fully understood.

1. ORIGIN OF THE BROWN LOAM

Tertiairy limestones and marls were treated with 1 N-HC1 until, all lime was dissolved. The residue smaller, than 50 p. was examined by X-ray diffraction. The residue larger than 50 M- was examined by a microscope and some samples were separated in a heavy and light sand fraction. The results are given in tables 22 and 23.

Table 22. Mineralogical composition of the residue <50 p, from Tertiairy marls and limestones.

Sample lithology geological <50n >50p. mineralogica: composition number age weighted weighted residue < 50 p, 7oof %of total total rock rock VII ' m. Lst Pliocene 9,4 0,2 Chi P" 1 K Q F I cl. marl Miocene 65,0 0,4 Mo P+ 1+++ K Q F + ++ IV Lst Miocene 3,8 0,04 Chl PIf] K Q F V Lst Miocene 3,9 0,2 Chi P 1 K Q* F ++ + VIII marl-Lst Miocene 16,1 0,4 P K Q F • + +++ IXX m. Lst Miocene 5,8 2,8 Mo P K Q F XXII m. Lst Miocene 14,3 0,03 Chi P++ ** K QIF XXIII Lst Miocene 3,8 0,0 Chi P++ ++ K F ++ ++ XXV Lst Miocene 2,6 • 0,02 Chi P K Q F XXVI Lst Miocene 4,3 0,2 Mo P** ++ K Q+ F VI marl-Lst Oligocène 22,4 0,2 P+ ++ K Q F XXVII marl-Lst Oligocène 22,6 0,1 P** F + ++ K" II marl-Lst Eocene n. m. n.m. Mo* P °-Q+ F I++I + HI Lst Eocene 2,3 2,8 Chi P++ K Q F XX chalk Eocene 5,6 1,4 P++ Q"1"b +++ XXI Lst Eocene 4,0 0,1 p r K Q F Abbreviations: m=marly, cl=clayey; Lst=limestone.

85 Table 23. Heavy minerals of the Tertiairy residue and of brown loam near Tuwal al Aba.

Sample Transparent heavy minerals in mutual percentages

n nr. depth % light % heavy 1 in min. min. •

Tourmalin e Brookit e Hypersthen e Opaqu e Zirco n Garne t Spine l Kyanit e Zoisit e Epidot e Alterit e Saussurit e Rutil e Brow n hornb l Accessorie s Muscovit e Chloritoi d Clinozoisit e Clinopyroxe n Ox y -hornble i Glaucophan e

I Staurolit e 1 Titano-augi t | Gree n hornb l 3 Tuwal al Aba 35 I 0-10 0,5 0,05 36 tr tr 7 1 2 8 17 22 1 9 2 12 5 1 6 5 2 36 I 0-10 1,6 0,1 33 3 1 6 tr 2 6 21 24 9 1 8 5 1 1 7 3 1 1 36 II 30-40 0,8 0,1 37 4 tr 2 2 tr 1 4 24 28 1 10 1 11 4 1 4 1 1 1

% light % heavy min. of min. of Nr age total total and residue residue lithology

VII Pliocene m. Lst 1,4 0.1 54 1 8 1 1 1 5 19 30 8 7 1 12 6 I Miocene cl. marl 0,1 0,001 28 4 16 6 1 6 24 16 4 1 4 3 15 IXX Miocene m. Lst 28,9 0,04 68 24 7 4 9 25 3 1 3 8 5 2 7 2 XXVI Miocene Lst 24,3 0,1 42 7 9 1 7 19 11 2 7 1 16 1 4 7 1 7 III Eocene Lst 0,1 69 24 8 44,0 3 12 20 3 1 1 6 6 4 9 4

For abbreviations one is referred to table 22. There is a striking resemblance between the mineralogical composition of the Tertiairy residues as compared with the brown loams of the Balikh Basin (Terrace-Balikh province), as described in section B and A of this chapter. Palygorskite and illite are the dominant minerals of the clay fraction in the Tertiairy residue as well as in the loams of the Balikh Basin. The Tertiairy residue has a heavy mineral assemblage (table 23) which taken as a whole, is quite similar to that of the brown loams, having a high content of garnet, clinozoisite, epidote, hornblende and pyroxene. The content of zircon and rutile is higher in the Tertiairy residue than in the loam. Olivine was found in sample V. The most abundant minerals of the light fraction are quartz, chalcedony, feldspar and muscovite. The evidence obtained by comparison of the mineralogical composition makes it likely that the Tertiairy marls and limestone served as parent material for the Holocene loam cover. Weathering of these Tertiairy sediments took place most probably in Pleistocene times. Lime largely was dissolved and transported by the Euphrates and tributaries to the sea leaving behind a residue, of which in the course of time the sand/clay ratio increased due to some transport of clay by fluviatile action. During the semiarid climate in Post-Pleistocene times aeolic action started to have a minor influence on sedimentation processes. The result of the increased wind action was a rather uniform thin cover of loam on the Pleistocene- Tertiairy substrata; uniformity as for the homogenic mineral assemblage due to the high sorting effect of wind action and the thickness of the deposit. The content of alterite and saussurite in the Tertiairy residue is about the same as that of the loam. Clinozoisite and epidote are in a rather weathered condition. The quartz and feldspar grains have an angular appearance and are slightly etched. The content of opaque minerals is rather high in the Tertiairy residues. Since the appearance of minerals in the parent material is nearly similar to that of the minerals after deposition, it may be concluded that weathering was low after deposition.

The loam cover has the same mineral assemblage over great distances, as is proved by analyses of some samples near Tuwal al Aba (NW of the Balikh Basin). Analyses of the heavy minerals are given in table 23.

87 The statements made about origin of the loam cover will be applicable to a great part of Syria.

2. ORIGIN OF CLAY IN THE GYPSUM DEPOSITS

The gypsum deposits east of the Balikh have in the deeper subsoil an admixture of clay occuring as: a. thick layers impregnated with gypsum b. horizons with clay balls c. horizons with small clay blocks Some clay balls were examined by X-ray diffraction and compared with Pliocene clay. The results are given in table 24.

Table 24. Mineralogical composition of colluvial clay in gypsum deposits and Pliocene clay.

Sample Lithology age mineralogical composition nr IXXX Coll . clay Pleistocene Chi P+ I + 0 F C+ G XXX COU. clay Pleistocene Chi P1 i 'K Q F C G XXXI Coll . clay Pleistocene Chl++ P M' 0 F c' XXXII clay Pliocene Chl+ P I Q F c G A XXVIII clay Pliocene Chl+ P I ' 0 F c G' A'

Note: no pretreatments Abbreviations: G=gypsum; C=calcite; A=ankerite(dolomitic); Coll=colluvial.

The minerai assemblage of the clay from the aeolic gypsum deposit is rather similar to that of the Pliocene clay. Most probably the Pliocene clay was eroded in Pleistocene times and deposited on the sandy Miocene erosion products. However, the proluvial clay could also have originated from clayey layers of the Miocene. In Post-Pleistocence times the proluvial gypsum sand was redeposited several times by wind action. Therefore clay accumulations were only found in the deeper subsoil, the upper part of soil being purely aeolic. The accumulation of clay balls can be the result from a short transport of clay eroded from higher situated clay layers. The same holds for the occurrence of clay blocks.

3. MINERALOGICAL COMPOSITION OF THE HOLOCENE BASALT Basalt of the volcano Mankhar Gharbi was examined by X-ray diffraction 88 and microscope and constisted of volcanic glass, augite, forsterite and nepheline. The lapilli can be cemented by lime and gypsum or are not cemented. They are built up by volcanic glass, forsterite, augite, magnetite, nepheline and leucite. The volcanic glass is opaque due to inclusions of augite and olivine microlites. Without inclusions it generally has a brown or light greenish colour. Nepheline was found in the sand fraction 50-500 ^ only in subordinate amounts but lapilli grains contain about ten percent of this mineral.

E. SUMMARY.

Brown loam with a thickness of a few meters or more was encountered in the Terrace-Balikh region. A loam cover was found in topsoils of Volcano and Gypsum provinces but was lacking on top of the young alluvial of the Euphrates. The average heavy mineral composition of the four main provinces is given in table 25. The subsoil is taken for this purpose because of its intermediate composition in having often aeolic supply of loam in the original material. The sand fraction of brown loam is rich in quartz and feldspar while olivine and volcanic glass are the main components of sand from the Volcano province. Gypsum sand is composed for more than 90 percent of gypsum. The average mineralogical composition of the clay fraction is Mo, Chi, p+, l++, Q, F, except for the Euphrates province being Mo , Chi, P, I , Q F (for notations see section B, 1). The fine silt fraction was found to be rich in clay minerals. The course silt fraction was found to have a composition comparable with the sand fraction except for the Volcano province where augite was more abundant in the silt fraction than in the sand fraction. Tertiairy sediments have served as parent materials for the brown loams which can be regarded as their insoluble residue. The proluvial gypsum deposits are characterized by the occurence of clay which minéralogie ally resembles Pliocene and Miocene clay. In the fine earth of lapilli loam soils, nepheline is occuring only in subordinate amounts, but it is a common constituent of coarse lapilli.

89 Table 25a. Average heavy mineral composition of the subsoil from the main mineral provinces.

Transparent heavy minerals in mutual percentages

in uri t

REGION Alterite+saus s Anhydrit e Epidot e Othe r miner a Amphibol e Olivin e Pyroxen e Zoisit e Opaqu e Garne t Clinozoisit e

Euphrates province 9 3 5 20 13 23 26 1 1 8 Terrace-Balikh province 36 6 3 18 27 13 13 3 12 5 Volcano province 26 1 6 7 14 8 57 7 Gypsum province 50 6 2 8 13 7 9 3 31 9 12

90 CHAPTER IV

SEDIMENTOLOGY OF THE SOIL MATERIAL

Holocene deposits given in chapter in, A, 2 are discussed below. Sedimentology of the soil material should be examined thoroughly before interpreting the soil -forming process. Therefore, sedimentological characteristics of the main soil-forming materials are discussed and deductions are made about their origin and way of deposition. For location of the deposits one is referred to the soil map and fig. 11.

1. SEDIMENTOLOGY OF THE BROWN LOAM COVERING THE PLATEAUS

The brown loam of the Balikh Basin was derived from Tertiairy strata as is shown by comparison of the mineralogical composition of the Tertiairy residue with that of the brown loam (see chapter HI, D, 1). There are two different types of brown loamy sediments, namely the alluvial fill of the Balikh valley and the aeolic loamy cover of the plateaus. The latter will be discussed below. The maximum thickness of the loam deposits on the Pleistocene terraces is 270 cm, while the deposit is lacking at the Holocene Euphrates terrace. Often there is an admixture of gravel derived from outcropping terrace gravel. Layered material was not found, but this can easily have been destroyed by soil fauna since conditions were aerobic for a long time (see chapter I, A, 10). The texture of the soil profile is quite homogenic in having a clay content 91 of 30-35 percent. Cementation of clay particles due to weathering in the upper part of soil can be regarded as an important agent enabling transport of clay- rich material by wind action. A cementation into clusters of palygorskite in material of the topsoil has been observed (chapter VIII, A, 2). The time of deposition of these loams will have been during and after the first stage of formation of the Mankhar volcanoes for the following reasons: —the top layers of the lapilli deposit are intensively mixed with loam; —incision of lapilli deposits took place and the valleys formed are often filled up with several meters of loam which frequently are mixed with lapilli; —the lapilli-built piles in the crater have an aeolic admixture of loam; these piles have more recently been formed in a later stage of development when the climate was more arid. The first stage of the Mankhar- volcanoes was an explosive one with pyroclastic products and has been dated to be after the formation of the Upper Pleis- tocene terrace and before the formation of the Holocene terrace. For reasons discussed above the loam will have been deposited on the terrace at the end of the Upper Pleistocene and in Holocene times. During pluvial times there will have been a quite luxurious vegetation and consequently an intensive weathering. The formation of a calcareous soil took place during the last pluvial. The climate became more arid at the end of the Upper Pleistocene which led to destroying of the natural vegetation (phase of Rhexistasy, Erhart 1956). There was an intensive erosion due to the action of winter rains and during the dry summer of wind. The terrace "Island" (see chapter H, B) became isolated at the end of the Upper Pleistocene and is covered locally by more than 200 cm loam. The material will have been deposited by aeolic action since the "Island" had no supply of drainage water from the north. Therefore, the loams on the Hamret terraces can be regarded as aeolic deposits too, although there was possibly a greater supply of fluviatile material.

The climatic conditions during the Holocene had much influence on sedimentation processes. For a description of the Holocene climate one is referred to chapter I, A, 10. The arid Preboreal and Boreal with dominant wind action were succeeded by the moister Atlantic period in which run off processes were abundant which are responsible for the higher content of gravel in the deeper subsoil. The topsoil contains a larger amount of grains smaller than 200 [j, as com- 92 pared with the deeper subsoil what may be due to the intensive aeolic action in the arid Subboreal and Subatlantic.

2. SEDIMENTOLOGY OF THE SANDY GYPSUM DEPOSITS

A large part of the region is covered by a sandy gypsum deposit with a thickness of three to eight meters. Locally clay deposits of several meters thick are intercalated or there is an admixture in the deeper subsoil of clay balls and/or small clay blocks. A repetition of clay horizons at a distance of four to five meters from each other was observed at some places. The clay might have originated from Pliocene and Miocene clay deposits. Loamy material can be mixed with gypsum in the subsoil when an aeolic loam cover is present on top of the soil profile. The hypothesis that such deposits are the weathering products of lagunaire gypsum in situ will not hold for the following reasons. The Miocene gypsum was deposited in a lacustrine facies on a sea bottom with irregular topography. Submarine depressions between marls, limestones and sandstones were filled up with gypsum and consequently these deposits are not extensive. This is in contrast with the sandy gypsum deposits of the region which cover without interruption a vaste area. These deposits are overlain by Lower Pleistocene gravels and therefore are older. Deposition will have found place at the start of the Quarternary and must be related to the rising of the Tuwal al Aba anticline with Miocene gypsum deposits which upon weathering gave rise to a supply of angular gypsum grains. A mantle of gypsum debris was found to surround the anticlinal uplifts. The occurrence of clay layers, clay balls or small blocks are indicative of temporarily wet conditions during transport. However, for gypsum, wind action may have been an important transporting agent. The deposit is considered to be proluvial because it is lying near to his source region. During the Pleistocene this sandy gypsum deposit was dissected intensively and some gypsum sand was transported to the lower lying terraces. The upper 60 cm of soil are generally free of clay due to aeolic action on this surface layer during arid periods of the Pleistocene and Holocene. Gypsi- ferous deposits have been protected against such erosion by the formation of a crust. 93 3. SEDIMENTOLOGICAL CHARACTERISTICS OF THE OTHER SOIL MATERIALS

The Balikh alluvial is built up of brown loams and clays originating from the Tertiairy residue (chapter m, D). Locally a platy fabric was observed derived from fluviatile action. The Euphrates alluvial is built up of sediments with varying texture and a platy fabric is often present. Irrigation water loaded with sediment particles has locally led to deposition of a loamy to clayey top layer of several centimeters . The lapilli has an admixture of about 25 percent of grains larger than 2 mm. Generally these have a size of 2-4 mm, but 4-8 mm does occur also.

4. SOME OBSERVATIONS ABOUT SEDIMENTATION DURING AND AFTER A SAND-DUST STORM

A storm started during the night, became very intensive at about nine hours in the morning (11-12-1965); direction of wind from east to west. Some samples were collected in the Gypsum and Hamret region. The samples 48 and 49 were taken during the storm near the village of Mai'zile and 50 after the storm near Hamret Butiya; 48 was collected with a disc of 40 cm diameter placed vertically above the soil surface; 49 and 50 were taken in small depressions . With the disc 500 grams of soil were collected in only one hour. Small wind ripple marks were present in the just deposited material in depressions.

Table 25. Texture data of aeolic material accumulated during and immediately after a dust-storm.

Region sample texture % ) % 1 no >50 M- 50-20u <2\i. C CaCO3 Gypsum

Gypsum 48 87, 1 2,6 10, 3 0,36 28, 5 6,46 49 92, 6 5,4 2, 0 - 22, 5 1,42 Hamret terrace 50 73, 7 25,3 1, 0 0,50 23, 7 tr

The data of table 25 show that an admixture of 10% clay in the aeolic material is possible. This will be due to cementation of the clay particles and rounding of these aggregates. The percentage of carbon points to a large contribution of topsoil material. In the Gypsum region the percentage of gypsum is relatively low, due to the angularity of the gypsum grains and the mantle of aeolic loam covering the

94 gypsum deposits.

The occurrence of dust-storms as related to climate is discussed in section A, 6 of chapter I.

95 CHAPTER V

FLORA AND FAUNA

Flora and fauna in relation to climate, soil and topography are discussed below. The different plant species found in the Euphrates-Balikh region are presented in table 26 and the location of the sample areas in fig. 18. Plants took up silica from the soil as is proved by the occurrence of phytoliths. They are discussed in section A, 4.

A. Flora of the Euphrates-Balikh Basin.

The Euphrates-Balikh Basin belongs to the Irano-Turonian phytogeographic region. E.R. Guest (1966) considers the family of the Chenopodiaceae characteristic for the region. Certainother groups like Astragalus and Salvia are al- ways present.

1. EFFECT OF CLIMATE ON VEGETATION.

Climatic factors largely determine the general aspect of the vegetation. The climate of the Euphrates-Balikh Basin is characterised by dry, hot summers and relatively cool winters. January with a relatively high amount of rainfall has an average temperature of approximately 6°C. Therefore, rainfall of the winterperiod cannot be used optimaly by the vegetation because of the too low temperature. The main growing season is from March to April with some rainfall and more favourable temperatures. This short period in which growing of plants is possible gives rise to a semi-desert vegetation although the general aspect of

96 the climate is arid (see chapter [). If there is sufficient rainfall the desert can be converted at spring time from a grey-brown dead surface into a green grassland with numerous bulbs and poppies. During the long summer there is no surface water available and the intense heat and dryness of the air create conditions of extreme desiccation. The moisture content of soil drops far below wilting point (chapter I, B, 2). Ephemeral annuals are able to survive such unfavourable conditions. They rapidly complete their life cycle in spring time and then lie dormant in the form of seeds. Distribution of seed over very large areas is made possible by wind action, taking seeds with it in wind-blown clayey balls (Simons 1967). Most perennial plants are shrubs and occur at places where there is more moisture e.g. in depressions and wadis. Their roots draw in water from considerable depth and from a wide area round about. They are spaced meters apart owing to the small amount of water available. Their leaves often have spines and are rolled. Stem and branches are woody and tough andhave no water storage tissue. Some desert perennials obtain moisture from night dew but this effect will be very low in summer.

3*f'

Fig. 17. Semi-desert vegetation of the Balikh Basin.

97 Deserts, semi-deserts and steppes are distinguished from one another by differences in the physiognomy and the structure of their vegetation, that is, the different degree of coverage is the decisive factor. The semi-desert of the Euphrates-Balikh Basin may support cultivation in the period March-April and provides grazing in all seasons, though it is often bad grazing. A true desert is territory so devoid of vegetation that it cannot provide ap- preciable grazing and dry farming is not possible.

2. EFFECT OF SOIL AND TOPOGRAPHY ON VEGETATION.

The Tertiairy residual material (brown loam) is transported by fluviatile and aeolic action and covers most of the deposits, or is mixed with them, except for the Euphrates alluvial. Therefore, the influence of different lithology is mas- ked. The vegetation of the brown loam consists of a uniform shallow rooting grass cover, and locally shrubs are found. Plants have in common that they are calciphyles due to the highly calcareous soils with high pH. Even quite small amounts of salt in the soil may prohibit the occurrence of many plant species, for: a. it causes osmotic troubles for the plants; b. it forms often a relatively hard crust at the soil surface; c. it decreases the volume of pores in the soil. Saline soils occur in the Euphrates valley and locally in depressions of the Terrace and Volcano regions. Lapilli-containing soils of the Volcano region generally have an excess of exchangeable sodium and consequently have a poor structure. Gypsum soils occur over a wide area. For most plants growth will be reduced when the gypsum content is above 25 percent (Smith and Robertson 1962, Van Alphen 1968). For the greater part of the year there is a sharp contrast in colour between the greyish-brown plateau and the green Euphrates valley. Valleys on the plateau lands are generally filled with loam, have more moisture and therefore their own characteristic type of vegetation; bulbs are more commo. and they have more grass than their surroundings. I Perennial shrubs are numerous in the Balikh valley where soils have a 98 higher content of moisture. Trees occur in the Northern Balikh valley at Ain Arus and in the Euphra- tes valley where roots can reach the groundwater. Edaphic desert is found on highly saline soils and on flat impervious soils and rocks. Agricultural activity leaves the patches used,nearly bare. Wind erosion is quite severe during the summer at such places and microdunes are formed.

3. VEGETATION OF THE DIFFERENT REGIONS.

Plant species were collected in different regions according to their abun- dancy be it that some small areas were sampled as a whole. The plants were identified by Mrs. T. Baretta of the Institute for system- atic Botany at Utrecht (Netherlands) and are shown in table 26. Orders, families and species are arranged alphabetically. The number of plants taken will not be- sufficient for determining the different associations but a least they give an impression of what can be expected. The location of the sample areas is given in fig. 18. Only a few plant species were collected in the regions 5,8, 9 and 10. These are not indicated in table 26 but are given in the text. Theregionsl and 2, and the southern part of region 3 belong to the Euphrates, region (fig. 18). This region is characterized by a great number of weeds and halophylous plants due to irrigated culture. Halophylousplants like Suaeda bac- cata occur on the sides of irrigation channels and on saline agricultural patches. Many shrubs are found in the flood plain. The Balikh (eastern part of region 7) is cultivated and many shrubs are found (see table 26); ploughing prevents the development of a grass cover. Cephalaria syriaca (L.) Schrad (fam. Dipsaceae) was found in the northern Balikh region (8). Gramineae (or Poaleae) e.g. Koeleria phleoides are the most abundant plants of the plateau lands. The characteristics of the different plateau regions are given below. Region 4 and 5, and the western part of region 7 belong to the Gypsum region with shallow loam soils on gypsum sand. Valleys are generally filled with loam and the tops of hills are composed of nearly pure gypsum sand, often encrusted at the surface. The vegetation of gypsiferous soils is characterized by the occurrence of Achillea santolina, Launea spinosa and Ziziphora tenuior.

99 TABLE 26i PLAflTS 0? THE EUPHRATES-BALIKH BASIH •

PLAR son. PLABT BEOIC* PE0PEHTIE3 PBOPsrrn 1 3 f | tra a ordar faaily apaciaa 1 i 3 4 6 7 waa d ï Apialaa Apiaeaaa Buplaurua glauoua Hobill A Caat ax D.C. X X II Î Cauoalia taoalla Dal. X X Hippoaaxantbna boiaalari Baat. A Hauak.ax Boisa. X X Aataralaa Aatarao«** Achill»» saatollna L. X X X X z Artaalala barba-alba Aaao X X X Bvax «natolie* Bolaa. at Haldr. X Oundali» tournsfortil L. X X X Koslpinla llnawia Pali 1 X Lauasa apiaoa» (Porsk) Scb. bip. X X X X Laoatodoa arabloua Boiaa. X X Matrioaxi» auraa (Loafl) Sob. bip. X X Katrioaria ebaaoallla L. X X Saaaoio ooronopifolius Dsaf. X X X Braaaioalaa BrasBlaacea« Alyaaua aaaioooidaa Boiaa. 1 X X Arabldopaia puaila (Stapb.) Buacb. X 1 X Caps*11a buraa-pastoris (L.) Madik. X X s X Daseurainia aopbU (L. ) Prantl. X X X Dlplotaxla acria (rorsk.) Boiaa. X X X Dlplotaxla oruooidaa (Tornar) D.C. X X X X Lspidiua draba L. X X X X MalcolaU afrieana (L. ) B.Br. 1 X Maloolaia «raaaria D.C. X Maleolaia toruloaa (Dasf.) Boiaa. J X Moricandia nitana (Tiv.)>Dur. A Bart. X X X SiajBbrlua irio L. 1 X X Siayabriua scbiapari Boiaa. 1 X Slayabriua aaptulatus D.C. J X X Starigaostaau» sulpburaua (Banks A Solaadar) Borna. X X X Papavar**««* Hypaooua proouabana l>. X X X Basadaoasa Rassda lutaola L. X X X X Carjopbjllalas Caryophy1laoaaa Biantbua Bultipunetalua Sar. X X X Xiauartia picta (Slbtb at SaJ Borna. X X X X Silana coniflora Vaaa ax Ottb. X X X Spargula pantaadra L. X X Spargulari* diaadra (Ouaa) Haldr. •* Sart. X X Cbsnopodlacaas Salsola Till OM Dal. X X X Suaada baceata Fbraak. ax 3.V. Osai. X X X Clvt&laa Taaarioaoama Taaarix tatandra Ouabb* «x Bunga X X x X X Oaranialaa Oaraaiaeaa* Erodiua oiconiua (L.) L'Har. X X Erodlua oioutariua (L.) L'Har. X X X X Srodlua Bosoaatua (L.) L'fiar. X X LlliBl«B Irldaoaa* Croous spac. X X Llliaea«« Kusc«ria longicapa Boiaa. X X 1 Kusoaria ntcaaosua (L.) Mill. X X PlsJit*gln»l*s Plantaginaoaaa Plaatago notât* Lag. X X Plant*go ovata Forak. X X X Poalaa Poaoaaa Alopaourua Byoauroids» Buda. X X X X KoalarU pnlaoidaa (Till.) Para. X X X Polygonal*a Polygon»«aaa Polygonua «Ticular* L. X X Priaulalaa Priaulaeaaa Androaaoa r'Tlai L. X X X Bamiaeulalaa Banunoulaoaaa Adonis aaativmlia L. X Adonia autuanalia L. X X X Adoaia palaastin« Boisa. X X X Caratooapbsl« falcata (L.) Para. X X X Soaalaa fsbacaa« Albasl aaurorua Madik. X X X X Astragklus ruasallii Banks «t Solandar X X X lUdioago polyaorpha L. X X Onobrychu« orist*-gall1 (L.) Laa. X X Ornithopua ooaprsasua L. X X 7ioi* palasstin« Bol*»« X X Rutalaa Butaoaaa Haplophjllua buxbauaii (Polr.) Boiaa. X X Haplophyllua loagifoliua Bolaa. X X X Solanalaa Bor«glnaoa&« Arnsbi« dacunbana (Ta&t.) Coaa. «t Eral. E X X C onTolvulacaaa ConTolvulus piloMllifoliua Baar. X X Convolvulus Btaohjdifoliua Choisy X X Crass« oratie« L. X X X Laaiaoaaa S«lvi« pal«*atin* Baatb. X x X Salvia apinos« L. X X X Taucriua pollua vas albua (Mill.) Florl X X X Ziaipbora tanuior L. X Ox-obanohacsfta Ciataacba salaa (C.A.May) 0. Back X X Soropbular iaoaaa Taroaio« dldyma Tan. X Solanacasa Lyoiua arabieun Scbwainf. X X X X Thymlaaalsa Blsagnaesaa Sla«gnua auguatifolica L. X X Koracaaa Norua alba L. X X

100 Fig. 18. Location of the sample areas for vegetation survey in the Euphrates-Balikh Basin. Legend: 1. Western Euphrates region. 6. Tributary of Wadi al Fayd. 2. Eastern Euphrates region. 7. Balikh-Gypsum region. 3. Volcano-Euphrates region. 8. Northern Balikh region. 4. Gypsum region with terrace gravel. 9. Limestone region. 5. Gypsum region. 10. Tuwal al Aba region.

Colchium deserti-syriaci Feinbr. (fam. Liliaceae) was found in some loamy valleys of region 5. While the vegetation cover of the deeper loam soils on the Pleistocene terraces is continuous, this is not the case in the volcanic and gypsiferous areas due to soil deficiencies. Vegetation of volcanic lapilli soils is characterized by a more scanty appearance and microdunes have developed. Shrubs are more common and plants generally are more resistant to alkali. Some typical species are Ceratocephala falcata and Astragalus rusellii. Loamy valleys of the plateaulands (region 6) are relatively rich in plant species. Bulbous plants as Muscaria racemosum are common. Many plant species occuring in this valley are also found in the Euphrates valley with other en- vironmental conditions. Eminium spiculatum Blume Ktze (fam. Araceae) is abundant on shallow loam soils underlain by limestone (region 9).

101 Gagea chlorantha M.B. (fam..liliaceae) was encountered on gypsiferous soils near Tuwal al Aba (region 10).

4. THE OCCURRENCE OF PHYTOLITHS.

Plants take up silica and precipitate it at walls of cells or channels. The occurrence of small particles of opaline silica in soil derived from plants has long been recognized by Russian pedologists. In 1843 Ehrenberg introduced for these opaline particles the name phytolitaria (phytoliths), implying the stony part of the plant. Most of the phytoliths are found in the fine sand and silt fractions of soil.

The following method of analysis was used: The fraction 10-210 V of soil was brought into an alcohol-bromoform mixture with specific gravity of 2,2. Opal has a specific gravity of 2,1 (Milner 1962) and therefore will float on the liquid. The separation appears to be imperfect but the lighter fraction thus gained has a high content of phytoliths. This material and some plantrests were studied by a pétrographie al microscope. Many phytoliths were described by Grob (1896), Netolitzky (1929), Smithson (1958) and Parfenova, Yarilova (1962). These autors presented types formed in Gramineae (Poaleae) which show a good resemblance to those found in the region. The forms collected in soil material of the Balikh Basin are shown in fig. 19. Silica taken up with the soil solution is gradually filling the cells, starting at the cell wall and growing centripetally. Thus are formed casts of the long (a,b,c,f) and the short (d,g,h,i,) grass epidermis cells. The protoplasma is replaced by silica, but there are often bubble-like rests of it in the opaline bodies (d). The surface of the long cell casts is smooth (a) or undulating (c). Type e has a central channel and probably is a part of a silicified hair. Table 27 represents for the different regions the relative content of phytoliths which are mainly derived from Gramineae. Types d and g were abundant in the Euphrates soil and types a and e in the loamy terrace soil. The content of phytoliths is relatively high in the Euphrates soil and the topsoils of Volcano and Terrace region. Sample 5 IV probably marks a former A horizon. A low amount was found in gypsum soil and Balikh alluvial. Silica goes into solution at the high pH normal in desert soils if enough water is available. Therefore, owing to the low moisture content only subordinate

102 Fig. 19. Forms of pytoliths found in some soil profiles of the Balikh Basin. Legend: a = long cell cast, smooth surface; b = long cell cast, undulating on one side; c = long cell cast, undulating on both sides; d = short cell cast; e = hair cast; f = long cell cast with undulating sides and central channel; g = thick fan - shaped bodies; h = small dumbbels; i = small square and rounded rectangular bodies; j = rod-like body.

Table 27. The occurrence of phytoliths in some soil profiles of the Balikh Basin. relative Region sample nr depth in cm content of phytoliths

Gypsum region 30 I 0-5 30 II 8-13 30 III 20-30 Balikh region 15 I 0-12 15 II 15-25 15 III 40-50 15 IV 90-100 Euphrates region 20 II 30-35 20 III 60-65 Volcano region 16 1 0-4 16 II 20-30 16 III 60-70 Hamret terrace 5 II 15-25 5 III 40-50 region 5 IV 75-85

note: + relatively low ++ relatively abundant amounts of silica will be dissolved. However, during the short growing season, the soil moisture taken up by plants will contain some silica and phytoliths will be formed. Some aspects of the effect of phytoliths on the plant are discussed below. Details about this subject are given by Netolitzky (1929). The opaline incrustations lower the permeability of the cell wall for water and solutions with as a consequence a reduced evaporation. They protect the plant against eating by animals. Pointed leaves have been found often to be silicified at the ends. 103 Some authors (mentioned by Netolitzky) state that the formation of phytoliths is merely a phenomenon of nutritional supply and more or less an unfavourable factor for plant life. However, it cannot be doubted that their presence is favourable for the firmness of the plant.

B.Fauna of the Euphrates-Balikh Basin.

1 . VERTEBRATES.

Herds of sheep, goats and dromedaries move from one pasture to another and are indispensable for the food management from nomads and villagers. Animals must be able to withstand the extreme temperatures and absolute dryness of the summer. Dromedaries are highly specialized to withstand drought and can survive a waterloss of about one quarter of their total weight. Sheep store food reserve in their tails during winter and spring time and thus are able to live on dried grass during summer. Rodents are small and survive the hottest part of the day in burrows. Some of these are rabbits, hares, desert rats and porcupines. They obtain moisture from roots and stems they eat, and can thus go for long periods without drinking. Losses by evaporation and excretion are reduced to an extremely low level. Some desert rodents spend the hottest months in a state of inactivity. Foxes are quite numerous ; often they use karst pipes in the gypsum region as a shelter. Antilopes and wolves are seen occasionally. Reptiles, chiefly lizards (e.g. arual with a lenght of about 70 cm) and snakes are rather common. The variable blood temperature enables them to tolerate desert conditions rather better than warm blooded animals. A reptile is able to reduce its body temperature and the need for evaporation by burrowing into the ground or seeking shelter beneath rock, it also may obtain liquid from dew. The arual is active only in spring time and lies dormant for the rest of the year in burrows under the ground. The Euphrates river is rich in fishes. Tortoises, crabs and watersnakes were found in oxbowlakes of the Euphrates valley while frogs occurred in some desert pools. Birds are numerous in the desert at spring time but in summer they stay near rivers or move to more favourable territories. Partridges, pigeons, larks, storks, herons, falcons and owls were encountered.

104 2. SOIL FAUNA.

Insects and arachnida (spiders, scorpions, mites) being more abundant than earth worms in the desert, are well adapted to the unfavourable environ-, ment for they, -require little water, -can bear extreme temperatures, -lose little water by evaporation, -can bury themselves into the soil, -can spend very long periods in a state of inactivity. In the light fraction obtained with bromoform-alcohol (specific gravity 2, 2) also chitine rests of the external skelets of insects and arachnida were met. Round shell-like bodies with a brown to light brown colour (testaceans) occur in all profiles. They appeared in profiles 20, 16 and 5 in lower amounts, were more abundant in samples 30 I and n, and very abundant in profile 15. Al- so the variation of different chitinous skelets was greatest in the latter profile (the regions in which these profiles occur are given in table 27 ), this being due to the greater wetness of the Balikh valley. However, in soils of this valley crotovinas only locally were observed in contrast to the relatively great number of burrows in the drier terrace loam soils. Apparently the soil fauna influences soil structure more under dry than under wet conditions.

The chitine rests were examined by Mr. J.H. de Gunst (entomologist, ITBON, Arnhem, The Netherlands). The results are given below: Profile 15 of the Balikh region contains fragments and excrements of mites and testaceans; profile 20 of the Euphrates region contains mites (Acari ; Trombidiformes) and excrements of insectlarvae; profile 16 of the Volcano region contains fragments of mites and mandi- bles of insectlarvae. Mites, insects and protozoa were found to form the greater part of soil fauna. The population of bacteria and other micro-fauna will be approximately proportional to the amount of protozoa. Earthworms are intolerant of drought and frost (Rüssel 1950). However, wormcasts were observed in Balikh soil.

105 CHAPTER VI

LAND USE

1. HISTORY OF LAND USE

For details on the history of land use one is referred to Butzer (1961). The beginnings of agriculture during the Prehistoric period (6000-3000 B. C.) coincided with the most and warm Atlantic period (see chapter I, A, 10). The region under consideration was populated at that time, witness the 'tals in the Balikh valley. Flint sickles found on the Euphrates terraces and in the main valleys point to the cultivation of cereals. These stone objects have long been used, also when copper and bronze implements appeared. A beginning of irrigation has been dated to be between 4000 and 3000 B.C. The early historical desiccation shortly before 2000 B.C. was quite severe as conditions were temporarily more arid than at the present time. Towards the end of the last millenium B.C. (Hellenistic and Roman times) climatic conditions began to improve again and agriculture was the chief occu- pation throughout the Fertile Crescent. In Roman times very much land was under cultivation, supported by the construction of aqueducts and irrigation works, the rotation of crops and the apply of organic fertilizers. During the Byzantine period agricultural activity was greatly reduced owing to continued inflation and increase in taxation. Land deterioration became general in the early Arab and Crusader period (640-1250) followed by Mongol invasions at the end of the 13th century. Also the Turkish period (1516-1917) was not favourable for a good development of agriculture.

106 At the present day irrigation is practiced where possible supported by gov- ernment and private investments. Dry farming is a rather risky enterprise because of the irregular and scanty rainfall.

2. FARMING SYSTEM IN THE BALIKH BASIN

For this purpose the region is divided into: a. Valley lands of Euphrates and Balikh.

A monoculture of irrigated cotton (generally basin irrigation) is practised. There is a small hectarage of vegetables and irrigated cereals. The main source of irrigation water is the Euphrates. Water is pumped from wells at some places along the edge of the higher terraces. A crop rotation often practised in the Balikh valley in order to prevent dis- eases and to obtain a better harvest is cotton-fallow-wheat-fallow-cotton. A crop rotation of cotton and wheat in one year is impossible due to the long cotton season. The natural fertility of the soils is low. Therefore, nitrogen and phospho- rous must be supplied. b. Plateau lands .

A semi-nomadic sheep and goat husbandry is an important source of in- come. There is a limited hectarage of cotton and vegetables. Dry farming of cereals is practised extensively on the loamy terrace soil and in some broad valleys of the Gypsum and Volcano region.

107 CHAPTER VII

MAPPING METHODS

1. GENERAL MAPPING METHOD WITH AERIAL PHOTOGRAPHS

Vertical aerial photographs scale 1:8.000 were used and studied with a stereoscope. The aerial photographs were taken by E.I.R.A. (Florence, Italy) during the period september-november 1961 when soil conditions were slightly moist. After a study of relief features the different tone patterns were used to dis- tinguish expected soil boundaries. Very light grey shades on the aerial photographs were caused by: saline efflorescences at the surface; gypsum and marls at the surface; plants with a high albedo; sandy places in the Euphrates soil. There was a shade contrast of light grey and dark grey between: loam and gravel; non-irrigated and irrigated soil; ridges and sloughs of point bars. The lapilli deposits were characterised by a striated pattern derived from wind-formed mega-ripples. This striage is locally disturbed by diffuse run off patterns.

Soil boundaries were interpreted from the aerial photographs and trans- ferred to photomozaics scale 1:10.000. These photomozaics were used in the field and the expected soil boundaries were checked; where necessary the aerial

108 photographs were studied again. Augerings were made to a depth of lm and locally up to 3 m giving an evaluation of the following: — texture and colour of the soil material; — the approximate content of lime by the reaction on hydrochloric acid; — quantity of stones and gravel; — moisture conditions; — depth of blockage; — amount and kind of accumulations and concretions.

When the different soil types were established, pits were dug in the centre of the most characteristic soil bodies. From each soil pit a detailed soil description was given. Intake rate and occasionally soil temperature were measured and samples were taken in order to obtain data about chemical properties, permeability, soil moisture , field capacity and occasionally size of aggregates and aggregate stability. Soil maps were drawn on a scale 1:10.000 and reduced to 1:50. 000.

2. FIELD CLASSIFICATION SYMBOLS

During fieldwork it appeared to be necessary to express precisely and in short terms the properties of the soil in a symbol, this being useful not only to classify the soils in texture groups, but also according to depth, petrology, stoniness and diagnostic horizons. A similar system has been applied by many schools of pedologists. The system used by pedologists of the University of Utrecht (The Netherlands) was applicated to arid soils and is given below. Chemical consistence of the soil material is of definite importance for the properties of the soil profile. The following different petrological groups of soils were recognisable: (a) brown calcareous loamy and clayey soils; (b) grey marly soils ; (c) Euphrates alluvial soil; (d) sandy gypsum soils ; (e) light yellowish brown loamy lapilli soils and grey lapilli; (f) soils on gravel. For soils mentioned under a,c and f texture was sufficient to differentiate 109 them. However, for b it appeared sometimes to be necessary to differentiate between marl, marl powder and blocky marl (colluvial). In group d, geological gypsum with a gypsum content of about 50-70 percent, and proluvial gypsum with clay or marl blocks and a gypsum content of more than 25 percent were recognised. Group c was differentiated according to the content of silt or loam. A differentiation in A, B and C.soils was used, these having a depth of more than 60 cm, 30-60 cm and less than 30 cm respectively. The classification of depth is based on agriculture, 30 cm of soil being the minimum to have a successful crop of cereals and 60 cm of soil for a successful crop of cotton. The field classification symbol has four or more letters and figures; the first letter is an indication for the depth of soil, in the second place a figure for the stoniness, then the texture, and finally indications for the development of the soil profile. In the case of gypsum and marl soils, it was sufficient to use the indications of the petrology, such as Ag and Am (see below e). This system appeared to be very useful to work with and was a basis for constructing the soil map. The different notations together with some examples are given below: a. Depth of soil: A=more than 60 cm; B=30-60 cm; C=0-30 cm. b. Stoniness:0 =nothing; l=few; 2=medium; 3=rich; 4=very rich. c. Texture: S=sand; L=loam; Cl=clay lapilli soils—l=lapilli with particles > 2mm grade 3-4 (see b) Ll=silty lapilli with particles > 2 mm grade 2-3 lL=lapilli silt with particles > 2 mm grade 1-2 (l)L=loam with few lapilli and particles >2 mm grade 0-1 d. Development of the soil profile: b=lime spots; h=humus particles; r=mottling; v=vertic; cr=gypsum crust; c=gypsum pockets lower than 60 cm, Cpgypsum pockets between 30 cm and 60 cm, c =gypsum pockets in the upper 30 cm, the content of gypsum being lower than 25% ; A , B , C pedological accumu- P P p lated gypsum at depths of 60-100 cm, 30-60 cm and 0-30 cm respectively with a gypsum content of more than 25%; sa=salt accumulations lower than 60 cm, sa.=salt accumulations between 30 cm and 60 cm, sa =salt accumulations in the upper 30 cm. e. Petrology: Ag, Bg, Cg=geological gypsum with a gypsum content of 60-70 % or more at a depth of 60-100 cm, 30-60 cm and 0-30 cm respectively; Age, Bgc, Cgc=colluvial transported gypsum mixed with clay or marl blocks at depths of 60-100 cm, 30-60 cm and 0-30 cm respectively; Am, Bm, Cm= soils on marl; Amp, Bmp, Cmp=soils on marl powder; Amc, Bmc, Cmc= 110 soils on colluvial marl at depths of 60-100 cm, 30- 60 cm and 0-30 cm respectively.

Examples: AllLb=deep soil, more than 60 cm; stone content few; texture lapilli loam; lime accumulations. Ag0Lbc=deep soil, more than 60 cm; stone content nothing; texture loamy; lime, and gypsum accumulations lower than 60 cm; • lying over geological gypsum between 60 cm and 100 cm. C3L=shallow soil, less than 30 cm; stone content rich; texture of topsoil loamy; blockage on gravel.

Ill CHAPTER VIII

SOILS OF THE BALIKH BASIN

A review of methods of soil analyses is kept as brief as possible while problems met with texture analyses are discussed in more detail. Field description and analyses of the soil profile are given. Classification of the soils according to the "Soil classification , a comphre- hensive system, 7th approximation" (1960) with supplements (1964, 1967) will be dealt with. The micromorphology of the soil profile together with soil analyses are used as a basis for the evaluation of soil genesis. This subject is treated separately in chapter EX.

A. Description and analyses of the soil profile.

1. DESCRIPTION OF METHOD OF ANALYSES

Methods of soil analysis are described in detail by Jackson (1956). The analyses were carried out in the laboratory of the Royal Tropical In- stitute at Amsterdam and in the laboratories of the Soils Department and Ana- lytical Chemistry of the University of Utrecht. In addition to normal chemical analyses the following determinations were made in order to estimate soil salinity:

—the electrical conductivity of the saturation extract (ECe); —the electrical conductivity of the soil: water/l:5 extract (EC.) and determination of the different anions and cations in this extract; —the content of gypsum (% CaSO.).

112 The EC. was determined only if the EC,- was more than 0,5 mmhos. The EC of gypsum soils was much lower than could be expected from the ECg-values, gypsum being less soluble in the saturation extract. Gypsum was determined only in samples with a content of sulphate and calcium ions in the 1:5 water extract of more than 1 me/100 gr soil. Texture was determined without pretreatments to destroy organic matter, free iron oxides and carbonates. Thus determined texture figures give an approach to field-textures (as it is in situ). Some additional data and problems met with texture analyses are discussed in section 2.

Methods of mineralogical analysis of the clay fraction are discussed in section m, B,l. Total analyses of the clay fraction < 2 ß and fine earth smaller than 2mm were performed with Philips X-ray Fluorescence Apparatus (PW 1540, PW 1051, PW 1010); of selected samples also the silt fractions 5-10 |A and 20-30 p, were studied. The samples were fused with lithiumborate (soil: lithiumborate=l:5) into a glass. At the end of the fusion the melt was poured into an aluminium ring placed on a polished plate of graphite at 450°C. A copper weight was placed on the melt in order to from a glass button. A well-sized glass button weights 4,5-5 grams. The applied dilution with lithiumborate should not be more than ten times. For further details on X-ray fluorescence one is referred to Reynders (1964).

Micromorphology: Mammoth-sized thin sections of soil (15 x 8 cm large and 15 p, thick) have been prepared by the Laboratory of Micromorphology (The Dutch Soil Survey Institute, Wageningen, The Netherlands). This has been made with unsaturated polyester resin Vestopal-H. For further details one is referred to Jongerius.and Heintzberger (1962).

2. TEXTURE ANALYSES

Texture of soils was determined with different methods: A. Standard method with dispersion agents sodiumpyrophosphate Na.P„O . 10

H-O and sodium carbonate Na0CO„ without pretreatments to dissolve free 113 carbonates and without destroying organic matter. B. International method with pretreatments of 30% hydrogen Superoxide and 2N hydrochloric acid and in addition sodiumacetate buffer pH 5 added before.

Results of method A are given in fig. 20 and section 3 in percentages of oven-dry soil, containing free carbonates and those of method B in table 28 in percentages of the mineral soil without free carbonates. The percentages of clay and silt are often underestimated in method A. This may be due to the occurrence of pseudo-silt and pseudo-sand. These particles are not completely dispersed by the dispersion agents of methods A, but disperse after pretreatments with sodiumacetate and hydrochloric acid. Large differences in texture with different methods have been found in aeolic loams and soils of the Balikh region. The difference is smaller in soils of the Volcano region. The C. E. C. of topsoils from brown loams on the terraces is equal to or higher than that of the subsoil and much too high for the low clay and humus content. Therefore, the fine silt fraction can be expected to have a large content of clay minerals which is confirmed by minéralogie analyses (table 21). Apparently there is a cementation of clay minerals caused by carbonates, and by silica and alumina in the zone of weathering that is the topsoil (see Reyn- ders 1966). Palygorskite of topsoil samples has been found by electron microscopy to be cemented into clusters (analyses carried out by Wiersma 1966.)

Texture of gypsum soil was determined only by sieving methods. The results are shown in table 29 . The fraction smaller than 50 IJ. can not be subdivided in other fractions due to the influence of Ca ions which prevent the dispersion of clay.

114 100%

50-2000 M.

Fig. 20. Ternary diagram with texture data of brown loam deposited on the Pleistocene terraces. Texture of soil was determined with the standard method A.

Table 28. Texture data after pretreatments with sodiumacetate buffer pH 5, 30% hydrogen Superoxide and 0,2 N hydrochloric acid; dispersion agent sodium pyrophosphate, (method B.; sample Region depth 2-0,5 0,5-0,21 0,21-0,05 50-20 20-10 10-5 5-2 number in cm mm mm mm u. M- IJ- V- <2 (j.

15 I Balikh 0-12 0,08 0,1 0,4 4,2 9,9 4,9 6, 3 74,0 P.'j 15 II 15-25 0,2 0,1 0,6 2,8 7,8 3,7 6, 1 78,8 15 III 40-50 0,3 0,1 0,5 2,8 5,7 3,9 5, 5 81,2 6i' 1 15 IV 90-100 0,2 0,1 0,5 4,7 5,8 5,6 7, 8 75,2 sample Region depth 2-0,5 0,5-0.21 0,21-0,05 50-20 20-2 number in cm mm mm mm U U <2n 16 I Volcano 0-4 40,8 10,2 12,4 18,4 8.8 10,3 16 II 20-30 40,5 9,4 11,8 14,3 13,3 10,7 16 III 60-70 54,0 7,0 6,9 9,3 12,7 10,0 16 IV 145-155 70,7 16,0 5,4 1.6 2.4 4,0 30 I Gypsum 0-5 1.1 4,2 12,0 18,1 29,5 35,1 30 II 8-13 1.3 3,8 18,5 24,1 22,3 30,1 30 III 20-30 1.9 3,3 15,1 23,6 23.5 32,7

note: The results with method A of profiles 15, 16 and 30 are given in table 30.3, 30.10, 30.8 respectively. 115 Table 29. Texture of gypsum soil as determined by sieving methods.

Sample depth in number cm >50'Op. 50-500 IJ, < 50 M.

30 IV 35-45 5, 5 50,0 44,5 30 V 55-65 6. 7 61,0 32,3 30 VI 80-90 36. 0 28,7 35,3

3. DESCRIPTION AND ANALYSES OF THE SOIL PROFILE

Chemical and analytical data together with the profile descriptions are given in table 30. Methods of analysis are described in section A, 1 of this chapter and section B, 1 of chapter in. For notations of clay and silt fraction minerals one is referred to section B, 1 and C (table 21). of chapter HI, and for mapping methods and field classification symbol to chapter Vu.

a. Soil horizon designations.

The ABC soil horizon designation enables one to rapidly recognize genesis with the aid of a symbol. Generally the properties of arid soils are dominated by authigenic carbonate which overshadows the non-carbonate material. The original designation C is unsatisfactory because it fails to indicate the dominant soil properties. Gile, Peterson and Grossman (1965) proposed the introduction of aK-horizon, defined as follows: an horizon showing a prominent accumulation of fine- grained authigenic carbonates, which coats or engulfs skeletal pebbles, sand and silt grains as an essential continuous medium (K-fabric). Since the profiles examined by these autors all had a high content of fine sand, the calcitans of the skeleton grains easily could be connected owing to the small distance between these grains. A continuous calcareous fabric was not found in the Aridisols of the Balikh Basin, these soils requiring a very high percentage of carbonates for developing a continuous K-fabric due to their high content of clay and fine silt. However, the calcic horizon found in the soils has a lot of properties in common with the K-horizon. Therefore, horizons showing a prominent accumu-

116 lation of fine-grained authigenic carbonates and a high content of clay and fine silt are indicated with the symbol (K). Thé following soil horizon designations are used: (A ) an ochric epipedon with a crumbly structure. (A..) an ochric epipedon with a platy structure. (A ) an ochric epipedon with ploughing practices. (B) a cambic horizon having textures of loamy very fine sand or finer in the fine earth fraction, a crumbly to subangular blocky or blocky structure and showing evidence of removal of carbonates. (K..) a transition to the calcic horizon having lime accumulations (less than 5 percent by volume), 35 percent or more by volume of fine-grained authigenic carbonates in the soil plasma and a slightly hard blocky structure. (K ) a calcic horizon having many lime accumulations (more than 5 percent by volume), 50 percent, or more by volume of fine-grained authigenic carbonates in the soil plasma and a hard blocky structure. (K ) immediately underlying the calcic horizon and having lime accumulations 3 (less than 5 percent by volume), 35percentormorebyvolumeoffine- grained authigenic carbonates in the soil plasma and ahard blocky stucture.

C soil parent material which is unconsolidated and does not show properties diagnostic of the other master horizons. C C-material with a gypsic horizon; structureless, cs C C-material with some lime mycelia. ca J C .. C-material with vertic properties e.g. cracks and slickensides. He indicates material being different from the C-material.

117 TABLE 30i PROPILE DESCRIPTION CHEMICAL AND ANALYTICAL DATA OP SOILS OF THE BALIKH BASIH. TABLE 30.1: TYPIC TORRIFLtJVENTS. Sample Textura U.S.A. iSxchangeabla baaaa na/iOO K C.iäTi Sample depth aand ailt clay Sun >e/iOO | * * number gravai 2BD-5OH 50-2 u 2M C/B CaCO. gypaum 20-1 0-5 17,0 60,9 22,1 0,74 0,09 8,2 20,1" 12,4 5,38 I ,05 0,22 19,1 19,1 1,15 3,90 20-11 30-35 6,3 68,1 25,6 8,6 - - - 21,3 14,3 6,53 0 ,96 0,33 22,1 22,1 1,49 2,64 20-111 6O-65 30,6 59,7 9,5 8,8 - 20,1 8,61 3,43 0;,84 0,19 13,1 13,1 1,45 20-IV 85-90 1.9 72,9 25,2 8,4 - 23,1 0,03 18,2 5,43 0.,27 0,51 24,4 24,4 2,09 3,16 521 20-30 27,0 54,3 18,7 8,2 0,53 0,08 6,6 14,7 0,42 6,90 6,72 0 ,62 0,40 14,6 14,6 2,74 26,0 52II 5O-6O 34,9 55,7 8,4 8,4 - '4,5 0,42 5,82 6,86 0:,32 0,60 13,6 13,6 4,41 14,4

ie/100 i

10 Ca «g K Ha Sum HCO, CI S0J HO, 0,64 1,42 0,89 0,21 1,06 3,58 3,01 t7 0,59 0,75 1,63 0,04 0,50 0,87 0,57 0,13 0,75 2,32 2,43 tr 0,52 0,78 1,10 0,03 0,27 0,40 0,21 0,14 0,44 1,19 1,22 tr 0,47 0,26 0,49 tr 0,64 1,16 0,57 0,03 1,25 3,01 3,17 tr 0,47 0,69 2,00 0,01 3,84 8,34 7,58 0,22 6,33 22,5 22,2 tr 0,31 12,2 9,60 0,12 2,70 7,49 5,29 0,08 4,59 17,5 17,0 tr 0,28 4,78 11,9 0,02

Chemical and minéralogie*! i of the clay fraction (< 2 n )i

Sample Clay Minerals •umber 20 I 56 ,7 15,6 9, 4 4,6 1,1 3,9 2,3 93,6 6, 2 16,3 2 ,6 Ho Chi P I If a 20 II 56 ,2 t5 ,9 9, 6 3,1 0,9 1,6 2 , 1 89,4 6, 0 15,6 2,6 Ko" Chi* P I* K* a 20 in 56 ,0 15 ,9 8, 5 3,6 1,5 2,4 2,2 90,1 6, 0 17,6 2 ,9 «o** Chi* P I* K a 20 IV 54 ,8 16 ,o 8, 9 3,7 0,9 3,6 2,0 89,9 5, 9 16,6 2 ,8 Mo** Chi* P I* K a

Chemical analyses of total soil sample (< 2 i Sample Al_0, Fe.i MgO CaO »a-O K-0 .otal ^°2 number 20 I 43,8 6,5 6,3 5.0 9.1 6,3 1,6 0,2 78, 8 11 ,6 18, 7 1 ,6 20 II 41,8 7,6 6,3 5,0 10,2 4,0 1,6 0,2 76, 7 9,4 17, 8 1 ,9 20 III 40,7 6,8 6,0 4,7 11,8 3,6 1,5 0,2 75, 3 10 ,3 18, 3 1 ,8 20 IV 38,2 6,7 6,6 5,4 12,6 5,1 1.4 0,2 76, 2 9,8 15, 9 1 ,6

TABLE 30.2: TYPIC USTIFLUVENTS.

•ample texture U.S.A. Exchangeable baeea me/100 K C.E.C. Sample 4£*h clay Ca Mg .e/100 g •umber cm gravel 2am-5O 5O-2 M <. 2 u » C/H 7 I 0-10 2,6 83,1 14,3 0,93 0,15 6,2 27,5 26,5 4,06 2,45 0,18 T37T- 33,2 034~ 30-40 2,3 57,2 40,5 26,2 26,2 5,55 1,94 0,18 33,9 33,9 0,53

1 I ECa 5 water extract Oe/i00 g -5 ations Ca K Ha Sum Sum CO3 HC 0. Cl »g M4 B03 0,19 0,86 0,11 U,15 0,15 1,27 1,19 o, 78 tr o, 39 0 ,02 0,17 0,80.0,12 0,09 0,13 1,14 1,06 o.65 tr 0, 40 0 ,01

118 Profilât 20. Hst« of obB«rratiom April 1966. Loc»tioni Eupfcratea valley, fiaq.q.a Saura Uaetije. Elevation! 240 a. Baliafi flat on 5» distance of a shallow dry rivar channel. Land usai cotton. Parent material! Holocana Euphrates lowest terrace. Soil conditional slightly aoiat to slightly wot. Soil Burfaoet ploughed.

Field classification! AOLr. Soil typei Typic Torrifluvent.

( A ) 0-13 ca Slightly moist, light olive brown ( 2-5 Y 5/4) ailt loam, rooted,containing very little organic material, soft sedimentary mi crop la ty fabr ic • soft weakly de v© loped crumbly to suban^ulap bl ocky a true tur$ with many biopores * merging ^3*sdually into 1 C. 13-45 cm slightly moist, oliv» brown { 2.5 Y 4/4) eilt loan, rooted, soft weakly developed crumbly to aubangular blocky structure vith many biopores, sedimentary platy fabric and occurrence of clay loam bandst merging gradually intoi C 4^-30 cm olightly aoiat to slightly wat, olive brown ( 2.5 Y 4/4) ailt loan, poorly rooted, very weakly nottled, very aoft consistence, micropores, sedimentary platy fabric, occurrence of clay loan bands) merging rather quickly intot C 6O-97 cm slightly wet, olive brown to very dark greyish brown ( 2.5 Y 3/3) eilt loan, poorly rooted, weakly mottled, soft consistence, few biopores, sedimentary platy fabric and occurrence of some sandy bands.

Profile 1 52 Dat« of observation! April 1966. Location! south-east of Bamret Jamati. Elevation1 237 a. Seliefi flat. Land use! fallow. Parent material! Euphrates alluvium. Soil conditional aoist.

Field classification) AOUa^

Soil typ«1 Typic Torrifluvent

(A. ) 0-10 cm Moiet, light oliv« brown (2.5.T 5/4) ailt loan, containing littl« organic material, weakly developed soft crumbly structura)

merging gradually intoi Cj^ 10-75 cm aoiat,olive brown (2.5 Y 4/4) silt loam with salt «ccunulations, sedimentary platy fabric! merging gradually iatoi

C2 75-100cm noiat, olive brown ( 2.5 Y 4/4) sandy ailt loam with salt accumulâtions and micro-platy fabric.

Profilai 7-

Date of observationi March 1966. Location! aouth-west of Bavïje. Elevation! 29Ö m. Belief! valley bottom. Vegetation! grasa. Parent material! Wadi al Cbeder alluvium, flood plain. Soil conditions! moist.

Field classification! AOL/Clr Soil typei Typic Uatifluvent.

(A^) 0-20 en Hoiat, strong brown (?.5- YB 4/6) silt loam, containing littl» organic material, weakly developed aoft crumbly structurel merging intoi

c 1 20-50 cm moiet, strong brown (7.5 YB 4/6) silty clay, Bottled, fine platy fabric, small limeatone blocks) merging into!

C2 50-IOOcm moist, dark brown (7.5 YB 4/4) day, Bottled, fin» platy fabric.

119 TABLE 30.51 VERTIC USTIFLUVENTS. T.Ttur. U.S.A. pH Orn»nio oattar Sauplo dapth sand silt clajr nuabar grav«: 5O-2 li C B C/B CaCO JpIlUB C« MS. t Ha Sua n./lOO g B.5.P. ca 2aa-5O u u * 2 U S 15-1 0-12 0 6,9 41.2 51,9 8,1 1 ,04 0, 0 10,0 27,6 tr 26 ë fitl* 2 ,53 1 .32 39, 1 39,1 3.38 15-11 I5-25 0 4,8 38.0 57,2 8 ,2 - - - 29,3 tr 25 2 9.97 2 ,00 0 .78 38, 0 38,0 2 .05 15-III 40-50 0 3,4 30,9 65,7 8 ,3 - - - 32,4 tr 22 2 8 .04 0 ,89 0 .41 31, 5 31,5 1 ,30 15-IV 90-100 0 1,7 35,2 63,1 8 ,5 - - - 33,1 - 21 5 1 1.9 1 .65 0 .39 35, 4 35,4 1 ,10 1 1 5 "»ter extract ae/100 g ffi cations ani ono 3 5 ,3 x 10 x ÏO Ca "g n Ha Sua Sua CO HCO. Cl S0„ "°i 5.15 1,50 5.59 2,16 0,10 2.67 10,5 10,5 tr 0 ,36 0,87 9,19 0,08 3.22 0,72 0,34 0,92 0,46 0,01 0,41 1,80 1,91 tr 0 ,46 0,46 0,89 0,10 - 0,25 0,53 0,35 0,02 0,44 1 • 34 1,37 tr 0 ,55 0.21 0,57 0,04

Cbaaica1 and ninaralogical analysas of the clay frac ion ( 2 u) .

1 nuabar Al P.2O, *2°, IS ! y 5" y * Q p 15 III 48,6 15,1 8, 4 4,7 05, 2.3 2,1 81,1 5,5 15,6 2,8 Mo Chl p* 1** « * y p 15 I' 51,4 16 ,0 8 6 5,5 05, 0,7 2,3 85,C 5.5 16,2 2,9 No Chl p* 1** * * y ?

Cbsaica 1 and ain• rai cgi cal analysas of ths silt frac ion 5-10

SiO2 P«2°3 "SO SiOj nuabar — 15 I 54,3 13,9 8,2 3,8 2,1 9,3 2,8 94, 4 17,8 2,7 M0 cm P 1 K

Saapl« nuabar 15 I 43,1 6,8 5.7 4.2 14,5 3,4 1.7 0,1 79,5 10,9 20,5 1,9 15 II 41,5 ',5 5,8 4.3 15.5 2,8 1.7 0,1 78,2 11,0 19,2 1,8 15 III 38,3 6,2 5,7 4.7 16,5 5,8 1.7 0,1 79,0 10,6 16,2 1,7 15 I» 37,8 7,0 5,7 4.8 16,7 2,3 1.7 0,1 76,1 9,3 18,0 1,9

aaapla TTtur« U.S.A. Organic Mtt«r ng+abl* btni a«/iOO g Saapl« C.E.C. d«ptb * •and silt clay TT B*/1OO g nUBbar gravel 2aa-5O u 5O-2U < 2 u C/N 1S-I 2-7 n.a. n.a. n.B. »,J 1,31 0,14 9,4 21,5 - 24,5 9, 26 2.25 0,58 36,6 36,6 1,59 19-11 20-25 1,6 32,1 66,3 8,5 20,9 t r 26,3 11 ,4 1.79 1,08 40,6 40,6 2,66 19-111 6C-65 1,1 12,2 86,7 8,4 22,0 t r 21,5 14 ,1 1,64 1,25 38,5 38,5 3,25 19-lï 90-95 1,2 39,8 59,0 8,4 22,3 0 ,02 20,8 16 ,1 1,47 1,08 39.5 39.5 2.73 19-» 140-150 1,0 51,0 48,0 8,0 21,2 28,1 9, 44 2,73 0,47 40,7 40,7 1,16 27-1 0-5 5,6 55,1 39,3 8,0 0,59 0,09 6,6 29,6 tr 19,6 7, 35 1,73 0,36 29,2 29,2 1,23 27-11 15-23 5,2 49,2 45,6 8,0 30,3 tr 18,6 9, 59 1,35 0,34 29,9 29,9 1,14 27-111 40-50 5,1 41,2 53,7 8,3 30,6 - 15,7 11 ,4 1,16 0,46 .28,9 28,9 1,59 27-IV 70-80 4,0 41,9 54,1 8,4 30,0 - 12,8 15 ,0 1,02 0,71 29,5 29,5 2,41 51 I 0-10 2,2 66,9 30,9 7,7 0,76 0,11 6,9 25,5 1 .13 20,4 12 ,6 2,63 0,93 36,6 36,6 2,54 51 11 30-40 1,7 28,5 69,8 7,8 27,3 0 • 34 20,5 11 ,6 2,13 1,56 35,8 35,8 4,36 51 III 70-80 1,4 17,7 60,9 8,1 25,9 0 ,03 16,5 14 ,9 1,91 0,93 34,2 34.2 2,72

et rue t m/iOO g

"ÖT3S" na ru» o,73 nu1 - 0,36 n.n. TUB na no na na na na 1,00 na1 2,12 0,49 0,62 0,77 0,05 0,93 2,57 2,62 0,66 0,25 1.71 tï 3,14 0,70 0,98 i|25 0,06 1,27 3,56 3,43 0,60 0,96 1,87 ti - 0,41 1,00 0,53 0,14 0,31 1.98 1,97 0,62 0,25 0,82 0, 08 2,22 0,49 1,31 0,58 0,06 0,57 2.54 2,50 0,50 0,43 1,20 0, 37 2,04 0,43 1,21 0,69 0,04 0,40 2,34 2,33 0,52 0,34 1,14 o. 33 - 0,31 0,55 0,48 0,02 0,54 1,59 1,57 0,63 0,25 0,57 0, 12 - 0,34 0,46 0,56 0,01 0,81 1,84 1,73 0,65 0,25 0,69 0, 14 4,52 2,92 14,1 6,1 0,16 1,83 22,2 22,2 0,40 0.58 21,1 0, 07 4,58 1,56 6,33 2,67 0,09 1,80 10,9 10,9 0,45 0,70 9,75 0, 03 4,50 0,92 1,78 1,25 0,06 1,11 4,14 4,10 0,54 1,30 2,26 ;r

120 Profil«! 15. Location 1 north of Etsiaah. Dat« of observation 1 Àuguat 1965. Elevation • 270 a. Relief • flat. Land uae 1 ootton.

Soil conditiona 1 >oi«t to wet| Irrigated 15 *»*• *«°- Pield classification 1 AOClhrv. Soil type • Y«rtlc Ustifluvent.

( A., ) 0-12 OB Motet,dark brown ( 13 TB 3/3) «ilty clay, containing organio «atter, poorly rooted, the upper 3 ca have a platy structure, 3-12 ce aoft crusbly atruotur«, cracks on surface 1 aerging Irregular intoi C 12-26 en Vet, dark yellowish brown ( 10 TB 4/4) clay with black organic «pota { 10 TB 2/i ), «oft fine platy «ediaentary fabric, poorly rootedi aargiog gradually intoi C12 vertic wet, dark yellowiah brown { 10 IB 4/4) olay, accumulation of clay and black organio material in cracks, aottled, «oft fin«

26-100 CB _,_... __„. ,.h,,._ lnn.lW -liek.n.idee. .„„in. intoi

C13 100-200 ca wet, brom ( 7-5 ™ SA) olay with BOttl««, «oft fine platy aediaentary fabric.

Profil« • 19. Sate of observation • March 1966. Location 1 north of Baqqa Saura. El«Tation • 241,5 a. Relief l.flat. Native vegetation 1 buahe«. Land use 1 liquorice plant.

Soil condition« • aoist to alightly wet. Soil surface • weakly developed gilgai relief. Pleld classification 1 AOClrbv. Soil type 1 Tertic Uatiflurent-

(1 ) 0 - tl ca Moist, dark brom (7-5 TB 4/4) clay loam, containing vary little organic Material, poorly rootad, weakly Bottled, aany crack«, 0-0,2 ca platy fabric, tendency to orunbly structure, nonp.la«tlc| »erging gradually intoi C vartio 11 - 86 ca «lightly wat, dark yellowiah brown (iO TB 3/4) olay, aany old root fragnanta, poorly rooted, crack« ar« partly inhubittid up to 86 ca by root« with a maximum diameter of 3 ca, Bany mottle« between 11-24 cm amd 64-66 ca, aaall clay-bunua accumulation», «oft plastic sedimentary micro-platy fabric, aany »licken»id»s I Barging gradually intoi C - 86 - 105 ca aoiat, dark brown (7-5 TB 4/4) clay, vary auch aottled, soft plastic s«diB«ntary micro-plat y fabric

Profil«1 27. Sate of observation! May 1966. Location! east of Eaiimah. Elevation 1 265 a. Reliefi flat. Land usai cotton. Parant material 1 Balikh alluviua. Soil conditional «lightly Boi«t. Soil surface! ploughed.

Pield olas«ificationt a0-I Clhrv. Soil typei Vertic Uetifluvent.

(a ) 0-10 ca Slightly mo iet, dark yellowiah brom ( 10 TR 4/4) ailty clay loan, containing little organic material, poorly rooted, medium hard fine to nediu» blocky «tructur«, «ticky when wet; aerging gradually intoi

C11 10-35 ca moiat. dark yelloviah brown (10 TB 4/4) ailty clay, containing little fine gravel, intensively strong brom aottled ( 7.5 TR 5/6}, having vertical tongue» of dark yellowish brown clay, poorly rooted, aoft to medium hard «ubangular blocky to blocky »tructure, internal aicroplaty fabric, sticky when wet, Barging gradually intoi C12 vertio 35-70 cm »lightly ooiot, dark yellowish brom (10 TB 4/4) silty clay with atrong brown (7-5 TB 5/6) mottle», having nose dark yellowish brown tongue», very poorly rooted, very hard angular blocky »truetore to locally «harp wedged struotur« (parallelopipada), with »lieken»idea on the«« «harp «edged elenentsf merging gradually intoi C 13 vertio 70-160 ca «lightly mo iet to dry, dark brom (7-5 TB 4/4) «ilty clar with brom (7-5 TB 5/4) aottl«s, with BOB« dark y«llowiah brom tongute up to 1 a, very poorly rooted up to 1 B, b>rd angular blocky atruotur«, locally »lickenaidee on parallelepiped structural aggregate».

Profilai 51 Dat« of observation! March 1966. Location! north-west of Bhayat. Elevation 1 260,5 a. Heli.fi flat. Land usai cotton- Parent material 1 Balikh alluvium. Soil condition»! aoist. Pield classification 1 AOL/Clr(bvc) Soil typet Tertio Datifluvant

(*,) O-30 ca Moist, dark brown ailty clay loan, containing little organio aaterial, weakly developed «oft orunbly structure, strongly nottied( aerging gradually intoi CH 30-40 ca aoiat, dark yellowish brown clay, fine platy fabric, Bottled, faw 11B« accumulation»! Barging gradually intoi C12 Tertio 40-100 CB moist, dark yellowish brown silty clay, fine platy fabric, few lia« and g7p»uo accumulation», »lickeneide«.

121 TABLE 30 .4; TYPIC CALCIORTHIDSi LOAMÏ OF HZ TEREACE RECIOH. sample Texture U.S.A. pH Organic matter Exchangeable bases me/100 g C.E.C. depth Saiapl« sand silt clay Ca Kg K Ha Sum me/100 g in t V * * % nuabar cm gravel 2nm-5Ou 50-2 n <. 2 V C I C/J CaCO. gypOUD 5-1 0-8 0 10,5 72,3 17,2 8,7 1,19 0,14 17,7 - 27,4 2,68 2.94 0,09 lt.1 33,1 5-n 15-25 1,5 8,5 63,4 28,1 8,9 21,7 24,6 3,36 2,71 0,07 30,7 30,7 5-111 40-50 1,5 7,1 61,9 31,0 8,9 25,8 25,0 4,12 1,20 0,10 30,4 30,4 5-IV 75-85 1,5 20,5 50,0 29,5 9,1 24,9 27,4 1,42 0,43 0,18 29,4 29,4

œe a«/100 g E. S. P. EC *> , oati on. aniono z 10J Ca Va Sum Sua CO, HCO. Cl K »o3 0,27 — 0,14 0,57 0,0. 0,12 0,07 0,00 1,46 tr 0,66 tr *>0,7„7 0,03 0,23 0,14 0,45 0,08 0,12 0,08 0,73 0,62 0,60 0,02 0,33 0,13 0,45 0,04 0,01 -0,20 0,70 0,62 0,60 0,02 0,61 0,16 0,42 0,02 0,01 0,38 0,83 0,67 0,64 0,03

Chsaioal and mineralogies! analysas of the clay fraction (< 2u)i Sanpls SIO, SiO, «1.0 KgO CaO Ba O Clay alnsrals numbsr 2W3 2 5 I 49,9 20,3 8,3 1,6 1, 3 5.0 4,6 91,0 4,2 16,2 3,9 Ho Chi P I 4 7 5 II 46,6 19,7 7, 9 »,8 0,4 4,7 3,4 84,5 4,0 15,8 3• 9 Ko Chi P l" 4 7 5 III 49,5 20,8 7, 1 1,8 0,4 0,9 3,6 84,1 4,1 18,8 4,6 Ko Chi P l" 4 7 5 IV 46,4 18,9 9,2 0,6 0,5 2,5 3,3 81 ,4 4,2 13,6 3,2 Ko Chi P I" 4 P

ChiBical and ninaralogical analyeos of tha oilt fraction 20-30 111 Sampl« Al O F* 0-. MfiO CaO Ma 0 sio2 sio2 nunbtr 5 I 83, 8 5,4 0,6 0,0 0,5 3,9 1,8 96,0 28,0 13,"0 Ko H 5 II 81, 4 5,7 0,7 0,4 0 ,5 5,0 2, 1 95,8 24,1 13,8 Ko H 5 III 81, 1 6,2 0,9 0,7 0 ,6 4, 3 2, 1 95,9 22,5 10,2 Ko X :4T y 5 IT 81, 4 6,8 1,1 0,3 0,6 3,5 2, 1 95,8 20,4 11,2 Ko H

Tsiturs U.S.A. Organic mattsr Erohang«abl*> ban nu m«/.00 g C.K.C. • Saapls dflptb aand ailt clay numb.r ** 2BO-50 v 50-2n C/H CaCO. gypsi Ca Mg K Ha Sua os/100 g E.S.P 24-1 0-8 34,1 58,07,9 0,60 0,09 6,7 16,7 T^ Ï767 0,13 20,5 0,64 24-H 8-15 1,5 23,9 56,2 19,9 0,30 0,09 3,3 17,3 2,88 1,02 0,16 21,4 21,4 0,75 24-111 25-35 1,5 20,4 47,5 32,1 8,6 17,2 3,91 0,43 0,27 21,6 21,8 1,24 24-IT 70-80 3,5 20,8 47,0 32,2 8,7 14,6 3,99 0,16 1,74 20,5 20,5 8,50

1 t 5 vat«r «tract M/100 g œe cation» ons Ca Kg K Ha SUD Sum C °3 BC03 Cl SO. B03 - 0,13 0,44 ,01 ,56 ,52 - 0,21 0,79 0,10 0,04 0,19 1,12 0,97 tr 0 ,51 0,25 0,20 0,0 — 0,43 1,11 0,24 0,01 0,89 2,25 2,01 tr 0,40 0,89 0,07 0,65 5,63 0,65 1,01 0,28 0,01 2,03 3,33 2,94 tr 0,45 1 ,43 0,33 0,73

Ch ffllcaland Binerai Oglca1 analyses of the clay fraoti n (*.2 V. , Sample SiO, SiO I A12O i SiO, ?• 'eo CaO Ha20 K Total Clay mi 10 rals number "2°3 2°3 F.2O 3_ 24 I 52,0 17,2 a 5,1 0,6 4,9 2,6 90,8 5,2 16,7 3,2 Ho Chl P' l'* K 4 7 24 r* ++ 24 III 53,0 16,8 8,1 5,4 0,8 3,4 2,3 89,8 5,4 „ ,7 3,3 Ho Chl P* 1 K* 4 F + 24 I» 55,2 15,6 7,6 7.1 0,7 2,9 1,9 91,0 6,1 19,6 3,2 Ho Cbl p" 1 K Q P

anal • (< 2mm) Sampl« MgO CaO nuab«r 24 1 48,6 9,7 5,4 3,5 0, y z,6 ,4 0,2 00,3 tj, 5 24,5 2,9 24 11 47,2 9,7 5,5 4,2 9,8 2, 9 1,4 0,2 80,9 8,3 23,1 2,8 24 m 37,7 10,0 3,5 4,2 10, 4 4, 2 1,5 0,2 71,7 6,4 29,9 4,7 24 IV 37.7 8,7 5,1 4,3 12, 7 4, 5 1,2 0,1 74,3 7, 4 20,3 2,7

122 Profil« i 5. Date of observationi June 1965. Location* Hanret terrace, east of Sbininah. Blsvationi 259,3 »- Eeliefi flat to faintly «loping. Lind us« »ad native vegetation) oereals and thistles. Parant materiali loamy o over on Middle Pleistocsna terrace. Soil conditional dry. Fiald classification! JLoLb.

(A ) O - 8 on Dry, light yellowish brown (lO TB 6/4) silt loan, containing little organic material, well rooted, 0-2 cm platy structure, 2-8 en soft to slightly hard crumbly structure! merging gradually intoi (B) 8 -26 cm dry, reddish yellow (7.5 TR 6/6) silty clay loam, wall rooted, soft to slightly hard crumbly to subangular blocky structure; marging gradually intoi

(K2) 26 -67 cm dry, strong brown (7-5 TH 5/8) silty clay loam, containing few lapilli, poorly rooted until 50co, slightly hard subangular blocky to blocky structure, many hard white lime concretions) marging gradually intoi (Kj) 67 -100 en moiat, strong brown (7.5 TR 5/6) clay loam, containing lapilli, hard blocky structure, small dark brown clay humus accumulâtiona, soft small lime accumulationst marging gradually intoi C 100 -220 cm dry to slightly moist, strong brown (7.5 TH 5/6) loam with intercalations of thin lapilli layer«, soft structureless, locally small spots with lime-nycelia) lying over gravel.

Profile 1 24. Date of observation! June 196S Location t Haqqa terrace. Elevation 1 268 n. Relief t flat to faintly aloping. Land use 1 cereals. Parent material 1 loamy cover on Upper Pleistocene terrace. Soil condition»! dry. Soil surfaoe 1 ploughed. Field classification 1 ÀOLb. Soil type 1 Typic Caloiorthid.

(A ) 0 - 8 CD Dry, yellow (1O TH 7/6) *ilt loan with some fine gravel, containing little organio material, poorly rooted, soft crumbly etruoture) aerging gradually intoi (B) 8 - 15 em dry, yellow (lO TH 7/6) silt loam, containing very little organio material, very poorly rooted, slightly hard crumbly structure, few soft white lima accumulations merging gradually intoi (K^) 15 - 43 cm dry, reddish yellow (7.5 TR 6/6) silty olay loan, Yery poorly rooted up to 40 cm, hard granular to subangular block? struoturs, «ome clay-humus accumulation», many slightly hard liaeconcretiona; marging gradually intoi

(K2) 43 - 100 cm dry, etrong brown (7.5 TB 5/8) silty olay loan, very hard subangular blocky to angular blocky atruotur», aome olay-humua accumulations, bard white lime concretion» abundant) merging gradually intoi

123 Exchangsabl. bass« m./ico g Supl« T.xtur» U.S.A. Organic oatt.r dspth Saapl. ID Band silt clay nusbar 5O-2U C/B ypBUB Ca «« Ba SUB os/1 CO g 31-1 0-3 2,5 THTT ~5576 5,7 »,0 19,! lé,6 2,36 2,20 0,17 2Î73 2TT3 31-11 6-12 1,6 29,9 61,1 9,0 8,2 23,4 14,7 2,22 2,10 0,17 18,6 18,6 31-III 25-30 1,6 29,9 50,0 20,1 8,2 27,9 10,6 4,48 1,23 0,38 16,7 16,7 31-IV 50-55 0,8 38,3 32,7 29,0 8,7 26,1 8,37 5,70 0,48 1,02 15,6 15,6 31-» 80-85 35,4 38,6 26,0 8,5 24,8 7,57 8,27 0,25 1,51 17,6 17,6

5 water extraot me/i00g cationa E.3.P. : 10J »Ï0* Ca «6 K

0,80 - 0,20 0,58 0,15 0,15 0,17 1 ,05 0, 96 tr 0,69 tr 0,20 0,07 0,91 - 0,14 0,42 0,11 0,12 0,14 0 ,79 0, 78 tr 0,64 tr 0,14 tr 2,28 2,26 0,42 1,09 0,34 0,07 1,12 2 ,62 2, 55 tr 0,52 0,62 1,31 0,10 6,54 4,10 0,55 0,69 0,24 0,01 1,95 2 ,89 2, 64 tr 0,53 1,69 0,36 0,26 e,5d 6,40 0,98 0,59 0,70 tr 3,52 4 ,81 5, 05 tr 0,41 3,32 1,01 0,31

Chenlcal and D literal ogical analyses of tha clay fraction (v 2n)i

Sample Al O Fs?0. MgO Clay ninarals Buab«r 31 50,2- 16,3 B,4 5, 3 3,1 Chi 9 F 31 II 53,4 15,9 8,8 5,0 o, 7 1 2,5 87,4 5, 7 16 ,2 2,8 Chi « F 31 III 49,5 15,2 8 ,7 4 ,6 0, 6 2, 3 2,3 83,2 5, 5 15 ,3 2,8 « F 31 IV 51,1 14,8 7 ,9 5,1 0, 7 4, 1 2,1 85,8 5, 9 17 ,4 3,0 Chi 9 F 11 V 58,1 12,7 7,2 7,1 0, 6 2, 7 1,5 89,9 7, 8 21 ,5 2,8 Cfal S F

Ch«airal analyses of total soil saapl* (v2 ffla)i

Sampl« nuab.r- 5,e 4,6 13,0 3,9 1,6 0,2 88,6 11,3 31 II 49, 1 7,6 5, 6 4 ,6 15,5 5, 1 1,6 0,1 89, 2 11, 1 23, 4 2, 1 31 III 45, 4 7,0 5, 1 4 ,6 17,2 5, 7 1,4 0,1 86, 5 11, 1 24, 4 2, 2 31 IV 46, 6 7,6 4, 9 4,5 15,5 3, 8 1,2 0,1 84, 2 10, 5 25, 9 2, 5 31 V 46, 6 5.2 5, 1 4 ,4 14,5 5,2 1,1 0,1 82, 2 1», 5 25, 0 1, 6

Sanple Textura U.S.A. Organic nattar Exchangeable baaaa ne/100 g Sa.pl. sand o lay nunbar 2 mai-JOu '2H C/H CacO, Ca Na Sun ma/100 g 18-1 0-10 18, 9 64,0 17 ,1 8, 9 0,80 0,10 18,4 24.7 2,67 2,72 0,09 30,2 30,2 18-11 10-20 13, 3 62,7 24 ,0 9, Ü 23,1 22.8 3,24 2,53 0,04 28,6 28,6 18-111 35-45 5 11, 2 72,7 16 ,1 8, 8 - - 23,6 20,6 4.05 1,41 0,11 26,2 26,2 18-IV 65-85 •> 13, 5 56,5 » ,0 8, 5 - - 26,8 12,6 4,06 0,52 0,10 17,4 17.4

; 5 watar extract na/l 00 g cationa

0,30 - 0 ,12 0,48 0,05 O.Ji 0,06 0,70 0,64 tr 57 tr »07 tr 0,14 - 0 ,12 0,34 tr 0,19 0,î5 0,68 0,59 tr 0, 59 tr tr tr 0,42 - 0 ,31 0,52 0,08 0,03 0,84 1,47 1,31 tr 0, 52 0,44 0 ,20 0,15 1,04 9 ,47 1 ,06 2,16 0,72 0,01 2,28 5,17 4,95 tr 0, 13 2,97 0 ,60 1,05

Saaple Texture U.S.A. Organic natter Exchangeable ba»es ae/lOO g pH Sa=pl. "•.£"> sand silt clay * nuaber en gravel 2mm-5Ou 50-2n <. 2u C S C/H CaCO, gypeum Ca Hg K Ha Sua 5 ,9 19 ,5 0,90 0,12 7,5 16,9 23,5 2,31 2,55 0,09 28,5 26-11 10-20 5 13,6 54,7 31 ,7 8 ,7 19,6 23,8 3,09 2,02 0,11 29,0 26-111 25-35 11 16 ,6 50,0 33 ,4 8 ,8 20,1 23,2 3,09 1,52 0,12 27,9 26-IY 50-60 10 14 ,2 66,7 17 ,1 e,8 26,7 22,0 2,90 0,31 0,13 25,3

1 t 5 water extract ne/i00 g C.E.C. »o/l 00 g .Ï.3 C* Ha Sum Sun CO, BCO. 28 ,5 0,32 0,14 0,48 0,12 0,13 0,06 0,79 0,75 - 0,64 29 ,0 0,38 0,10 0,25 0,11 0,08 0,09 0,53 0,52 - 0,52 27 ,9 0,43 0,11 0,25 0,08 0,04 0,14 0,51 0,51 tr 0,51 25,3 0,51 0,11 0,14 0,11 0,01 0,26 0,52 0,48 tr 0,48

124 Profil«i 31. Ott« of ob.. m t ion. January 1966.

Locationi north-weat of Kajle.

Blevs-tioni 263 B. Rsliefi flat. Xativ« vagatationt scarcely grass and low shrubs.

Soil conditional dry to •lightly aoist.

Soil fauna 1 BOM aata. Field clarification 1 ao{l)Lb. Soil typ«1 Typlc Caloiorthld.

(A ) 0-5 on Dry,light y«llowi«h brown (lO TH 6/4) »lit lo*» with wry f«w lapilli, containing little organic uttrUl, root«d, slightly

hard platy atructur«f margins quickly intoi (B) ^-20 o* dry, light ysllowish brown (lO TH 6/4) tilt loaa with vary fa« lapilli, poorly rootad, »lightly hard oruably to subangular blockjr structural merging rath«r quickly intot

(K21) 20-45 <>• **y to «lightly noiat, brownish yellow (lO TB 6/6) ailt loaa with vary fa« lapilli, «lightly hard cruably to «ubangular

blocky atruotur«, many «oft «bit« lin« accumulation*t Barging gradually Intoi

U22) 45-65 CB dry to alightly soiat, yellowish brovn (lO TB 5/6) clay loan with very f«« lapilli, alightly bard oruBbly to eubangular blocky structura, many aoft «hit« lia« accumulation«! a«rging gradually intoi (K ) 65-105 CB dry to slightly aoist, y«llo«iah brown {lO TH 5/6) loaa with fa« lapilli, hard angular blocky atruotur«, few aoft whit«

lia« accumulation«) a«rging gradually intot (K-,,) 105-125 OB dry to «lightly aoist, yallowiah brown clay loaa with fsw lapilli, soft whit« lia« accumulation«.

Profils » 18.

Dat« of obs«rv*tiom July 1965. •

Location1 Haaret t«rrac«.

Elevstioni 248,4 a.

lativ« vegetation! short dry grass. Parent aatarisli loaay cover of Upper Pl«iatoc«n« Euphrates tarraca.

Soil condition«! dry.

Soil faunas worn track«. Soil surfacei fox holes.

>i«ld olasaificationt AoLb.

Soll typ« 1 Typic Calciorthid.

(JL%) 0-10 CD Dry, T«ry pal« brown {lO TH 7/4) silt loaa, containing vary littl« organic ut«rial, rooted, aoft to slightly hard eruably atructur«, locally a platy structur« near th« aurfao«; B«rging gradually intoi (B) 10-24 ca dry, very pal« brown (lO TR 7/4) silt loaa, Containing very little organic «at«rial, poorly rootad, soft cruably to

blocky structure, few Una accumulation«( aerging gradually intoi

(K21) 24-55 ca dry, light, yellowish brown (lO TH 6/4) silt loaa, alightly hard to hard granular to subangular blocky structur«, BOBS

clay-huBus accumulations, aany slightly hard lim« concrstions; marging gradually intoi

U22) 55-102 cm dry to slightly aoiat, reddish yellow (7.5 Tfi 6/6) ailty clay loan with soae gravel, bard granular to subangular blocky

structure, aosa clay-hunus accuBulation«, lin« accuaulations, aarging intoi

(ï,1 ) 102 ca and dry, strong brown (7-5. TB 5/6) silty clay loaa, coapact consistence, occurrence of a pabble-cobble layer with lime •-p-r accuaulations under th« atone«.

Profile 1 26.

Data of observation1 auguat 1965.

Location 1 aouth of Ha«inaii.

El«vationi 297,5 =>• Beliafi flat, low. I>and ua«i cereal«. Parent aat«rialt loaay cover on Lover Pleistocene terrao«.

Soil conditions! dry to alightly noiet. Soil fauna1 very few wora tracks.

Field classification1 lOLb. Soil typei Typic Calciortbid.

(*1t) 0-3 ca dry, reddiah yellow (7.5 TB 7/6) oilt loan, containing very little organic «At«rial, w«ll root«d, soft platy structurai B«rging gradually intoi

(*12) 3-10 ca dry, reddiah yallow (7.5 TR 6/6) silt loaa, containing nry littl« organic aaterial, well rooted, slightly hard cruably

structurel Berging gradually intoi

(B) 10-24 ca dry,reddish yellow (7.5 TR 6/6) silty clay loaa, poorly rooted, soft to alightly hard crumbly •truetur«merging gradually intoi

(K1 ) 24-40 ca alightly aoist, yellowish red (5 TR 5/6) silty clay loam, poorly rootad «lightly hard blocky «tructure, clay-huaus accumulations, faw lia« accuaulations! aerging gradually intoi (Kg) 4O-II5 ca aoist, y«llowish red (5 TB 4/8) clay loaa with soae fine gravel, very poorly rooted up to 55 cm, hard blocky structure,

clay-humus accumulation«, nmny lia« concretions; marging gradually intoi

U3) II5-145 cm slightly aoist, yallowish red (5 TB 5/8) loaa with soae fine gravel, few lime concretions! Berging intoi C I45-170 cm slightly aoist, yellowish red (5 TR 5/8) loaa with SOB« gravel! lying ovar gravel.

125 suple C.E.C, Saaple depth Texture U.S.A. Organic natter Exchangeable baaoa pe/lOO g •lit clev mimbar C/S * gypsum SUD- se/l 00 g 50-2|i <. 2u CaCO, 32-1 0-10 7 30,3 47,5 22,2 8 ,5 0, 90 0, 11 8 ,5 22,0 23,6 2,82 0,71 0,18 27,3 27,3 32-11 20-30 - 16,9 48,4 32,7 8 ,5 0, 38 0, 04 9 ,5 16 ,6 17,9 4,37 0,50 0,18 23,0 23,0 32-111 40-50 - 14 ,5 46,2 39,3 8 ,6 - 22 ,7 16,1 5,76 0,38 0,18 22,4 22,4 32-IT 70-80 13 22 ,4 39,6 38,0 8 ,0 _ 25 ,3 11,8 6,79 0,18 0,82 19,6 19,6

EC 1 • 5 • ater extract me/100 g E. 3. P. J cations anions xîo 3 X 10 Ca »g * Sa Sum Sum COj BCO3 Cl SI\ "°3 0,66 - 0*22 0,34 0,31 0,20 0,15 ,94 tr 0,05 0,78 - 0,21 0,46 0,36 0,07 0,24 1.13 0,90 tr 0 .64 tr 0,20 0,06 0,00 - 0,17 0,28 0,34 0,06 0,22 0,90 0,86 ' tr 0 ,65 0,20 tr 0,01 4,13 0,74 1.20 3,53 0,98 0,12 1,43 6,06 5,71 tr 0 .41 2,47 0,60 2,21

sample Texture U.S.A. d«pth Organic matter Saapl« eand eilt ola, number 2mm-5Ou 5O-2M <2n C/H CaCO, 3Ö-I 0-5 1 18,9 67, 7 13,4 a,7 1,15 07T3 8,8 17,0 38-11 10-15 1,5 12 ,6 65, 8 21,6 8 ,9 23,1 38-111 30-35 2 • 5 15 ,1 50, e 34,1 8 .6 24,1 38-IT 70-75 1 .5 12 ,4 53, 3 34,3 8 ,4 30,9 38-ï 105-115 1 ,5 11 ,5 44, 8 43,7 e,4 31,6

Exchangeable bas e s me/100 g C.E.C. œe 3 1 i 5 vater extract me/iCO g Ca »8 K Sa Sum me/100 g E.S.P. EC cations anione 3 X 10 Ca «g * Sa Sum Sum co3 HCO, Cl HO, "4 21,8 3,19 2,70 0,24 27,9 27,9 0,86 0,24 0, 47 0,10 0,09 1,10 1.76 1 ,2b tr 0,56 0,40 0,30 0 ,02 15,5 4,84 1,53 0,44 22,3 22,3 1.97 0,23 0, 32 0,10 0,02 0,62 1,06 1 ,02 tr 0,45 0,24 0,18 0 ,15 19,0 5,32 0,86 1,13 26,3 26,3 4,30 7 20 0,78 1, 38 0,28 0,01 2,17 3,84 3 ,17 tr 0,34 1,46 0,48 0 ,69 16,9 5,83 0,39 1,26 24,4 24,4 5,16 6 59 1,21 1, 07 0,65 0,01 3,98 5,71 5,62 tr 0,36 2,63 1,10 1 ,53 13,2 6,66 0,44 1,22 21,5 21,5 5.67 10 37 1,56 3, 84 1,20 0,01 4,49 9,54 8 ,15 tr 0,32 2,54 3,47 1 ,62

sample Texture U.S • A. p£ Organic matter Exchangeable bases ma/100 g c. E.C. S»mpl! depth * 0 in sand eilt clay Ba * * * number om gravel 2mn-50M 50-211 <• 2u 1 5 C s C/S CaCO, gyps om Ca »I Sa Sum me/100 g 42-1 0-3 0,7 23,6 50,7 25,7 8 3 0, 2 0,10 7,2 25,9 0,02 14 8 3, 24 2,57 0,37 21,0 21 ,0 42-11 3-14 2 20,3 54,5 25,2 8, 8 - - 28,5 - 13 6 3, 76 2,49 0,52 20,4 20 • 4 42-11 22-32 0 14,6 46,9 38,5 9, 3 - - 31,6 - 12, 0 5, 61 1 ,16 1,39 20,2 20 ,2 N 42-IT 45-55 0 13,1 65,2 21,7 9, 0 - - 29,6 tr 11, 1 6, 12 0,53 2,23 21,0 21 .0 42-ï 75-85 0 74,5 8, 1 - - 18,5 21,9 11, 1 5, 06 0,38 0,58 17,1 17 ,1

EC 1 • 5 water extract ma /too g E.S.P BC, cations ar iona J ,10 Ca »g K Sa Sum Sun CO, HCO3 Cl SO, ^4 1,76 1,80 0,57 1,13 0,33 0, 20 1,03 2 69 2,68 tr 0,53 0,33 1,18 0,64 2,55 - 0,28 0,29 0,11 0, 11 0,91 1 42 1,32 tr 0,87 tr 0,30 0,15 6,88 - 0,30 0,10 tr 0, 02 1,28 1 40 1,44 tr 0,90 0,25 0,20 0,09 10,6 3,70 0,58 0,24 0,02 0, 01 2,29 2 56 2,82 tr 0,68 0,75 1,21 0,18 3,39 5,94 2,76 15,2 2,92 0, 01 2,31 20 4 20,6 tr 0,22 0,96 9,3 0, 14

126 Profil«i 32. Dat* of observation) April 1965. Location 1 south of Haxiaah. Elevation) 297,4 •• Relief) flat. Land UMI vheat. Parant natariali loan; cover on Lover Pleistocene Euphratea terrace. Soil condition*) noiat to wet in th* topaoil. FitId classification! AoLb. Soil typet Typio Calciorthid.

(A ) O-IJ ca Wet, dark brown (7,5 YR 4/4) loan, rootad, friable cruably structure, fev lin«-aycelia| Barging gradually intoi (BJ 15-4O ca aolst, dark brown (7.5 TB 4/4) silty clay loan, poorly rooted, friable granular to crunbly atructur*, lime-oyceliat merging gradually iota 1 (K ) 4O-65 en moist, atrong brown (7.5. YH 5/6) «ilty clay loan, aubangular blocky atructur«, clav-humua accunulationa, aany lia« myceliai Barging intoi (Kg) 65-IOO en alightly Boiat, yallowiah red (5YH 4/0) clay loam, aubangular blocky atructure, clay-huau« accunulationa, lia« concrétion», Bottled.

Profilât 38. Data of observation) June 1965. Location* Haaret tarrac«. Elevation) 262,8 B. Relief) low, faintly sloping. Native vegetation) grass (scarce). Parent material) loaay cover of Middle Pleistocene Euphrates terrace. Soil conditions) dry. Soil fauna1 SOB* worn tracks. Field classification! AoLb. Soil typ*) Çypic Calciorthid. (*, ) 0-5 CB Dry, light yellowish brown (10 YH 6/4) silt loao, containing little organic material, 0-1 en slightly hard platy structure,

(B) 5-19 ca dry, yellow (iO YR 7/6) silt loam, containing BOB* fine gravel,poorly rooted, «lightly hard cruably to «ubangular blocky structur*j merging gradually intoi (K,) 19-50 cm dry reddish yellow (7.5 YB 6/8) ailty clay loaa, poorly rooted, fev scattsred brown mottles, hard subangular blocky to blocky structur** aany white 1iB* accumulâtions and concr*tiona1 Berging gradually into! (KA) JO—105 ca dry, strong brovn (7.5 ^^ 5/^*) ailty clay loan, few scattered brown aottlas, hard blocky structure, very auch whit* lia*

lia«-nyc*lia| merging intoi

Cca I5O-2OO cm dry, reddish yellow (7.5 YU 6/6) ailty loaa, loose structureless, few gypsum crystals) lying on gravel.

Profile) 42. Date of observation! January 1966. Location) north-vest of Kejla. Elevation) 261 a. Relief! flat. HatWe vegetation» grass and shrubs (scattered, height 30 cm). Parent material! loamy cover on Kiddle Pl«latoc*n« Euphrates terrace. Soil condition«! drV to slightly moist. Field classificationt AoLbc. Soil type1 Typic Caloiorthid. (*, ) 0-3 cm Dry, light yellowish brovn (1O YH 6/4) silt loaa, containing very little organic material, poorly rooted, hard weakly platy structurei merging quickly into! (B) 3-14 cm dry, light yellowish brown (1O YR 6/4) «lit loaa, poorly rootad, «lightly hard crumbly structure» margin« gradually intoi (Kj) 14-40 ca dry to slightly moist, strong brovn (7.5 YH 5/8) silt loam, vary poorly rooted (in cracks), hard subangular blocky structure, many slightly hard whit« lin« concretions) msrging gradually intoi (K.) 40-60 CB slightly moist, strong brovn (7.5 YB 5/8) day loam, very poorly rooted (in cracks), hard angular blocky structur* with slight tendecy to prismatic structure, very few lise accumulation»! merging rather quickly into)

C1c> 6O-I5O cm slightly moist, dark brown ( 7-5 YB 4/4) loam, faintly mottled, bard consistence, structureless, gypsua crystal« in void« and scattered( merging intoi C2cs 15°-200 ca alightly moist, loamy sand to sandy loam, pockets of gypaua crystals or fine-cryatalline filling up of void», mottling Increases «lth depth, less gypsum at 2 a.

127 TABLE 30.5: TYPIC CALCIOHTHIIISi LOAMY OH CLAYEY OF THE BALIKH REGIO».

sasple e U.S.A. PH Eich.ingeabla bases me/100 A C.E.C. in * silt clay 0 * nunber cm gravel 2mm-50|i 50-2u C H C/H CaCOj gypsum Ca «g K Ha Sum me/l 00 i 37-1 0-8 _ 9,8 83,4 6,8 8, 1,11 0,12 9,3 32,6 - 17,9 4,67 3,69 0,09 26,3 26,3 37-n 17-25 3,8 78,1 18,1 8,3 34,0 15.0 6,91 2,14 0,14 24,1 24,1 37-111 42-50 2,9 63,7 33,4 8,4 36,4 11,2 9,96 0,98 0,19 22,3 22,3 37-IÏ 65-75 1.9 61,9 36,2 8,7 36,8 10.1 13.1 0,47 0,37 24,0 24,0

EC 5 water extraot me/lOO g ~5 3 xïo «g 0 ,70 - 0,23 0 ,58 0 ,19 0 .34 0 ,06 1, 17 0,77 tr 0, 76 tr tr 0, 01 1,11 - 0,44 0 .88 0 ,66 0 .22 0 ,27 2, 03 1,76 tr 0, 81 0,41 tr 0, 54 1,52 4 ,02 0,60 0 ,89 1,29 0 .04 0 ,97 3, 19 2,44 tr 0, 71 0,92 tr 0, 81 3,08 3,52 0,62 0 ,55 1,10 0 .01 1.27 2, 93 2,41 tr 0, 76 1,22 tr 0, 43

Chamical and minaralogical analjaas of the clay fraction ( <- 2 SiO SiO 2 2 Clay minerals Sample Sio2 ii2 XgO CaO Ha2O KjO Total number Ho Chi P*~T* K* « P 37 I 61,5 15,6 5,8 3.8 0 ,9 2,5 2,4 92 ,5 6, 7 28, 5 4, 2 Do Chi* P* I*+ K « P 37 II 56,9 16,9 4,7 4.6 0 .8 2,8 2.5 89 ,4 5, 7 32, 7 5,7 Xo Chi P* I** K* 9 P 37 III 57,4 17,1 4,1 5,7 0 ,8 2,6 2,5 90 ,2 5,7 36, 8 6, 4 2, Ho Chi P" I* K* O. P 37 I» 53,3 14,4 8,2 8 ,4 0 ,8 1.7 1,9 88 ,7 6, 3 17, 4 a

Chemical analysas of total soil sample (< 2

Sample HgO CaO

37 I 34,3 7,6 4,7 5,0 20, 4 4,1 1,4 0,1 77 .6 7,7 19,7 2,6 37 II 35,8 6,7 4,9 4,7 20, 5 4,1 1,6 0,1 78 ,4 9,2 19,9 2 ,2 37 III 31,4 6,8 4,6 4,9 20, 6 3,6 1,5 0,1 73,7 7,9 17,4 2,2 37 IY 32,0 7,0 4,6 4,5 19, 2 2,6 1,7 0,1 71 ,7 7.6 19,0 2,4

sample Toiture U.S.A. pH Organic patter Bxchangeble basas me/100 g depth Sample sand eilt clay V C.E.C. number gravel 2mm-5On 5O-2M <2u C/H CaCO, gypsum Kg ma/100 g 0-4 0 ,7 19,8 66,2 14,0 8,3 0,58 0,08 77T 40,5 12,1 3 41 1,86 0,20 17,6 17 ,6 8-II 5-10 1,4 17.0 59,4 23,6 8,4 - 39,7 11,2 3, 44 1,98 0,17 16,8 16 ,8 8-III 13-16 0 14.1 56,2 27,7 8.4 - 41,8 11.3 3, 79 1,56 0,18 16,8 16 ,6 8-IY 25-30 5 13,1 56,4 30,5 8.5 - 42,1 13,2 4, 48 1,18 0,20 19,1 19,1 8-Y 45-50 6,6 15,6 47,1 37,3 8,2 - 42,2 15,0 5.00 0,50 0,46 21,0 21 ,0 8-YI 75-80 7 17,2 42,7 40,1 8,5 - 43,2 9,71 5, 34 0,44 0,51 16,0 16 ,0

1 > 5water extract me/100 g S S. P. cations anions •s Ca Xg K Ha Sum Sum CO3 HCO, Cl SO, HO,

1.14 0,2o 0,51 0,12 0 .09 0T10 0,82 0,73 tr 0,59 tr 0,10 0,04 1,01 0,18 0,50 0,12 0 .09 0,06 0,77 0,63 tr 0,61 tr tr 0,02 1,07 0,15 0,43 0,12 0 ,07 0,08 0,70 0,56 tr 0,55 tr tr 0,01 1,05 0,17 0,42 0,14 0,04 0 ,14 0,74 0,54 tr 0,53 tr tr 0,01 2,19 0,35 0,75 0,27 0 ,01 0 .56 1,59 1,47 tr 0,45 0,25 0,31 0,46 3,19 0,43 0,83 0,29 tr 0,80 1,92 1,89 tr 0,42 0,48 0,31 0,66

128 Profil«t 37. Late of observatioai Hoveaber 1965. Location 1 Hawïje, Balllch valley. Elevatiom 305,3 n. Beliefi f Ut. Istiv* vegetations bushee. Land uset cereale. Parent nateriali Ballkh alluvium- Soil conditional dry. Field clarification! AoLb. Soil typet Typlo Calelorthid.

(A^) 0-15 oa Dry, light yellowieh brown (i0 TB 6/4) silt, containing littla organic material, poorly root*d, oedium bard subangular blocky to crumbly structure; Barging gradually intoi (B) 15 - 32 ca dry, yellowish brown (1O TB 5/6) eilt loan, poorly rooted, nedlua hard subangular blocky structura, lie« accunulationst ••rging gradually intoi (Kj,) 32 - 63 en dry, yellowish brown (10 TB 5/6) «ilty olay loan, poorly root«d, bard blocky structura, lisa concrationai a«rging gradually intoi (KJJ) 63 -100 oa dry, dark yallowiah brown (1O TB 4/4) ailty olay loam, bard blocky atructur«, lisa concretions. Deeper in the profile silty clay loan with fsv mottleai on 250 en blooage on clay.

Profile 1 8. Itate of observation! February 1966. Location1 aast of Mutlaq si Ka'ahiah. Elevation« 299,5 m. Belieft flat. Land uaet carsala. Parant aaterialt loaoy aaterial of fialikh terrace. Soil condition»1 »lightly notât to dry. Soil surface 1 ploughad. Field classification) AoL/Cl b. Soil typet Typic Calciorthid.

(A^) 0 - 4 CB Slightly «oint, strong brown (7.5 TR 5J/6) «lit loam, poorly rooted, containing very littla organic aaterial, «oft crumbly atructure, locally platy atructurej n«rging gradually intot (A..) 4 - 11 ca slightly aoist, strong brown (7.5 TR f>/&) silt loaa, containing vary littla organic oaterial, poorly rooted, eoft crumbly atruotura) oerging gradually intoi (B) 11 - 19 cm »lightly Boist to dry, strong brown (7.5 TB 5/6) silty clay loan, very poorly rooted, soft crumbly to subaogular blocky structura, few line spota) Berging gradually intot (k^) 19 - 41 cm dry, reddish yellow (7.5 TBf5/6) etlty clay loan, vary poorly rooted, hard blocky structure,many llae spota, faw clay- humus «ocuBulatloas; merging gradually intoi

(E21) 41 - 68 cm dry, strong brown (7.5 TR 5/6) silty olay loam, very poorly rooted until 50 on, many clay-humus accumulations, very hard blocky atructure, very auch lime concretions! merging gradually into:

K C 22) 68 - 130 cm dry, atrong brown (7.5 TR 5/6) ailty clay, clay-hunus accumulations, hard blocky structure, few line spots! «erging intoi C, 130 - 150 cm vary dry, light yellowish brown (10 YB 6/4) silty loan) «erging intot C2 ca 1^ ~ 20° c" T*r? dryt ligllt 7*HowiBh brown (iO TR 6/4) silty loam, aottled, few gypsum crystals.

129 sampl« Exchangeable bases me/100 deptb Texture U.S.A. Organic matter Sample C.E.C. sand Bilt * nimber gravai 2no-50n 50-2U C/H CaCO, j./lOO g 93,3 3,9 8,5 0,45 0,05 9,0 28,0 7,15 7,90 1,85 16,9 16,9 - 34-11 15-22 0,8 2,5 82,6 14,9 8,7 - 25, 9 21, 3 10,7 0,17 0,38 32,6 32,6 1,17 34-111 36-40 0 1,7 31,3 67,0 8,7 - 31, 6 16, 0 15,0 0,15 0,85 32,0 32,0 2,66 34-IV 60-65 0 1,2 55,0 43,8 8,5 - 25, 3 0, 02 10, 4 17,7 1,27 1,87 3Î*,2 31,2 5,99 34-ï 85-90 0 4,9 75,5 19,6 8,1 23, 5 0, 02 8, 02 19,8 1,33 2,15 31,3 31,3 6,87

1 i EC EC 5 g J 5 cati ns anio IS xîo 3 x,0 Ca ne X Ha Sum Sun C03 uco, Cl SO MO, 0,20 0,60 0,26 0,05 0,61 1,52 0,74 tr 0.04 - 0 ,18 0, 48 0, 26 0,03 0 ,24 1, 01 0, 75 0,73 tr tr 0,02 - 0 ,36 0, 34 0, 33 0,02 1 ,12 1, 81 1, 86 0,83 1,02 tr 0,01 6, 60 1,28 0, 91 1, 13 0,03 4,87 6, 94 6, 78 0,68 2,69 3,35 0,06 10, 20 4,26 13, 5 8, 81 0,07 10 ,1 32, 5 34, 5 0,27 5i49 28,6 0,10

TABLE 30.6: TYPIC CALCIORTHIDS; LOAMY OVER FRAGKEHTAL OF THE TERRACE REGION. Sample Exchangeable bases ne/100 g C.E.C. depth sample • ilt ne/100 g number gravai 50-2 n 29 I 0-10 27, 2 22,2 59,8 18,0 8, 0 o, 99 0 • 08 12,4 23,4 - 18,5 1,83 1,78 0,22 22, 3 22,3 0,99 44 I 0-10 33 45,5 53,2 1,3 8, 3 0, 80 0 ,11 7,3 22,0 tr 13,6 1,03 1,73 0,09 16, 5 16,5 0,55 44 II 30-40 27 38,2 - - 8, 0 - 10,3 43,7 7,75 0,74 1,81 0,10 10, 4 10,4 0,96 45 I 5-10 25 38,7 57,4 3,9 8, 5 0, 85 0 ,12 7,1 24,0 - 14,3 2,10 1,33 0,18 17, 9 17,a 1,01 46 I f 0-10 2, 5 39,6 54,8 5,6 8, 1 0, 86 0 ,10 8,6 21,8 - 14,2 1,89 0,30 0,27 16, 7 16,7 1,62 46 II* 30-40 25 26,2 49,3 24,5 8, 3 33,4 - 14,1 2,05 0,09 0,27 16, 5 16,5 1,64 47 I * 0-10 17 25,5 60,6 13,9 8, 2 0, 93 0 ,11 8,5 23,9 16,7 1,23 2,74 0,18 20, 9 20,9 0,86

EC. . 5 *ater extrac t me '100 g x 10 cat ions an ions -5 3 Ca K Ha Sum Sum HCO, Cl SO BO «g C03 ,31 1,18 0,17 0,10 0,07 1,52 t,43 0,91 tr 0,49 0, 03 ,27 1,06 0,12 0,18 0,10 1,46 1,39 0,58 tr 0,80 0, 01 ,48 16,2 0,67 0,86 1,68 19,2 18,7 0,21 0,45 18,0 0, 03 ,17 0,59 0,10 0,09 0,18 0,96 0,93 0,92 tr tr 0, 01 ,25 0,76 0,09 0,12 0,09 1,06 1,19 0,64 tr 0,53 0. 02 ,31 1,02 0,12 0,01 0,29 1,44 1,51 0,53 tr 0,91 0, 07 ,27 0,97 0,11 0,26 0,05 1,39 1,26 0,83 tr 0,41 0, 02

TABLE 30-7: TYPIC CALCIORTHIDS; LOAMY OVER SANDY GYPSUM.

sample Texture U.S.A. Exchangeable baeea me/100 g C.E.C, _ , depth pH Organic nattai Sample .* «ilt clay H2° 5O-2ii *.2(i C/N CaCO me/l00 g 6 1*0-10 23,5 61,3 15,2 8,5 0,55 Q07 46,6 19,0 1,30 1,47 0,21 22,0 22,0 6 II* 30-40 23,3 61,5 15,2 8,4 47,7 19,2 1,09 0,72 0,24 21,3 21,3

1 i 5 . ater extra t me/100 g u.s .p. ca ti ons unions 3 x 10 Ca «g K »a Su. Sum co3 HCO3 Cl S04 HOj 0, 96 o, 17 0 ,72 o, 08 o, 07 0,05 0, 92 o, 77 tr 0, 53 tr o, 21 0, 03 1. 12 o, 24 1 .04 0, 09 o, 02 0,07 1, 22 1, 13 tr o,45 tr o, 62 o.06

130 Profil« > U. Dat« of obo«rvationi BOT«ob»r 1965- Location! north of the village Tal •• Sauen. Elevationi 264,5 •• Belief) slightly undulating. Land u««i cereal«. Parent material 1 Balikh alluvium. Soil conditioni dry to «lightly «out, *- Soil surface) ploughed. Piald claa«ification) AoL/Cl be. Soil typet Typie Calciorthid. (i ) 0 - 10 co Dry, yellovinh brown (i0 TH 5/6) silt, containing little organic naterial, poorly rootad, »oft subangular blocky structural narging gradually intot (B) 10 - 28 cm dry, yellowiih brown (1O TR 5/6) ailt loam, containing little organic matarial, poorly rootad, «oft »ubangular bloclcy^ atructur«, f«v lin« accumulâtionaf Berging'gradually intoi

(K2) 28 - 45 c» dry to «lightly aoiat, dark brown (7-5 ™ A/A) clay, vaakly Bottled, yary fa¥ clay-humus accumulation«, poorly rooted, elightly hard eubangular blocky structuf«, fav line accumulation« and concretion«1 «t«rging gradually intot (K ) 45 - 68 cm «lightly aoi«t, dark tiro«n (7-5 *H 4/4) «ilty clay, fov clay-huau« accumulation«, poorly rootad, hard blocky «trueture, li&e concretion«, few pedogenetic gypnun-accumulation«) merging gradually intoi C «S8 - 100 cm «lightly moiat, dark brown (7-5 YR 4/4) «ilt loam, fev clay-humu« accumulation«, hard bloclcy «tructure, «-y«tallin« gypaum aceumula t ion« «

Pr»fil«i 29. Data of obs«rT*tiont Januari 1966.

ElcYationi 276 m. Baliefi high, medium «loping. Kative regetatiom graee. Far*nt material 1 recant aaolic loan underlain by Pleistocene gravel. Soil condition«) dry. Pi«Id classification) C3L. Soil type 1 Typic Calciorthid.

IIC 10 - ca and deeper

Profilet 44. Dat« of obaerratiom March 1965. Location) north of fiaqqa. Elavationt 2^4 m. Rallefi high, medium «loping. Native veg«tationi grass.

Boil conditions) dry to slightly noi«t. Field classification) C3L. Soil typ«1 Typic Calciorthid.

coa platy «tructurat merging gradually intoi (B) 10 -20 cm dry to «lightly moist gravelly silt loan, soft weakly developed crumbly stri

and deeper

Profilei 45. lai« of obeerrationi March 1965.

Parent material! recent aeolic underlain by Pleistocene gravel. Soil conditions! dry.

Soil typet Typic Calciorthid. (A.) 0 - 10 cm Dry silt loam, containing little organic matter, soft weakly developed crumbly structura, upper cms. platy structure; merging gradually intoi (B) 10 - 22 cm dry silt loam, «oft weakly developed crumbly structure, lime mycelia; underlain by)

c* and deeper

131 Sample Texture U.S.A. Organic patter e/100 K C.E:.C. . depth S*Bple sand silt clay nunber gravel 2mn-5Ou 5O-2M <2U C/H gypsun Ca Kg Ha Sum me/1CO g E. S. P. 17-1 10-20 1, 3 16, 0 59, 6 24 ,4 8,6 0,45 0,09 5,0 24,4 22,5 4,07 1,42 0,10 28,1 0,36 17-11 35-45 0 9, 3 52, 0 38,7 8,4 - - - 30,3 25. 5 5,23 0, 72 0 ,28 31 ,7 31 ,7 0,88 17-IH 55-65 0 9,8 63, 6 26 ,6 8,1 - - - 24,5 23, 0 4 ,07 0, 34 0 ,33 27 ,7 27 ,7 1,19 17-Iï 110-115 1, •> S8, 1 _ _ 8,1 - - 4,0 19. 0 45 0, ia 0 ,11 22,7 22 ,7 0,49 5 vatep extract ae/lOO g cations Ca Ka Sus Cl SO, IX. U3 0,71 2,31 0,54 0,07 0,87 3,79 3,17 0,42 0,661,970,12 3,69 0,75 2,14 0,68 0,01 1,04 3,87 3,51 0,46 0,29 2,70 0,06 5,49 2,50 16,4 1,98 0,01 1,73 20,1 19,9 0,31 1,31 18,2 0,12 4,42 2,48 19,3 2,54 0,02 0,99 22,9 21,6 0,22 0,27 21,1 0,02

Sample Texture U.S.A. Organic natter Exchangeable baeos me/100 g depth Sample in silt clay nuabep gravel 5O-2u -.2n C/H CaCO, sypeum Ca Hg .e/100 i 39-1 0-8 1,5 34,9 57,2 7,9 9,0 0,90 0,11 8,2 20,3 19.8 2,04 1,38 0,08 23,3 23,3 0,34 39-11 10-20 2,5 32,1 53,4 14,5 9,1 0,39 0,05 7,8 25,4 17.9 2,22 1,01 0,10 21,2 21,2 0,47 39-111 35-45 5 19,0 48,8 32,2 9,1 35,6 16,0 3,72 0,33 1,02 21,1 21,1 4,83 39-1» 65-70 2,5 19,3 42,3 38,4 8,5 29,9 17,0 5,37 0,23 1,32 23,9 23,9 5,52 39-T 85-95 5 67,3 2,3 57,9 21,0 1,75 0,18 0,05 23,0 23,0 0,22

cation« an ion» Ha Sum Sua C03 HCOj Cl SO HO, 0,13 0,39 0,02 0,04 0,36 0,81 0,00 tr 0,11 0,04 0,16 0,45 tp 0,03 0,36 0, 84 0 ,72 0,61 tp 0,11 tr 5,99 0,78 0,58 0,01 0,01 2,74 3, 34 3 ,16 0,53 1,74 0,75 0,14 11,4 1,85 2,18 0,97 0,01 6,79 9, 95 S,86 0,37 5,74 2,47 0,28 9,48 2,88 20,5 1,77 0,04 3,91 26, 2 24 ,5 0,24 2,25 21,a 0,15

Sample Texture U.S.A. Opganic matter Exchangeable basée ae/lOO g C.E.C. depth Sample Band ollt * number gparel 2aa-5Ou 50-2U C/H CaCO, gypoum Ca Mg me/100 1 40-1 0-8 1, 5 25,7 63,8 10,5 8 ,1 1, 27 0, 13 9.« 17 ,6 21,8 1,53 1 ,86 0,04 25 ,2 25,2 0 40-11 8-14 6 36,6 52,9 10,5 8 ,8 0, 44 0, 07 6 22 ,5 16,5 1,77 1 «32 0,07 19,7 19,7 0 40-111 15-20 6 25,6 61,3 13,1 8,9 - - - 22 ,9 16,5 1,84 1 ,22 0,09 19,7 19,7 0 40-IV 20-30 2, 5 23,5 59,3 17,2 8 ,8 - - - 24 ,5 15,9 2,23 l ,12 0,09 19 ,3 19,3 0,47 40-V 40-50 2, 5 20,2 50,6 29,2 8 ,9 - - - 29 ,1 14,4 3,65 1 ,86 0,10 20 ,0 20,0 0,50 40-ÏI 75-100 1, 5 29,7 8,4 7,9 8,81 15,1 2,91 0 ,18 0,11 18 ,3 18,3 0,60

1 1 5 vater extpact me/100 g cations a lions Ca Mg K >a Sua Sum 00, HCO, Cl so. HO, 0,32 1,23 0,18 0,19 0,11 1,71 1,53 tr 0,75 tr 0,75 0,03 0,17 0,61 0,07 0,07 0,14 0,89 0,64 tp 0,64 tr tp tr 0,18 0,49 0,13 0,05 0,17 0,84 0,56 tr 0,56 tr tr tr 0,18 0,51 0,13 0,04 0,21 0,89 0,56 tr 0,52 tp 0,04 tr 0,33 0,43 0,14 0,02 1,14 1,73 1,59 tr 0,51 0,54 0,42 0,12 6,30 2,85 3,19 0,17 1,31 9,08 13,8 13,1 tp 0,62 8,65 2,79 1,05

132 Profil«i 17.

Dat« of observation* July 1965- Location1 Haartt terrace. El «rat ion 1 249»8 •• Belief! flat to faintly oloping. Land usei irrigated cotton plant« ( 60 cm high). Parent material1 loamy cover on Upper Pleietocene Euphrates terrace. Soil condition«! moist to wet (irrigated 4 day« ago).

Pi«Id classification! AgoLbcr. Soil typei Typio Calciorthid.

(A,, ) 0 - 25 cm Hoist (0-2 cm dry), dark yellowish brown (1O TK 4/4) ailt loan with «one fine gravel, poorly rooted, oontaining black organic material, «oft cruably to granular structure) merging gradually intot (K_) 25- 48 cm noiat to w«t, dark, brown (1O YH 4/4) «ilty clay loam, weakly mottled, «oft cmably to blocky etructur«, poorly rooted,

C 46 - 88 en wet ( on 83 cm groundvater owing to an underlying impermeable layer), dark brown (i0 TB 4/4) silt loam, mottled, soft blocky struoturej merging quickly intot II C- &8 - 113 cm very wet, dark brown (1O ÏR 4/4) «ilty gypsun «and, strongly mottled, conpact consistance.

Profil«1 39-

Date of observation! July 196$. Locationt Haaret terrace. Elevation) £51,2 m. fielieft flat to faintly undulating terrain. Betiv« vegetation! short dry grass and whitish fungi. Parent material! loamy cover on Upper Pleistocene Euphratea terrace. Soil oonditionsi dry. Soil s^ffface 1 a kind of desert pavement is represented by email gravel and stones. Field clasaificationi A OLbc. Soil type! Typio Caloiorthid.

(A ) 0 - 8 cm Dry,very pale brown (i0 TB 7/4) silt loam with some fine gravel, poorly rooted, very little organic material, «oft crumbly «trueture slightly platy no ïir the surface ] merging CT&iluAlly intot (B) 8 - 23 cm dry, very pale brown (1O TB 7/4) silt loam with some fine gravel, containing very little organic aateriil, hard crumbly to granular etrueture, very few lime accumulation»! merging gradually intoi (K ) 23 - 62 cm dry, light yellowish brown (1O TB 6/4) silty clay loam with «orne fin« gravel, hard granular to blocky structure, many

(K ) 62 - 73 cm dry, brown (7-5 TR 5/4) «ilty clay loam with some fine gravel, weakly aottled, hard blocky structure,few lime aocunjulationainerging quickly into: IIC 73 - 106 cm dry, light yellowish brown (1O TB 6/4) gypsum sand with intercalations of cobble and gravel layers, gypsum beard« under the stones.

Profile) 40. Date of observation! June 1965. Location! Hanret terrace, Hamret Balasim. Elevation! 253 m. B«liefi undulating, on the slope of a depression. Dative vegetation) short dry grass, also whitish lichnen. Parent material) loany cover on Upper Pleistocene Euphrates terrace. Soil conditions! dry. Soil ourfacet stones on soil surface. Soil faunat 0-40 cm few worm tracks. Field classification! A lLbc. Soil typei Typic Calciorthid.

(Aj) 0 - 8 cm Cry, light yellowish brown (iO TB 6/4) silt loam with some fine gravel, containing little organic material, well rooted, soft crumbly structure; merging gradually intoi (B) 8 - 14 co dry, very pale brown (1O TB 7/4) silt loam with some fine gravel, »ell rooted, slightly hard crumbly to granular structure» merging gradually intoi (K..) 14 - 23 cm dry, very pale brown (10 SB 7/4) silt loam with some fine gravel, well rooted, hard granular structure) merging gradually intot

(K12) 23 - 31 cm dry, light ycllowUh brown (iO TE 6/4) silt loam with some fine gravel, poorly rooted (aleo old roots with a diameter of 1 cm),slightly bard granular structure) merging gradually into) (K„) 31 - 73 cm dry brownien yellow (10ÏB 6/6) clay loam, locally intercalations of gravel, poorly rooted up to 60 cm, hard subangular blocky structure, aany lime concretions] merging into)

IIC 1C,73 - US CD dry very pale brown (1O TB 8/4) gypsiferous loam, very hard consistence! merging gradually intoi

IIC2 115 - 205 cm dry, yellow (10 YB 7/6) gypsum.

133 Sample Texture U S.A. Or ganic nattar Exchangeable baaes ma/100 g C.E.C. Saaple depth pH in Band silt Clay * * nuober cm graYel 2mm-5Ou 50-2U <.2o SS C C/H CaCOj gypsum Ca Kg K Ka Sum me/l 00 g E.S.P 43-1 0-5 2,5 33,7 64,9 1,4 6,-. 0,63 0,10 6,3 29,5 tr 21,8 0,76 3,01 0,07 25,6 25,6 0,2; 43-11 7-12 1,6 23,3 55.4 21,3 8,6 30,8 22,6 1,01 1,91 0,15 25 ,9 25,9 0,58 43-111 20-30 2,8 20,4 51,1 28,5 8,4 - 32,4 24,0 1,16 0,48 0,29 25 ,9 25,9 1,12 43-IV 50-60 4 17,1 42,0 40,9 8,4 28,5 19,8 1,20 0,29 0,42 21 ,7 21,7 1,94 43-v 70-80 0 31,7 8,1 - 6,4 6C,6 18,5 0,30 0,15 0,05 19 • 0 19,0 0,26

cations «mon« X^O^ ">3 C. Mg K lia Sum Sum C0, HCO. Cl SO Ho.

0,36 1,93 0,05 0,09 0,08 2,15 1,95 1,46 0,17 0,98 0,02 0,02 0,10 1,12 0 ,94 tr 0,50 tr 0, 44 tr 0,24 0,96 0,05 tr 0,27 1,28 1 ,31 tr 0,46 0!,25 0, 45 0, 15 2|38 0,49 1,65 0,19 tr 0,78 2,62 2 ,64 tr 0,40 0,,29 1, 62 0, 33 2,90 2,24 17,1 0,17 0,01 0,34 17,6 18 ,0 tr 0,16 0,,25 17, 4 0, 15

TABLE 30.6: TYPIC GYPSIORTHIDS.

Sample Texture U.S.A. pH Organic natter Exchangeable baaea ma/lOO g depth B Sample in Band silt clay 2° number 'aval 2 mm-50li 50-2(i *.2u C/H CaCO, gypsum «g ie/100 i

30-1 0-5 116 26,7 60 ,7 4,6 3 0, 31,4 0,31 3,79 0,14 22,3 22,3 30-11 8-13 2 23,9 66 ,0 10,0 8, 3 - 34,2 tr 13,7 0,68 3,41 0,23 18,2 18,2 3O-III 20-30 1, 4 20,7 67 ,6 11,7 8, 1 35,5 0,20 11,8 1,38 2,82 0,39 16,4 16,4 30-IV 35-45 0, 8 45,8 8, 3 - 15,8 53,0 5,S7 0,o4 0,42 0,04 7,17 7,17 30-V 55-65 0, 8 59,0 8, 6 - 4,7 65,4 4,69 0,76 0,27 0,09 5,81 5,81 30-VI 80-90 0 55,7 8, •> - 7,0 55,0 4,67 1,28 0,39 0,19 6,53 6,53 1 I 5 water extract ne/100 g ECe X 10-" «g 0,63 2,72 0,56 1,86 0,06 0,19 0,67 2,78 3 ,15 tr 0,48 0,25 2.37 0,,05 1,26 8,60 1,14 3 ,10 0,27 0,25 2,29 5,91 6 ,03 tr 0,39 2,54 2,31 Oi,79 2,38 6,80 2,12 9,22 1,83 0,23 2,49 13,8 13 ,3 tr 0,29 2,35 9,60 o,,84 0,56 6,40 3,74 17 ,7 2,45 0,09 2,09 22,3 22 ,0 tr 0,16 1.72 19,5 0,.65 1,55 6,40 2,66 17 ,7 3,38 0,05 3,05 24,2 24 ,5 tr 0,11 2,50 21,1 0,,81 2,91 6,00 3,48 18 ,7 6,08 0,06 5,11 30,0 29 ,7 tr 0,16 4,66 23,3 1,,60

Chemical and mineralogical analyses of the clay fraction (< 2M) • Sample number SiO, MgO CaO Ha 0 Total Clay »inerals

30 I 54,4 17,3 4,3 4,9 0,4 1,8 2,4 65,4 5,4 33,6 6,3 Chi K « P 30 II 55,6 15,8 8,2 5,7 0,5 0,4 2,3 88,5 6,0 18,2 3,0 Chi It 0. T 30 III 52,1 15,1 6,6 4,7 0,6 0,5 2,2 81,8 5,9 21,2 3,6 Chi K

Chemical analyses of total soil sample (t 2 mm )t

Sample number CaO KnO2 Total 30 I "•2° 45,4 7,3 478^ 4,4 17,2 ~3"7

134 Profilât 43. Data of observation! February 1966. Location1 vaat of Hai'zila. SI«Tition1 292,5 n. Belief! flat. Hâtive Tagatatiom short graeeee (acattered). Parant nuitariali valley fill in Lower Pleistocene proluvial gypsua dapoaita. Soil condition»1 dry to slightly nolat. Field clasaifieation» agOlb. Soil typai T^pic Calciorthid.

(A1) 0 - 10 en Slightly »oist, etrong brown (7-5 ÏH 5/6) silt loao, containing little organic material, rooted, crumbly atruotura, locally a slightly hard platy atruotura at tha aurfaca; margin« gradually intoi (B) 10 - 15 en •lightly aoiat to dry, atrong brown (7-5 TH 5/6) ailt loan, containing vary little organic Batarial, rooted, elightly hard to hard crumbly structura, very fa« line accumulation«! merging quickly intoi (Kg) 15 - 40 CB drj, atrong brown ( 7.5 ÏH 5/8) clay loan, poorly rooted, elightly hard to hard subangular blocky atructure, Tery much aoft vhitish 1ime accuBulat iona 1 Barging ^^adually into 1 (K-) 40 - 70 ca dry to slightly moiat, atrong brown (7.^ TB 5/8) silty clay, vary poorly rootad, hard angular blocky atructure, aany lisa accumulation» from 40 to 60 cm, number of lima accumulation» decreaaing from 60 to 70 CB| merging quickly intoi IICc» '° ~ 10° CB Doist' T*r*r P*1* brown (10 ÏS 7/4) gypaum powder, mottled, alightly hard conaiatance. Down to 150 cat gypaumpowder becoaaa mora mottled, loam contant ia increaaing dovnwarda.

Profilai 30.

Data of obeervatiom February 1966. Location1 eouth-south weat of Herjan. EleTatiom 294 a. Beliafi flat to faintly eloping. Bative vegetation) short grasses scattered. Parent material! Lover Pleietocene proluTial gypauo depoaita. Soil conditional dry to slightly nolet. Field claaaificatiom C (b)r. Soil type 1 Typic Oypaiorthid.

(*n) 0 - 5 ca Dry, yellow (1O TB 7/6) silt loam with a orne fine grarel, containing little organic material, rooted, alightly hard platy structure, merging quickly intoi

(a]2) 5 - '5 cat ^J to alightly moist, redaish yellow (7.3 TB 6/6) silt loan with aoae gravel, containing very little organic Batarial, rootad, alightly hard crumbly structure, vary few lime eccumuletionsf merging gradually intot (K) 15 - 30 ca dry, atrong brown (7.5 TB 5/8) gypaifarous silt loam with some fine gravel, rooted to poorly rooted, hard aubangular blocky structure, line concretions) merging gradually intot

II Cf 30 - 45 OB dry, yellow (1O TB 7/6) loamy gypaua aand, poorly rooted, tendency to hard angular blocky structure, mottling) merging gradually intoi

II C2o> 45 - 70 ca dry to alightly moiet, reddiah yellow (7.5 TB 7/6) gypaun aand, hard consistence, etructureleaa but cemented, mottling) aerging quickly intoi

II C^s 70 - 90 em coarse gypaua sand with clay, hard conaiatance, caaantad.

135 T«xtur« U.S.A. Organic nattar Exchangaabla tel aa aa/lOO g C.S.C. pH Saapla daptn la * aand allt clajr H-O * mtabar CD ! 2BD-50M 50—2M *2P 1Î5 C S C/H CaCO, gypnua Ca •g K la SUB oa/lOO g S.S.P. 10-1 1-6 0 1.5 90,1 8,4 8,1 1,29 0, 16 8,1 18,8 0,19 34,8 0,27 1 ,65 0,40 37,1 37,1 1,08 fl 10-11 30-35 0 55,5 .° 6.9 47,6 12,4 0,25 0,48 0,22 13,4 '3,4 1,64

1 t 5 vatar •xtraot ma/100 g

EC( BC oationa tni ons Sua C0 ICO, Cl Ca »g K Ba Sun 3 »4 •°3 2,22 0,72 3,82 0,09 0,09 0,07 4,07 4,02 tr 2,84 2,22 18,9 0,31 0,09 0,06 19,4 18,9 tr 0,23 0, 25 18, 3 0,16

3*apl« Taxtura U.S.A. pH Org.uil 0 »attar Exohaagaabla tea a .a/100 g C.I.C. Sampl« dapth la •and »Ht cl*/ i * * auabar CD grave 2aa-5Ou 5O-2u <.2n 1 ' 5 C B C/B CaCO, orpaua Ca >g « Ia Sua •a/100 g E.S.P. 12-1 0-5 o 23,9 7,7 1,49 0. t7 8,8 20,9 10,1 23,3 1,06 2 42 0,31 27,1 27.1 1,14 12-11 15-20 0 44,2 8,0 5,4 62,5 11,1 0,79 0 31 0,16 12,4 12,4 1,29

1 i 5 vatar axtraot na/lOO g EC^ cationa DB HCO Cl H Ca Kg E Sa Sun Sum C03 3 »4 °3 2,86 2,30 16,2 0 39 0,35 0,08 17,0 16,5 tr 0»47 tr 15.7 0,33 3,80 2.32 18,6 0 42 0,10 0,25 19.4 19,1 tr 0 21 0, 25 18,0 0,67

Saapla Taxtiira U.S.A. pH Orgimie mattar Sïoha abl a »aa*a na/lOO g C.E.C. Saapla daptn in % aaod allt el i CD 2nu-5Ot 50-2M -2 1 V C B C/B G rp*UB c H« K .a Sua »a/100 g

13-1 O-5 0 18,5 7,8 0,66 0,10 6,6 20,9 37,5 16,2 tr 1 15 0,18 17,5 17,5 13-11 25-3O 0 46,6 8,1 - - - 8,0 74,9 2,23 0 23 1 54 0,17 4.17 4,17 13-III 60-65 0 45.6 8,2 13,7 71 ,6 5,47 1 34 0 18 0,16 7,15 7,15 J3-IT 100-110 0 56,5 8,1 - - -

1^- «at« r axtract na/lOO g E.S.P. BC 3C # ca tlo aa ani< na 3 SUM x 10 t a M« K Ba ïum co3 HCO. Cl "4 *°3 1,03 2,78 ï,26 17 .5 0,24 0 ,22 0,06 16,0 1 ,6 tr 0,36 0,25 16 ,9 0,05 4,08 4,80 ?.42 19,0 0,86 0 ,10 0,47 20,4 20,4 tr 0,17 tr 19,4 0,64 2,24 5,26 Î.58 18 ,2 2,08 0 ,90 0,79 20,0 2 ,4 tr 0,16 0,60 19 ,7 0,90 1,74 6,20 Ï,18 18 ,1 3,77 0 .10 W» 2 ,6 2 .6 tr 0,13 1,10 20 ,1 2,23

TABLE 30.9: TYPIC CAMBOBTHIDS OF THE VOLCAHO REGION.

Taxtura U.S.A. Organic nattar Exebangaabla teaaa ma/100 g C.B.C. »-PI. aaod .lit &uab«r 2a«-5O» 50-2P C/B CaCO. Ca •a/100 « 41-1 0-6 2,5 55,9 31,9 12,2 8,7 0,10 0,02 57Ô 19,1 tr^ 13,2 3,92 0,4è 7728" 24P? 24.9 41-11 6-17 3,5 65,8 27,7 6,5 9,5 0,22 0,03 7,0 13,4 - 18,2 1,15 2,89 0,36 22,6 22,6 41-111 30-40 8 62,5 27,0 10,5 9,2 15,5 - 19,7 2,03 2,53 0,72 25,0 25,0 41 -n 70-80 26,5 70,3 24,5 5,2 8,8 13,5 - 17,8 1,76 0,27 4,31 24,1 24,1 41-T 95-105 22,5 88,4 7,7 3,9 8,4 6,8 tr 13,3 0,20 0,52 4,55 18,6 18,6 41-VI 120-130 9 90,5 8,2 1,3 8,7 3,8 tr 6,3 2,97 0,18 2,37 11,8 11,8 41-TII 165-185 5,5 '63,4 30,0 6,6 6,2 20,9 tr 16,2 3,47 0,4a 6,19 26,3 26,3

axtract ma/100 g

29,2 17 3 2,41 2,72 0,43 0,01 10 8 13,9 13,2 tr 0 38 3,03 9,51 0,27 1,59 - 0,16 0,22 0,02 0,06 0 51 0,61 0,68 tr 0, 67 tr tr 0,01 2,88 - 0,20 0,26 0,03 0,03 0 66 1,00 0,93 tr 0, 57 0,32 tr O,C4 17,9 14 8 1,09 0,93 0,14 tr 4 48 5,55 5,56 tr 0, 37 4,86 tr 0,33 24,5 12, 9 2.39 6,02 0,24 0,01 5 33 11,6 11,4 tr 0, 23 3,53 7,52 0,11 20,1 12 2 1,66 4,16 0,22 0,01 5 04 9,43 8,75 tr 0, 24 3,06 5,41 0,02 23,5 23 5 4,19 14,6 1,59 0,02 10 8 27,0 28,6 tr 0, 22 4,59 23,7 0,09

136 Profilai 10. tat» of obaamtioni Pabruary 19*6. l^oatiom Chunay*. KlaTationi 315.5 •• Baliaft faintly «lopin«. latiTa ragatatiom grasa. Parant salarial! Lovar Plaiatooana proluri»l gypaun dapoaita. Soil conditional dry. Soll aurfacai fa« gjpaua polygon««) aiero-dunaa with drlad graaal lovar part« of tta» «oil aurfaca bar* aora aoiat and graan graaa. holaa of foxaa, Bolaa and nie». Plaid claaaifieatloni C . Soil typai Trpio Oypaiorthid. (a ) 0 - 12 » Dry, yallowlah brovn (iO TB 5/4) »lit, containing organic aatarial, H«11 rootad, «oft cruobly atruotur*) Margins rathar abruptly intoi II C 12 - 64 em dry, raddiah yallov (7.5 TB 7/6) gypaua aand, poorly rootad down to 33 o«, «lightly bard atructuralaaa, lanaas of Tartical gypsua cryatalal lying on nard cryatalllna gypaua.

Profilai 12. Data of obaarntlom Pabruary 1966. Location! Cbunaya, ElaTationt 324 •• Bali*f1 faintly «loping. latixa vagatatlom grasa. Pmrant natarlali Lo«ar Plaiatoeana proluTial gypaua dapoalta. Soil aurfacai polygonal atruoturaa of gypaunl aooa bolta aada by iniuli. Soil conditional dry. Plaid elaaaificationi C . Soil typai Typio Ojrpalarthid.

(*,,) 0 - S OH Dry, light yallovlan brovn (iO TB 6/4) gypaifaroua silt, containing vary llttla organic utarial, poorly rootad, aoft pl«tj atruoturai Barging intoi

II C1 5 - 25 ci dry, vary pal* brovn (10 TB 7/4) fina tazturad gypaua a«nd, «lightly bard •tructuralaaal nrglng Intoi 'II C. 25-30 cat dry, «hit« gypaua «*nd «isad with gypaun powdar and gypaua cryatala, baxd caoantad layar, gjpaua cry« tal a foraad »* naadlaa or bladaa) aarging trragularly Into a layar vitb bard gypaum oryatala.

Profilai 13- t»t« of obsarratiom Ntaruary 1966. Location) Cbunaya. Slavationi 315 a. Raliaft soft »loping tarrain. lativa vagatatloni graaa. Parant amtariali Loa«r Plalatooatta proluvlal gypaua dapoalta. Soil aurfftcai sull dunaa and fox bol««. Soll condition»! »lightly aoiat to dry. Plaid olaaaifleatlom C cr. Soil typai Typio dypalortbld.

(A}) 0 - 15 ca Slightly aoiat, light yalloviab brovn (10 TB 6/4) «iltj loaa, aoft vaakly davalopad cruablj atruotura, 0-10 ca vail rootad, IO-15 cm poorly rootad) aarging gradually intoi II C 13 - 4$ ca dry, ft? pala brovn (iO TB 6/4) grpaua povdar Bijcad vltb loaa and clay block«, allgbtly b*rd atructuralaul Barging gradually intoi

II Cg 45 - 90 ca dry, jrallov (10 TB 7/6) fina taxturad gypaua aand aixad vitb powdar and fa« cl*y pabblaa, aottlad in tb« o lay pabblaa, •lightljr baxd atrueturalaaai aarging Into) II C^ 90 - 150 OB dry, light OUT« gray (5 T 6/2) clay balla tilth gypaua eryatali, iron coatings »round o lay pabblaa, bard oonalatancai Barging abruptly intoi

II C4 130 - 160 ca dry, light ollra gray (5 T 6/2) aixtura of clay with gypaua crystal«. Profilai 41. Data of obaarrationi Juna 1965. Location! Volcano region (Jabal Mankfaar Onarbi). Bl«f»tioni 255,8 a. Bali.ft undulating. latin T*g*tatlont abort graaa and aorghua (acattar*d). Parant aatariali Qppar Plaiatocana to Boiocana lapilli. Soil oonditlanat «lightly aoiat to dry. Soil eurfacai undolatlng, lapilli on nafaoa. Plaid claaalfloatlom A21L. Soil typ. 1 typio Caabortbid.

(*.,) 0 - 6 «a Slightly aoiat to dry, pala brovn (iO TB 6/3) a*ndy loaa,( loaa with lapilli), containing vary littla organic MAtaria.1, vail rootad, «oft to «ligbtlj consiatanaa, tandancy to blocky atructurai Mrging gradually intoi (B.,) 6 - 17 oa «lightly aolat, p*la brovn (iO TR 6/3) »andy loaa,(loaa vlth lapilli), vail rootad, «lightly bard eonaiatanca, tandancy to block? atruoturai aarging gradually intoi

(B2) 17 - 54 ca «lightly aoiat, light yalloviah brovn (iO TB 6/4) a*ndy loan (lapilli loaa), poorly rootad, aoft oonaiatanea, tandancy to blockj atruaturai aarglng abruptly intoi C, 54 - 92 oa «lightly aolat, light yalloviah brovn (iO TB 6/4) aandy lo*a,( loaay lapilli), poorly rooted up to 72 cm, loose atrueturalaaa; «arging Tary abruptly intoi IICj • 92 - »15 OB dry, grey (2.5 T 5/0) lapilli aand, loo,, atruoturalaaa, aarging abruptly tntoi

IIC3 115 - 150 ca dry, grey (2.5 T 5/0) »and,(fina taxturad lapilli), Barging Intoi

tIC4 150 - 165 G" «liçhtly aoiat, light yallowiah brovn (tO TB 6/4) aandy lo«,(lapilli loa»)( blocag* oa 185 «•-

137 TABLE 30.10: TYPIC SALORTHIDS OP THE VOLCANO REGIOH.

Sampla Organic matter Ezcbangaabl« baaaa oe/lOO g C.E.C. Textur« U.S.A.. pH sand alit clay * grarel 2n»-5On 5O-2M *.2u 1?5 C I C/H CaCO Ca Sus »•/IOO g 16-1 0-4 2,5 55,1 38 ,4 6,5 », 1 0,38 0,06 6,3 10,4 13,5 tr 4,17 4,45 22,1 22,1 16-11 20-30 7,5 44,4 54 ,3 1,3 8, 9 16,3 21,5 0,85 2,65 0,99 26,0 26,0 16-11I 60-70 36,5 47,7 47 ,0 5,3 9, 0 19,8 12,9 2,71 1,36 12,9 29,9 29,9 16-IT 145-155 17,5 14,4 81 ,5 4,1 9, 4 3,0 2,72 0,70 0,67 1,52 5,61 5,61

1 Q water extract me/100 g

20,1 63 ,0 4,52 3,04 tr 0,68 19,5 23,2 22,7 tr 0,46 11 • 9 5,85 4,45 3,81 64 ,3 4,52 2, 04 0, 02 0,15 20,1 22 ,3 22,5 tr 0,40 12 ,5 6,22 3,34 43,1 22 ,6 2,20 2, 20 0, 17 0,03 9,43 11 ,8 11,2 tp 0,70 6 ,04 1 ,84 2,60 27,1 6,89 0,61 0, 53 0, 11 0,04 2,16 2,84 2,83 tp 0,48 0,79 1 ,34 0,22

Caeaical and mineraloglcal analysas of ta« olay fraction (<.2(i)t

Sample Al SiO? SiO? 2°3 nu. bar SiO Pa «80 CaO 0 Total A12O3 Pa Clajr Xlnarale 2 "2 °3 2°3 "•2 *2 3 2°3 16 I 49,6 14 ,3 9,0 5,3 0,7 2 • 9 2,8 84,6 5,9 U,8 2 • 5 «o* Chi p I" K* Q P 16 II 51,3 14 ,2 9 ,0 6,1 0,6 1,9 2,7 85,8 6,2 15.3 2 ,5 ».* obi p* I» I* D P I« 16 III 51,6 14 ,6 8 ,3 5,8 0,4 2 ,6 2,5 85,8 6,0 16,9 2 ,8 »0* Cbl P* I* Q P 16 IV 57,0 7,3 6 ,7 3,2 3,0 11 ,0 1,8 89,0 13,3 22,8 1,7 Xo Chi P* I* IC* Q P

Chemical analyses of total soi! tupi« (<.2 ma )i

al Sampla 310, S10? „0 nuaber sio XgO CaO Ha Total 2 "2°3 *2°3 2° V «=o2 ÂV 1 **2 f» 2o, 16 I 34,5 5,6 10,2 12,4 10,7 6 ,3 1,4 0,2 81,3 10, b 9,1 0 ,9 16 II 38,3 5,4 9,5 12,0 12,3 7,2 1,3 0,2 86,2 12, 3 10 ,8 0 ,9 16 III 36,2 6,3 10(2 11,6 12,0 6 ,8 1,2 0,2 84,5 9,9 9,6 1,0

138 Profil»i 16. Date of obnmtioni May 1965- Location» Volcano region. Elevation) 262,2 n. Beliefi undulating. Kative vsgetatiom dry grass. Paraat materiali Upper Pleistocene to Bolocene Tolcanio lapilli mixed with loam. Soil conditionst dry. Soil surfacei much lapilli on surface (finir matarial bas been blown out). Field olassificatiom A2L1 . Soil typei Typic Salorthid.

(At)M 0 - 4 on Dry, pale brown (10 TB 6/3) sandy loan (loan; ooaree textured lapilli), poorly rooted, -nrj little organio Material, soft platy struoture) merging gradually intoi (B) 4 - 48 en dry, pals brown ( 10 IB 6/3) eilt loam,(loamy coarse textured lapilli), poorly rooted, soft consistenoe, few weakly eenented aggregate»! merging abruptly intoi C 46 - 110 on dry, light yellowish brown (i0 TB 6/4) candy loam, (coarse textured lapilli with loamy adnixture), poorly rooted up to 55 ca, soft consistence, rmxy few weakly cemented aggregates; merging abruptly intot II C 110 - 135 on dry, light yellowish brown (10 YH 6/4( brown due to a kind of loam coating ) or grey (2.5 Y 5/0) :©o*r«e textured lapilli, soft oonsistsnee, atructurelese) merging abruptly intot II C_ 135 - 145 CB dry, grey (2.5 T 5/0J fins textured lapilli, soft oonsistencei merging abruptly intot II C 145 - 155 en extremely dry, grey (2-5 I 5/0) lapilli, soft consistence. Profilet 46.* Date of observation! January 1966. Location! west of Hlsiban. SlsTatiom 304 n. Reliefi flat, top. Satire vegetationt grass. Parent naterialt recent aeolic loaa underlain by Pleistoosne gravel. Soil conditional dry. Field olassificationt C2L. Soil type 1 Typic Calciorthid.

(a_) 0 - 10 en Dry strong brown (7.5 YB 5/8) silt loan, containing little organic matter, soft weakly deTOloped crumbly structure, upper cas soft platy structure» merging gradually intoi (B) 10 - 20 cm dry strong brown silt loan, soft weakly developed crumbly structure) underlain byi I1C 20 * 60 CB loany sksletal, rapidly norging into fragmentai ^^avel with line accumulations. °* and despar

Profilet 47.*

Date of obserrationi January 1966. Location1 east of Shininah. Elevation1 308 a. Belieft flat, top. Hative vegetation! grass. Parent material! recent aeolio loam underlain by Pleistocene gravel. Soil conditions! dry. Field classification1 C3L. Soil typet Typio Calciorthid. (a_) 0 - 10 en Drj gravelly silt loan, containing little organio natter, soft weakly developed crumbly structura, upper cms platy structure) merging gradually intot (B) 10 20 cm dry gravelly ailt loan, soft weakly developed cruably structure) underlain byi 20 — 60 ca gravel cemented by line.

Profile 1 6.* Date of obserrationi February 1?66. Location) south of Hadi al Himar. Elevation! 344 •• Belief! flat, valley bottom. Land uset barley. Parent material! loamy valley fill. Soil conditions! dry to slightly aoiet. Field classification! Ag. Soil typei Typie Calciorthid.

(Af) 0 - 10 en Slightly Boist silt loam, containing little organio material, soft crumbly structure, the upper cms bave a platy (K) 10 - 60 cm slightly molat (until 40 en) silt loam containing some gravel, subangular blockjr structure, white line spots 1 IIC 60 - 110 OB dry structureless gypsum sand) bloeags on hard gypsun underlain by limestone.

For aoil analyses one is reffered to tables 30.6 and 3O.7. 139 b. Clay minerals as related to average values of oxides in the fraction < 2 n.

On comparing the content of palygorskite, illite and montmorillonite with chemical data of the fraction <2 p,, we found a direct correlation with the content of MgO, K„O and CaO. This is indicated in table 31.

Table 31. Content of palygorskite, illite and montmorillonite as related to that of M O, KO and CaO in the fraction < 2 p,

average average average % Palygorskite %M O % illite %K2O % montmorilonite %CaO g 0-10 1,2 10-30 1,9 0-10 0,6 10-30 4,5 30-50 2,4 10-30 1,1 30-50 8 50-75 4,0

B. Classification of soils.

Soil development has taken place in the surface layers of nearly the whole area. There are only a few outcrops of bare rocks not supporting even a poor vegetation of grasses. These outcrops are: —the lava flows from the volcano Mankhar Gharbi; the surface is covered by basalt blocks and aeolic loam occurs only locally to a maximum depth of 20 cm; —the Miocene limestone east of Hawije; the surface is covered with limestone blocks and locally there are encrustations and/or accumulations of a few centimeters of loam.

1. SOIL CLASSIFICATION CRITERIA

Soil classification criteria of the "Soil Classification, A comprehensive system, 7th Approximation" and supplements (U.S. Dep. of Agric. 1960-1967) were applied to soils of the Balikh Basin. A subdivision of subgroups into families was made with the aid of differences in texture and mineralogy. Not all properties given in the 7th Approximation and supplements a.o. for calcic horizons and cambic horizons are well marked in soils of the Balikh 140 Basin and completion was necessary for highly gipsiferous soils. Therefore, the following diagnostic characteristics were selected: Calcic horizon—A horizon that is more than 15 cm thick, has a calcium carbonate percentage of more than 15 percent and has more than 5 percent by volume of secondary carbonate in concretions or soft powdery forms. It is found to be identical to the (Kg) horizon. Cambic horizon—This is a horizon which shows evidence of removal of carbonates and consequently has less carbonates than the underlying calcic horizon. It has soil structure rather than rock structure and contains some weatherable minerals. Ithas atexture finer than loamy fine sand in the fine earth fraction and its base is at least 25 cm below the soil surface. Therefore, a cambic horizon which is not thick enough is regarded as not diagnostic although it is indicated as (B). Mottling is less pronounced and this term refers in this text to spots with, brown and strongly brown colours different from the soil matrix. Highly gypsiferous soils are found to have a different genesis as compared with highly calcareous soils. Therefore, a new great group of Orthids was defined and indicated as Gypsiortids having a gypsum content of more than 25 percent by weight in all parts of soil after the upper 30 cm or less are mixed. These soils are often characterized by the occurrence of an indurated gypsic horizon, that is a petrogypsic horizon with or without gypsum polygones. A petrogypsic horizon contains more than 50 percent gypsum and is usually thicker than 10 cm. The induration is caused either by dehydration of gypsum and subsequent hardening after wetting, or by solution and redistribution followed by recrystallisation of gypsum into massif plates. It is not or difficult to penetrate by spade or auger when dry and is impermeable to roots. The hardness is 2 according to Mohs scale of hardness. Gypsum polygones are vertical encrusted powdery or crystalline gypsum plates.

2. DESCRIPTION AND CLASSIFICATION OF SOILS ACCORDING TO THE 7th APPROXIMATION WITH SUPPLEMENTS.

Soils of the Balikh Basin are characterised by the occurrence of an ochric epipedon. The percentage of carbon in the upper 10 cm is often higher than 0,58 percent but drops rapidly below this depth to 0, 30 percent or less. The upper 4 cm are generally crusty. The soils are classified as Entisols and Aridi-

141 sols. For complete definitions of orders, suborders, great groups and subgroups one is referred to the "Soil Classification, A comprehensive system, 7th Ap- proximation" and supplements. Only properties of the soil profile regarded as most characteristic in the region are given below. a. Entisols of the Balikh Basin.

Mineral soils that have no diagnostic horizon other than an ochric epipedon. a.l. Fluvents. Entisols that 1. have textures of loamy very fine sand or finer; 2. have an organic matter content that decreases irregularly with depth or remains above 0, 35 percent (0, 2 percent carbon). Thin strata of sand may have less organic matter if the finer sediments at 1, 25 m or below have 0, 35 percent or more; 3. are not permanently saturated with water; 4. have a mean annual soil temperature of more than 0°C. a.l. 1. Torrifluvents . Fluvents that 1. have a mean annual soil temperature of more than 8 C and a mean summer soil temperature at a depth of 50 cm of more than 15°C (chapter I, B,3); 2. are usually dry in most years in all parts of the soil between 18 and 50 cm. a.1.1.1. Typic Torrifluvents (table 30.1: profiles 20 and 52). Torrifluvents that are not Vertic or Durorthidic. The greater part of soils lying on the Euphrates lowest terrace belongs to this subgroup. The soils are classified into three families according to differences in texture. These are loamy, clayey and loamy over sandy. Salinity is generally low, but strongly saline soils due to irrigation activity are found locally e.g. profile 52. This profile is classified as aTypicTorri- fluvent (loamy) and has an EC inthetopsoil of 26,0. Comparison of the composition of cations and anions in the 1:5 water extract reveals the occurrence of

142 NaCl and CaSO4< Locally at the foot of the terrace escarpments, salts were accumulated by drainage water, resulting in a weakly to moderately saline soil. The soil profile nr. 20 was classified as a Typic Torrifluvent (loamy). The mineralogical assemblage of this profile is fairly uniform despite the sedimentary variation in grain size. This is shown also by the silica/alumina ratios of the total soil sample, which are only slightly lower in samples 20 II and IV with a low content of sand. Quartz, chalcedony, acid plagioclase andmuscovitearethe dominant minerals of sand and coarse silt fraction while montmorillonite is the most abundant mineral of the clay fraction. Easy weatherable minerals are still present. Opaline silica occurred in a relatively high percentage of the sand fraction showing a certain degree of mobility of silica in being taken up by plants. There is only a weakly developed structure while the sedimentary platy fabric is still present. Some mottling occurs in subsoil and deeper subsoil, but there is no significant iron illuviation. Chemical reaction is alkaline with a pH of 8,4. The adsorption complex is highly saturated with calcium and magnesium as dominant cations. The organic matter content is low and decreases irregularly with depth. The C/N ratio is narrow, the organic matter being in a well mineralized condition. The percentage of carbon depends on texture. A silty clay at a depth of 185 cm was found to have 0, 33 % carbon while a sandy loam at a depth of 75 cm had only 0, 05 % carbon. However, generally the content of carbon remains above 0,2 percent. EC and E.S.P. values of profile 20 are small and salts or alkali do not effect plant growth. Leaching of silica and alumina is nil, the silica/alumina ratio slightly increases upwards in the soil profile. Comparison of the chemical data from the fraction <2 p, with those of Typic Calciorthids shows a higher content of CaO (Mo ) and a smaller percentage of + K2O(I ). Some sodium accumulated in the subsoil, but there is a general trend of accumulation of sodium and potassium in the topsoil owing to an upwards movement of easy soluble ions with the evaporating water. Most of these ions have been derived from the salt containing irrigation water. The silica/alumina ratios are high due to the high content of montmorillonite and the contribution of palygorskite. 143 a.1.2. Ustifluvents . Fluvents that 1. have a mean annual soil temperature of more than 8°C and a mean summer soil temperature at a depth of 50 cm of more than 15 C ( chapter I, B,3); 2. are usually moist but are dry for 90 cumulative days or more inmost years in some subhorizon between 18 and 50 cm but are not continuous- ly dry in all subhorizons between these depths for as long as 60 conse- cutive days in more than 7 out of 10 years.

a.1.2.1. Typic Us tif luvents (table 30. 2: profile 7). Ustifluvents that lack the properties as defined for the Vertic Usti- fluvents described in a. 1.2.2. These soils are found in the Balikh and Euphrates valley e.g. the flood plains of Nahr Balikh and Wadi al Kheder, and north of Hazimah at the confluence of former and recent course of the Balikh. The soils are classified into 2 families according to differences in texture. These are loamy and clayey. Loamy soils are found where the Balikh takes its course through the Holo- cene Euphrates terrace. The greater part of soils have a clayey texture, are mottled, highly calcareous and the adsorption complex is highly saturated with calcium and magnesium (see profile 7).

a.1.2.2. Vertic Ustifluvents (table 30.3: profiles 15, 19, 27 and 51). Ustifluvents that differ from the Typic in having a. cracks at some period inmost years that are 1 cm wide at a depth of 50 cm, that are at least 30 cm long in some part, and that extend upward to the surface or to the base of an (A^ horizon; b. more than 35 percent of clay in horizons that total more than 50 cm in thickness within the control section.

Some other characteristics found in these soils are; — Gilgai is absent or very weakly developed; — the content of swelling clays is only 5-10 percent of total soil; — slickensides are small and merely stress faces, and intersecting slickensides are not observed; 144 — parallelepiped structural aggregates are small and weakly developed.

The soils have a fine clayey texture and an ochric epipedon. Soil structure is weakly developed while a sedimentary platy fabric is still present. It has a low stability and is destructedby thoroughly wetting. Only in profile 27 being relatively dry for some period has a pronounced soil structure developed. The minéralogie assemblage is fairly uniform although sedimentary variations occur, niite, palygorskite, quartz, albite and orthoclase are the dominant minerals. The minéralogie al and chemical composition of the fine silt fraction 5-10 p, does not differ very much from that of the clay fraction < 2 p,, only chlorite is more abundant in the fine silt fraction. The topsoil has a higher content of illite and a lower content of palygorskite as compared with the underlying layers.. The silica/alumina ratios of the clay fractions are about 5,5. The ratio of the upper topsoil is slightly lower than that of the underlying horizons and indicates a slight leaching of silica. The adsoiption complex is highly saturated and the dominant cations are calcium and magnesium. The high magnesium content of Balikh soils will be due to .weathering of marl in the upper course of the Balikh.

ECe and ESP values are low and the lime content is about 25 percent. Powdery lime accumulations are weakly developed or absent. The occurrence of cracks filled with clay and organic matter together with stress faces in subsoil and deeper subsoil are regarded as highly characteristic. The latter are due to the swelling and shrinking of montmorillonite as a result of marked changes in moisture content. The profiles are characterized by zones with prominent mottling. The occurrence of several levels with intensive mottling in profile 19 indicates in- termittent moistening. Cracks were observed up to a depth of 100 cm and are several centimeters wide. The organic matter in the cracks being protected against strong insolation is not destroyed and has a black colour.

145 a.2. Orthents . Entisols that 1. have textures of loamy very fine sand or finer; 2. have an organic matter content that decreases regularly with depth; 3. are not permanently saturated with water.

a.2.1. Torriorthents . Orthents that 1. have a mean annual soil temperature of more than 8°C (chapter I B,3); 2. are usually dry in most years.

a.2.1.1. Lithic Torriorthents.. Loamy soils overlying limestone within 30 cm of the surface are placed in this subgroup. No diagnostic horizons other than an ochric epipedon developed in the loam. These soils are found in places where a thin loamy cover is present on nd limestone outcrops in the if Balikh terrace.

a.3. Psamments. Entisols that 1. have below the (A ) horizon or 25 cm, textures of loamy fine sand or coarser in all parts to a depth of 1 m ; 2. are not permanently saturated with water.

a.3.1. To rripsamments . Psamments that 1. have a mean annual soil temperature of more than 8°C and a mean summer soil temperature of more than 15°C ; 2. are usually dry in most years in all parts of the soil between 18 cm and 50 cm; 3. have in the sand fraction, less than 95 percent quartz, zircon, tourmaline, rutile or other normally insoluable minerals that do not weather to liberate iron or alumina.

a.3.1.1. Typic Tor rips amments . These soils are found locally on the Euphrates lowest terrace and in some isolated patches of the Volcano area. 146 The Typic Torripsamments of the Euphrates area have a sandy texture up to lm. Those of the Volcano area are built up of coarse-textured lapilli without an admixture of loam or they are found in places where only the upper 25 cm or less are mixed. a.3.2. Ustipsamments . Psamments that 1. have a mean annual soil temperature of more than 8 C and a mean summer soil temperature at 50 cm of more than 15°C ; 2. are usually moist but are dry for 90 cumulative days or more in most years in some subhorizon between 18 and 50 cm but are not continuous- ly dry in all subhorizons between these depths for as long as 60 con- secutive days in more than 7 out of 10 years; 3. have in the sand fraction less than 95 percent quartz, zircon, tourmaline, rutile or other normally insoluable minerals that do not weather to liberate iron or aluminium. a.3.2.1. Typic Ustipsamments. Soils of the Euphrates flood plain which are sandy up to 1 m are placed in this subgroup. b. Aridisols of the Balikh Basin. b.l. Orthids. Aridisols that 1. have within 1 m of the surface one or more of the following horizons: calcic, gypsic, petrogypsic or cambic; 2. are usually dry between 18 and 50 cm depth or have a conductivity of the saturation extract that is 2 mmho per cm or greater at 25 C in some part above 125 cm if particle size class is sandy, 90 cm if loamy and 75 cm if clayey; 3. have a salic horizon with its upper boundary within 75 cm of the surface and are saturated with water within lm of the surface for one month or more.

147 b.1.1. Calciorthids. Orthids that 1. have either a calcic or gypsic horizon that has its upper boundary within 1 m of the surface; 2. are calcareous in all parts above the calcic horizon after the upper 18 cm are mixed unless textures are coarser than loamy very fine sand; 3. have no petrogypsic horizon within 60 cm of the surface; 4. have no salic horizon above the calcic or gypsic horizon. b.1.1.1. Typic Calciorthids. Calciorthids that a. have dominant chromas of 4 ore more; b. have a weighted average carbon content in the surface 38 cm of less than 0,58 percent if the weighted average sand/clay ratio for this depth is 1, 0 or less; or 0,16 percent if the ratio is 13 or more; or intermediate ratios have intermediate carbon contents; c. are usually dry between depths of 18 and 50 cm.

Six different families were recognized being loamy or clayey, loamy over fragmental, loamy over sandy gypsum, loamy over marl, marly and loamy lapilli, a. Typic Calciorthids; loamy or clayey (table 30.4 and 30.5). These soils are characterized by the occurrence of a calcic horizon locally underlain by a gypsic horizon. They developed in the loamy cover of the Pleis- tocene terraces and in the loams and clays of the Balikh alluvial. The loamy soils covering the Pleistocene terraces will be discussed first (table 30.4: profiles 5, 24, 31, 18, 26, 32, 38, and 42). The minéralogie assemblage is f airly uniform ; quartz, chalcedony, albite, orthoclase, illite and palygorskite are the dominant minerals. The content of montmorillonite was found to be slightly higher in the topsoil as compared with the underlying soil. A thin platy surface crust is underlain by a succession of the following structural horizons which gradually merge into each other: a horizon with crumbly structure; a horizon with subangular blocky structure ; a horizon with blocky structure.

148 The platy surface crust is usually cracked (distance from one crack to another 7. 5-12, 5 cm) and has a low clay content. A calcic horizon was found at different depths but generally between 40 cm and 70-100 cm. The secondary lime accumulated as white powdery fillings, concretions, pseudomycelia, pendants or crusts below pebbles and stones, and as thin sheets at the transition of loam into lapilli. The average percentage of calcium carbonate of the different soil horizons is as follows: (A) 20,0%, (B)22,0%, (1^)23,5%, (K„) 28, 5 and (Kg> 27,4 %. A gypsic horizon was found locally in the deeper subsoil (profile 42) or below a depth of 1 m (profiles 24, 8 and 38). Secondary gypsum accumulated as transparent crystals uniformly in the loamy material or as pendants under gravel and stones. A cambic horizon is situated above the calcic horizon and has fewer carbonates, the average difference between the two horizons being 6, 5 percent. The ochric epipedon contains on an average 8,5 percent carbonates less than the calcic horizon. A summary of properties is given in fig. 21.

soil horizon lime control- diagnostic designations ion! horizons ochric depth < 2% epipedon crunibl) (••y vol Lime cambic horizon

subangular 2-5 % blockv by volume

blocky 2M, 5 calcic bv volume horizon

3-5 % by volume

naie: The average permeability in k. 10-4 cm/secflstaelsen and Hansen, 1 !»62)

Fig. 21. Summary of properties of Typic Calcionhids

Although the aggregate stability is low, permeability appears to be related directly to soil structure. The very thin surface crust has a low permeability (D.S. Mclntyre, 1958).

149 The influence of the surface crust on soil permeability is illustrated by the lower permeability of the upper 10 cm which can only be due to the presence of this crust since the underlying layer has a good permeable crumbly structure. Below the crumbly topsoil permeability is decreasing owing to a subangular blocky structure merging into a blocky structure with low permeability.

Fig. 22. A Typic Calciorthid.

150 In the clay fraction, the silica/alumina ratios are relatively high and vary between 4 and 6,7. The Si O_/A1 O and Al O /FeoO_ ratios are given in fig. 23. Generally there is an increase of silica in the upper topsoil and deeper subsoil, while the lower topsoil and subsoil show a slight leaching of it. Profile 31 shows a relatively high increase of silica in the clay fraction of the deeper subsoil owing to a contribution of amorphous silica derived from volcanic glass. The SiO /Al O ratio of the total soil is only slightly higher than that of the clay fraction indicating a high content of clay minerals in the fine silt fraction which is an important quantity of soil.

AI203/Fe203 SiO2 / AI 2 o3 1 J 4 IS i S * T

/ fo / I v:{ 40 cms .

io \ .n o.

•o

fÛA toe

Soil profiles

Profile 5 Profile 24 Profile 37 Profile 31

Fig. 23. SiO /Al O and Al O /Fe O ratios of the clay fraction of Typic Calciorthids ( loamy )

The adsorption complex is highly saturated and the dominant cation is calcium.

The ECe and E.S.P. are generally low and the percentage of calcium carbonate varies between 15 and 30 percent. Salts accumulated in subsoil and deeper subsoil in some flat depressions and valleys (profiles 18, 24, 31, 38 and 42). These soils are only weakly saline and the effect of salts on plant growth will not be great. A moderate content of salt is met with occasionally in the lower part of soil (profiles 18 and 38).

151 Typic Calciorthids; loamy or clayey of the Balikh valley (table 30.5: profiles 37,8 and 34) differ from the Typic Calciorthids found on the Pleistocene terrace by the following properties: — texture is more heavy being silt loam over clay or clay loam; — the calcic horizon is less developed; — the crumbly structure of the topsoil is less developed; — the content of MgO of total soil and exchangeable magnesium are relatively high; — locally there is a very high percentage of calcium carbonate (profile 8). b. Typic Calciorthids; loamy over fragmental (Table 30.6: profiles 29,44-47).

The shallow loam soils overlying gravel were placed in this subgroup. The covering loam has a thickness of less than 30 cm. The soils have an ochric epipedon and a calcic horizon is more or less developed in the gravel. In some places a gypsic horizon developed e.g. profile 44. These soils are found on outcrops of the Pleistocene gravel where the covering loam is thin and the terrain is moderately to highly accidented. The soil material is highly calcareous and consequently calcium is the dominant cation of the adsorption complex. The chemical reaction is alkaline having a pH of 8,2. The development of a calcic and/or gypsic horizon in the gravel is dependent on the degree of accumulation and erosion of calcareous or gypsiferous loam. Erosion retards the development of these horizons while accumulation stimulates their development. Some leaching after wetting of the loamy surface layer during rainy periods will'lead to accumulation of lime and/or gypsum in the underlying gravel. No diagnostic horizons other than an ochric epipedon developed in the loamy top layer, this being rapidly removed owing to the high erosion forces acting in the accidented terrain in which these soils are found.

A classification of these soils as Lithic Calciorthids, having a lithic contact within 50 cm of the surface, would be more justified for practical reasons. However, the gravel being not coherent material cannot be classified as a lithic contact although it is not possible to penetrate with spade or auger but only with a pick-axe. Therefore, it is suggested to use the name Psephitic Cal- 152 ciorthids for such soils. c. Typic Calciorthids; loamy over sandy gypsum (table 30.7: profiles 6, 17, 39, 40 and 43).

The calcareous loamy top layers generally have the same soil properties as described for the Typic Calciorthids developed in the loamy cover over the Pleistocene terraces. However, the low situation in the terrain and being generally surrounded by gypsiferous outcrops together with the lower layers of highly gypsiferous material have a marked influence on soil properties. Therefore, in addition to the properties of the Typic Calciorthids which are more or less well developed, these soils are characterized by: — a generally weakly to moderately saline subsoil and deeper subsoil (profiles 17, 39 and 40); — development of gypsic horizons characterized by gypsum crystals in loam or cemented horizons in gypsum sand; — mottling in subsoil and or deeper subsoil; — highly gypsiferous soil layers which are stuctureless and have a low content of silica and alumina because of their low clay percentage. A very high percentage of calcium carbonate was met with in profile 6 which is situated in a valley surrounded by limestones. d. Typic Calciorthids; loamy over marl.

These soils are found in the northern part of the region where marl lies near the surface. A calcic horizon developed in the loam covering marl. e. Typic Calciorthids; marly.

These soils are found in the northern part of the region. They have the following characteristics: A white (10 YK. 8/2) calcareous clay with a granular structure, and lime mycelia at a depth between 20 cm and 100 cm, The organic matter content of the topsoil is low and a calcic horizon is more or less developed.

153 f. Typic C alciorthids ; loamy lapilli.

The loamy lapilli at the transition to the loam covering terrace often have below the ochric epipedon a cambic horizon underlain by a gypsic horizon and therefore were classified as Typic Calciorthids. b.1.2. Gypsiorthids . Orthids that 1. have a gypsic and/or petrogypsic horizon with or without gypsum polygones which has its upper boundary within 60 cm of the surface; 2. have a gypsum content of more than 25 percent in all parts of soil after the upper 30 cm or less are mixed. b.1.2.1. Typic Gypsiorthids (table 30.8: profiles 30, 10, 12 and 13). Gypsiorthids that a. have dominant chromas of 4 or more; b. have a weighted average carbon content in the surface 38 cm like the Typic Calciorthids (b. 1.1.1.); c. are usually dry between a depth of 18 cm and 50 cm.

Although gypsum sand has a deficiency in plant nutrients, is non-plastic and structureless, it inust be regarded as soil because it is able to support some kind of vegetation. Generally it has some admixture of more favourable soil material. The petrogypsic horizon cannot be regarded as a lithic or paralithic contact, the underlying material being not coherent or not partially consolidated. Whereas a petrocalcic horizon is the result of soil formation over a long continuous period, a petrogypsic horizon may be a rather recent formation. Therefore, the Gypsiorthids are not paleosols and cannot be classified as Paleorthids. The soil profile is characterized by three different layers (fig. 24): (a) aeolic calcareous silt or silt loam, underlain by (b) aeolic gypsum sand without small clay blocks or clay pebbles, underlain by (c) proluvial gypsum sand with small brown or grey clay blocks and pebbles, or small greenish-grey marl blocks. The aeolic silty top layer has a minéralogie assemblage indentical to that of the Terrace-Balikh province (see chapter III, A, 5). Locally a beginning of 154 Fig. 24. Typic Gypsiorthid. AeoLic silt loam is underlain by aeolic gypsum sand lying over clay mixed with gypsum. a calcic horizon was found in the thin loam cover. The gypsum deposits are composed for more than 30 percent of gypsum. The aeolic gypsum has an admixture of material which resembles that of the Terrace-Balikh province. The mineralogical composition of the clay fraction of the gypsum deposits differs from that of the covering loam in having a higher content of palygorskite, and montmorillonite Is often lacking. The clay blocks of the proluvial gypsum are found to have a minéralogie 155 composition rather similar to that of Miocene or Pliocene clay with palvgorskite and illite.or chlorite as dominant clay minerals. The C.E.C. and exchangeable magnesium and calcium are becoming higher downwards in the soil profile with increasing admixture of clay e. g. in profile 13. The sandy gypsiferous material has a low content of silica and alumina. The average content of silica of total gypsum soil (profile 30) is 14 percent. The soil solution is saturated with gypsum. The main soluble salts found in the 1:5 water extract are calcium sulphate, magnesium sulphate and some sodium chloride (profile 30). Low amounts of calcium and magnesium chloride occur in samples 10 II and 13 I. The gypsum content varies between 47, &",. and 74,9%. The aeolic silty top layer generally has an admixture of gypsum which can be as high as 37, 5%. The morphology of this silty layer is similar to that of the topsoil of Typic Calciorthids (loamy). The gypsum sand is structureless. A petrogypsic horizon or gypsumcrust is formed near the surface owing to dehydration of gypsum at temperatures higher than 38 C followed by solution and subsequent hardening after periods with rainfall. Gypsum being moderately soluble (2,6 grams per liter) is easily redistributed within the soil profile. The following gypsum accumulations due to solution and redistribution were observed: — fine crystalline gypsum cementing gypsum sand (profile 30); — moderate to coarse gypsum crystals where an underlying horizon has a low permeability e.g. above horizons with clay balls (profile 13); — filling of cracks in the gypsum crust (polygones); — recrystallisation of powdery gypsum crust and polygones into transparent crystalline gypsum plates; — pockets with coarse or fine crystalline gypsum in calcareous loam; — pendants at the bottomside of gravel and pebbles; — crystallised gypsum in root remnants. Gypsum polygones (fig. 25) preserved rather well owing to their vertical orientation. They are characterized by: — a laminary structure; — a tendency to a hexagonal structure; angles measured between polygonal plates vary between 110 and 130 ; with increasing age several plates dis- sappear and the pattern becomes more chaotic; 156 Fig. 25. Massive cr^'stalline gypsum polygones.

— the original powdery polygones can be converted after considerable time into massive crystalline gypsum plates; — sabakh phenomena which are often found where polygonal structures developed.

Fan-like oriented gypsum plates were observed in Miocene gypsum deposits but occur also at the surface of gypsiferous soils. Crystalline gypsum lying at the surface shows small solution pits, and cracking owing to alternating high and low temperatures. A powdery gypsumcrust is present in profile 13 between a depth of 15 cm and 45 cm while the profiles 10 and 12 have at a depth of 50-60 cm a layer of massive crystalline gypsum which in the latter profile is underlain by sandy gypsum. Lenticular hollows partly filled with vertical oriented gypsum needles developed near the soil surface in profile 10. 157 Fig. 26. Typic Cypsiorthid ( profile 10 ) with vertical oriented gypsum needles. b.1.3. Camborthids. Orthids that 1. have a cambic horizon; 2. have no calcic, gypsic or petrogypsic horizon that has its upper boundary within 1 m; 3. have no salic horizon with its upper boundary within 75 cm of the surface if saturated with water (i.e. within the capillary fringe) within 1 m of the surface for 1 month or more. b. 1.3.1. Typic Camborthids. (table 30. 9: profile 41). Camborthids that a. have a weighted average carbon content in the surface 38 cm of less than 0, 58 percent if the weighted average sand/clay ratio for this depth is 1, 0 or less; or 0,16 percent if the ratio is 18 or more;

153 or intermediate ratios have proportional carbon contents; b. are usually dry in all parts of soil between depths of 18 and 50 cm. These soils are found in the lapilli region and have a sandy loam texture. The upper 60 cm are intensively mixed with loamy material of the same mineralogical composition as the Terrace-Balikh province (chapter HI). The lapilli is composed mainly of olivine, volcanic glass, augite and nepheline.

Fig. 2r. Typic Camborthid developed in loamy lapilli.

159 Profile 41 has a low percentage of carbon in the upper 6 cm due to accumulation of material poor in organic matter. The underlying 11 cm have a higher content of organic matter. This profile has an admixture of loam up to 92 cm, is underlain by pure lapilli up to 150 cm and below this depth the lapilli is again mixed with loam. Apparently deposition of lapilli has found place simul- taneously with that of loam. In order to evaluate the influence of the basaltic lapilli on soil properties the chemical data were compared with those of the Typic Calciorthids developed in material of the Terrace-Balikh province. The chemical properties of the lapilli soils are markedly different. The deviating properties are given below (chemical analyses of profile 16, table 30.10, are also used): — although the chemical composition of the clay fraction of loamy lapilli soils is nearly identical, the content of silica is somewhat higher due to the high amount of amorphous silica derived from the lapilli; — the percentage of M O and Na O is higher in the lapilli (16 TV) owing to the g &. presence of olivine, nepheline and volcanic glass; —.thelapillihaveahighercontent of sand and grains>2 mm but a lower content of clay; — structure in lapilli soils is only weakly developed and shows, depending on the content of calcareous loam, only a tendency to blocky structure; — the pH of the topsoil is about 8. 7-8, 9 which is similar to that of the brown loam, but it is higher in lapilli rich material being 9, 0-9,4; — the percentage of carbon and nitrogen is lower; — the calcium carbonate content is lower; — the EC and E.S.P. are extremely high due to the sodium content derived from easy soluable volcanic glass and nepheline; — the composition of anions from the 1:5 water extract of soil is characterized by a higher content of chloride ions (profile 16 has a relatively high content of nitrate ions too) ; often salts accumulated at different depths and sabakh was observed at many places e.g. north-east of the Volcano.

The chemical composition of the parent material and weathering under arid conditions have largely prohibited soil formation. The high percentage of sodium and easy soluble salts were not favourable for plant growth, with the result that the organic matter content remained low and a crumbly structured topsoil did not form. In addition soil erosion by wind action is intensive due to the sandy texture and scarcity of vegetation. 160 b.1.4. Salorthids. Orthids that 1. have a salie horizon with its upper boundary within 75 cm of the surface if saturated with water (i.e. within the capillary fringe) within 1 m of the surface for 1 month or more ; 2. have no calcic or gypsic horizon above the salic horizon. b.1.4.1. Typic Salorthids (table 30.10: profiles 16). Salorthids that have a weighted average carbon content in the surface 38 cm like that of the Typic Calciorthids (b. 1.1.1.).

These soils contain lapilli and are found only locally in the Volcano region in low situated terrain. A salic horizon formed in the upper 48 cm of profile 16. The EC of 63 mmho corresponds to an approximate salt content of 2,6 percent. 6 Sodium chloride is the main component of the 1:5 soil/water extract, but sodium nitrate, sodium sulphate and gypsum occur in lower amounts and there is a subordinate content of calcium bicarbonate.

,3. A COMPARISON WITH OTHER SOIL CLASSIFICATION SYSTEMS

The various synonyms for these soils found in the literature e.g. Dewan (1959) and the "Soil map of the Near East (1963), Dudal (1968) are given below. Fluvents and Typic Ustipsamments are equivalent to Eutric Fluvisols or alluvial soils. Lithic Torriorthents and Typic Torripsamments can be classified as Rhegosols. Typic Calciorthids are approximately equivalent to Sierozems, Calcic Xerosols, Calcareous soils, Yellow soils (Strebel 1965), Cinnamonic soils (v. Liere), Arid brown soils (Jenny 1941) or Brown subdesertic soils (Kovda and Lobova 1961). Typic Gypsiorthids are referred to as Gypsic Xerosols, Sierozems, Desert soils and Gypsiferous soils. Dewan (1959) classified these soils as Rhegosols on gypsum and for being mostly saline as an intergrade between Rhegosols and Solonchaks. Typic Camborthids are referred to as Calcic Cambosols or Sierozems. Typic Salorthids are equivalent to Ochric Solonchaks, Halomorphic soils or White alkali soils.

161 Most of the Camborthids and Salorthids developed in lapilli-loam have an exchangeable sodium percentage of more than 15 percent and therefore can be classified as Alkali soils. This comparison does not mean that the various soil names used by different authors for soil types comparable with those in the Balikh Basin indicate soil types which are similar or identical, there maybe some deviation in properties between them.

4. THE SOIL MAP

A soil map with a scale 1:50.000 was compiled as the result of aerial photo interpretation, field observations, evaluation of soil analyses and subsequent classification of soils according to the "Soil Classification, A comprehensive system, 7th Approximation" (1960) with supplements (1964, 1967). This map is given in appendix HI and IV. Its legend corresponds to the division given in section B, 2 of this chapter. For mapping methods one is referred to chapter VII. There is a striking resemblance between the soil map and the morphological map ( fig. 9). The Azonal Entisols are found in the alluvial plains of Balikh and Euphrates while zonal Aridisols occur on the older plateau lands and the I terrace of the Balikh. The area with Gypsiorthids largely coincides with the Gypsum region, that of Calciorthids with the Terrace region and the lowest terrace of the Balikh, and Camborthids occur in the Volcano area. In order to show the spatial difference of soil genetic horizons along topographical forms, geo-pedological profiles were constructed. These are given in appendix II.

A calcic horizon developed if enough calcareous material was present for a continuous long period or when there was a regular supply of this material followed by leaching of carbonates. A repetition of calcic horizons was present in lower situated places on the Pleistocene terraces where several meters of loam accumulated (app. n, profile AA1). A gypsic horizon was found in calcareous loam in places where gypsum precipitated from drainage water coming from adjacent high terrains with gypsiferous outcrops. A gypsum crust (petrogypsic horizon) occurs where practically pure gypsum lies at the soil surface or at greater depth when buried un-

162 der loamy deposits (app. II).

C. Morphology and mic romo rphology of Aridisols of the Balikh Basin.

Thin sections (see Vul, A, 1) of Aridisols were studied with the aid of a microscope and structure photograms (2 x and 10 x enlargement). The quantimet method applied by Jongerius of the Dutch Soil Survey Insti- tute (Wageningen, The Netherlands; publication in preparation Geoderma) has been proved to be an adequate means for evaluation of porosity and degree and type of aggregation. The quantimet apparatus supplies several figures e.g. the surface porosity (A) in percentages and the perimeter of aggregates (P) expressed in projection units (P-units) ; a high P-value indicates a high degree of aggregation. The general methods for morphological description are given in the "Soil survey manual" (1951) and by Jongerius (1957). The micromorphological description was done after Brewer (1964) although in some cases completion was necessary. The indications used are defined below. — Skeleton grains of a soil material are individual grains which are relatively stable and not readily translocated, concentrated or reorganized by soil forming processes. — Plasma of a soil material is that part which is capable of being or has been moved, reorganized and/or concentrated by the processes of soil formation. — Plasma concentrations are concentrations of any of the fractions of the plasma in various parts of the soil material due to soil formation. — Plasma separations: features characterized by a significant change in the arrangement of the constituents rather than a change in concentration of some fraction of the plasma. — Soil structure : the physical constitution of a soil material as expressed by the size, shape and arrangement of the solid particles and voids. — Soil fabric: the physical constitution of a soil material as expressed by the spatial arrangement of the solid particles and associated voids. — A ped is an individual natural soil aggregate consisting of a cluster of primary particles, and separated from adjoining peds by surfaces of weakness which are recognizable as natural voids or by the occurrence of cutans. — Pedality: the physical constitution of a soil material as expressed by the 163 size, shape and arrangement of peds. — Pedality symbol: this has the following features, 1st. grade of structure or cohesion of peds (Soil survey manual) ; 0. structureless, 1. weak, 2. moderate, 3. strong; 2nd. accomodation (arrangement of peds) ; A . unaccomodated, A . partly accomodated, A . accomodated; 3rd. re-entrant angles (conformation of peds); R . weakly re-entrant (less than 1/3 of interfacial angles), R . moderately re-entrant (1/3-2/3 of interfaciel angles), R . strongly re-entrant (more than 2/3 of interfacial angles) ; 4th. surface of peds (shape of faces); S°. plane, S+. smooth, S++. curved. — Voids: these are interconnected in any material which consists of packing of individuals; soil materials can be regarded as having a single void of intricate shape which varies considerably in its dimensions ; -packing voids are due to random packing of individuals; -vughs are relatively large voids, other than packing voids, usually irregular; -vesicles have smooth, simple-curved walls, which are smooth and regular; -channels are very large voids with a generally cylindrical shape, smoothed walls and regular conformation; -planes are planar voids. — Soil matrix: this is the material within the simplest peds, it consists of the plasma, skeleton grains and voids that do not occur in pedological features other than plasma separations. — Plasmic fabric: the feature of the plasöia which deals with arrangement of the material within the simplest peds. 1. Asepic plasmic fabrics: these fabrics have dominantly anisotropic plasma with a flecked extinction pattern and no plasma separations. -Calciasepic fabric: the plasma of this fabric exhibits a flecked orientation and has an important proportion of carbonates e.g. 15-40 percent being of definite importance for the physical constitution of the soil material. -Argillasepic fabric : the plasma of this fabric consists dominantly of anisotropic clay minerals and exhibits a flecked orientation pattern with recognizable domains which have some degree of preferred orientation. 2. Sepic plasmic fabrics: these fabrics have recognizable anisotropic do-

164 mains with various patterns of preferred orientation; that is plasma separations with a striated extinction pattern (a linear or curved linear arrangement of the plasma aggregates) are present. -Skelsepic fabric : part of the plasma has a flecked orientation pattern, but plasma separations with striated orientation occur subcutanically to the surface of skeleton grains. 3. Crystic plasmic fabrics: the plasma is usually anisotropic and consists of recognizable crystals of the more soluble plasma fractions, being soluble in water e.g. gypsum and halite. -Allotriomorphic crystic fabric: the plasma is characterized by anhedral crystals. — Pedological features : recognizable units within a soil material which are distinguishable from the enclosing material. — Cutan: concentration of particular soil constituents or in situ modification of the plasma at natural surfaces in soil materials such as channels, peds and skeleton grains. — Grain cutans: cutans associated with the surfaces of skeleton grains or other discrete units, such as nodules, concretions etc. — Cutans are classified a.o. according to the mineralogical nature of the cutanic material: argillans (clay minerals); sesquans (sesquioxides or hydroxides); soluans (carbonates, sulfates and chlorides of calcium, magnesium and sodium) e.g. gypsans (gypsum) and calcitans (calcite). — Pedotubule: a pedological feature consisting of soil material and having a tubular external form with sharp boundaries. — Aggrotubules : pedotubules composed of skeleton grains and plasma which occur essentially as recognizable aggregates within which there is no directional arrangement with regard to the external form. — Isotubules : pedotubules composed of skeleton grains and plasma that are not organized into recognizable aggregates and within which the basic fabric shows no directional arrangement with regard to the external form; the basic fabric is essentially porphyroskelic. — Striotubules differ from isotubules in having a basic fabric with a directional arrangement related to the external form. — Mull or clay-humus accumulations: biogenical mixed complexes of clay and very fine grained strongly humified organic matter. — Glaebules are three dimensional units within the soil matrix and are usually approximate prolate to equant in shape. Their morphology is incom- 165 patible with their present occurence. — Nodules are glaebules with an undifferentiated fabric, that is, there is no specific orientation pattern with regard to the shape of the glaebule. — Concretions: glaebules with a generally concentric fabric about a center which may be a point, a line or a plane. — Intercalary crystals: crystallaria that consist of single large crystals or groups of a few large crystals set in the soil material and apparently not associated with voids of equivalent size or shape.

1. TYPIC CALCIORTHIDS; LOAM COVERING PLEISTOCENE GRAVEL

For field description and analyses one is referred to table 30.4, profile 38. a. Morphology. (A ) 0-5 cm Platy structure (fig. 28), 2A++R+S°+, very thick plates of 12 mm subdivided in thin plates of 2 mm, surface porosity 18%, perimeter of aggregates 2,3 P-units. (B) 5-19 cm Crumbly structure (fig. 29) of which are: (a) 47 percent unaccomodated, 2A R S , surface porosity 28%, perimeter of aggregates 7,6 P-units; (b) 2 percent partly accomodated, 2A R S , surface poros- sity 25%, perimeter of aggregates 5 P-units; (c) 9 percent concentric, 2A R S , surface porostty 9, 5%, perimeter of aggregates 2,9 P-units; (d) 42 percent reorganized a-b-c, 2A R S , surface porosity 18,3% perimeter of aggregates 5,6 P-units. (K.) 19-50 cm Subangular blocky structure, 3A R S , surface porosity 19,3%, perimeter of aggregates 2, 8 P-units locally rich in aggrotubules with unaccomodated aggregates, surface porosity 20, 0-25,6%, perimeter of aggregates 7,0-8,2 P-units. (K„) 50-105cm Blocky structure, 3A R S , relatively porous with a sur-, face porosity of 18,4% and a perimeter of aggregates of 4, 5 P-units to compact with respectively 11, 6% and 2, 7 P-units; locally aggrotubules with unaccomodated aggregates.

The amount of coarse aggregates in the aggrotubules is increasing down- 166 wards in the soil profile. A surface porosity of 46,6% and a perimeter of aggregates of 5 P-units was met where the unaccomodated aggregates of aggrotubules were connected by thin bridges of soil plasma. b. Micromorphology.

Skeleton grains are of silt and sand size; gravel occurs also. They have an angular habit and are found at irregular distances from each other. The grains are embedded in calcitic plasma and the associated micróvughs are often filled with calcite or gypsum. The plasma grains are of 3-10 n size or smaller, are closely packed together and the plasma is composed of clayandhighlyirregularcalcitemicrolites. The characteristics of the different soil horizons are given below.

(A-1) 0-5 cm Calciasepic fabric with vughs and planes; 30 percent of the soil plasma is built up of calcite microlites; vesicles separately or interconnected to planar voids; very few calcareous glaebules, calcitans; few aggrotubules, some organic isotubules and mull accumulations; small sesquioxidic nodules (approx. 53percm^. (B) 5-19 cm Calciasepic fabric with vughs and channels; 36 percent of the soil plasma is built up of calcite microlites; few calcareous glaebules, calcitans; many aggrotubules, some organic isotubules and mull accumulations; small sesquioxidic nodules (approx. 49 per cm ).

(K1) 19-50 cm Calciasepic fabric with vughs and channels; 40 percent of the soil plasma is built up of calcite microlites; many calcareous glaebules, calcitans; many aggrotubules and some organic isotubules, mull accumulations; small sesquioxidic nodules (approx. 32 per cm), (K„) 50-105cm Calciasepic fabric with vughs and channels; 60-65 percent of the soil plasma is built up of calcite microlites; many calcareous glaebules, calcitans; aggrotubules and some organic isotubules, few mull accumulations; small sesquioxidic nodules (approx. 23 per cm ).

167 The calciasepic fabric (fig. 30) is characterized by plasma concentrations that are: — of calcitic nature surrounding skeletal grains; — of clayey nature surrounding skeletal grains; — of clayey nature surrounding places with a higher content of calcitic plasma. c. Organization within the pedological features.

The aggrotubules are built up of randomly packed aggregates. These often have an angular habit but spheroidal and ellipsoidal aggregates were found. The angular forms are the result of burrowing activity while the other are faunal excreta. The latter are often composed of clay and humus and were found throughout the soil matrix. Locally isotubules with randomly packed skeleton grains and clay-humus plasma were found (fig. 31). Channel cutans of this material occur also. The calcareous glaebules have a concentric fabric on the outer sides (fig. 32) but the internal fabric is essentially calciasepic (fig. 33). The sesquioxidic nodules have a size of about 50-250 n. are irregular and have an undifferentiated fabric.

2. TYPIC CALCIORTHIDS; HOLOCENE LOAM OF THE BALIKH

For field description and analyses one is referred to table 30.5, profile 37. a. Morphology. (A ) 0-15 cm Coarse, porous crumbly structure, 2A R S ; locally subangular blocky structure, 3A R S , surface porosity 9% and perimeter of aggregates 2, 3 P-units; few aggrotubules with . unaccomodated aggregates ; few segmented striotubules (fig. 34), surface porosity 22,2% and perimeter of segments 2,4 P-units; locally unaccomodated aggregates connected by a bridge of soil plasma with a surface porosity of 34% and a perimeter of aggregates of 4,0 P-units. (B) 15-32 cm Subangularr blocky structure, 33AA +RR +S O++ , surface porosity 11, 2%, perimeter of aggregates 2,6 P-units; few aggrotu-

168 bules with unaccomodated aggregates.

(K21) 32-63 cm Blocky structure, 3A R S°, surface porosity 20%, perimeter of aggregates 2,8 P-units; few aggrotubules with fine and often coarse aggregates. ++ + 0+ (K22) 63-100cm Blocky structure (fig. 35) 3A R S , surface porosity 24%, perimeter of aggregates 3, 5 P-units; very few aggrotubules with coarse aggregates.

The lime concretions have a very low surface porosity of 4,7%. b. Micromorphology.

Skeleton grains are of silt and sand size , have an angular habit, are found at irregular distances from each other and are embedded in plasma or have associated microvughs. The plasma grains are of 3-12 p, size or smaller, have a highly irregular habit and are closely packed together. The plasma is composed of clay and calcite. The characteristics of the different soil horizons are given below: (A..) 0-15 cm Calciasepic fabric with vughs and channels; 33 percent of the soil plasma is built up of calcite microlites; calcareous glaebules, calcitans; few aggrotubules and striotubules, few to medium amount of mull accumulations ; small sesquioxidic nodules (approx. 53 per cm ). (B) 15-32 cm Calciasepic fabric with vughs and channels; 45 percent of the soil plasma is built up of calcite microlites; calcareous glaebules, calcitans; many mull accumulations; small sesquioxidic nodules (approx. 32 per cm ).

(KO1) 32-63 cm Calciasepic fabric with vughs and channels, 43 percent of Ax the soil plasma is built up of calcite microlites; many calcareous glaebules, calcitans; few aggrotubules filled up with fine granular or coarse material, small sesquioxidic nodules (approx. 31 per cm ).

(K22) 63-100cm Calciasepic fabric with vughs and channels; 43 percent of the soil plasma is built up of calcite microlites, many calcareous glaebules, calcitans; few mull accumulations, small sesquioxidic nodules (approx. 25 per cm ). 169 3. TTPIC GYPSIORTHIDS

For field description and analyses one is referred to table 30.8, profile 13. Intercalary gypsum crystals are 60-140 p,or larger. The plasma is composed of argillaceous material and fine-grained gypsum and calcite. Micromorphology: (A) 0-15 cm Calciasepic to crystic fabric (fig. 36) with vughs and channels; granular aggregates (size 60-250 n) with calcareous- argillaceous plasma are found throughout the soil matrix; few calcareous glaebules, often with cracks impregnated with gypsum; few aggro tubules, few mull accumulations; few sesquans; calcitans and gypsans. IIC^ 15-45 cm Crystic to calciasepic fabric (fig. 37); few granular aggregates with a calcareous-argillaceous fabric; clay blocks, often with cracks impregnated with gypsum; intercalary gypsum crystals; calcitans and gypsans. IIC- 45-90 cm Crystic to argillasepic fabric (fig. 38) with intercalary gypsum crystals and many clay blocks; grain argillans; calcitans and gypsans. Micromorphology of gypsum crusts; A gypsum crust has an allotriomorphic (Tyrrel 1956) crystic fabric showing anhedral crystals of gypsum (fig. 39). Gypsum polygones are characterized by a parallel arranged crystic fabric, (fig. 40). Small gypsum crystals are arranged parallel to the vertical sides of the polygones while anhydritic skeletal grains have a random arrangement.

4. TYPIC CAMBORTHIDS DEVELOPED IN LAPILLI MIXED WITH CALCAREOUS LOAM

For field description and analyses one is referred to table 30.9, profile 41. The skeletal material is built up of lapilli, olivine (Volcano province), feldspar and quartz (Terrace-Balikh province). The soil plasma is builtupof calcareous-argillaceous material locally mixed with soluble silica derived from volcanic glass. The amorphous groundmass of weathered volcanic glass at the surface of the lapilli grains has been coloured at many places due to accumulation of amorphous iron oxihydrate (fig. 41 and fig. 42).

170 Iron-rich silicon dioxide accumulated in the calcareous-argillaceous soil plasma (fig. 42) and locally is partly coating skeleton grains. A skelsepic fabric found in these soils is weakly striated and may be regarded to be the result of sedimentary processes. Rolling of lapilli and loamy material due to wind action will result in orientation of the latter parallel to the surface of the lapilli grains.

Micromorphology: (B) 6-54 cm Skelsepic to calciasepic fabric with grain silans and calcitans, few sesquans, small calcareous glaebules ; calcareous argillaceous plasma arranged parallel to the surface of skeleton grains and lapilli (rounded lapilli grains have more surrounding parallel arranged material than angular grains do have); very fine granular aggregates are found between zones with parallel arrangement. C 54-92 cm Skelsepic to calciasepic fabric with calcitans and few grain silans and sesquans; a primary stratification of lapilli and granular loamy aggregates is present and there is a parallel arrangement of calcareous-argillaceous plasma to the surface of lapilli grains.

1 mm Fig, 28. Platy structure of a Typic Calciorthid; loam covering Pleistocene gravel ( thin section in plain light ).

171 ••r?r^

• ^w* • ••••

1 cm

Fig. 29. Crumbly structure of a Typic Calciorthid; loam covering Pleistocene gravel ( structure photogram). a. Un accomodated aggregates, c. Concentric fabric. b. Partly accomodated aggregates. d. Reorganized a - b - c. 172 100

Fig. 30, Calciasepic fabric ( thin section under crossed niçois }. a. Calcareous plasma with clayey admixture, b. Argillaceous plasma with calcareous admixture. c. Calcitans. d. Voids. e. Skeleton grains. f. Mull accumulations.

173 250^

Fig. 31. Muil accumulation in ïsotubule (thin section under crossed niçois).

Fig. 32, Calcareous tjîaebule ( thin section under crossed niçois

174 250,

Fig. 33. Calciasepic fabric of calcareous giaebuies with caicitans. (thin section under crossed niçois).

1 cm 1 cm

Fig. 34. Striotubule and siibangular blocky Fig. 35. BlocKy structure { structure photogram). structure ( structure photo<|ram ].

175 500,

Fig. 36. Calciasepic to crystîc fabric ( thin sect ion under polarizer rotated through 30 ) with : a. calcareous- argillaceous plasma; b. gypseous - calcareous plasma with pores; c. calcitans.

176 '1 II 1 il II II

800

Fig. 3/. Crystic to calciasepic fabric ( thin section under crossed niçois ) with : a. calcareous - argillaceous plasma; b. gypseous - calcareous plasma with pores; c. calcitans; d. voids; e. gypsans.

177 800 y,

Fig. 38. Crystic to argillasepic fabric { thin section in plain light ) with grain argillans.

800,

Fig. 39. Allo tri omorphic crystic fabric of a gypsum crust ( thin section under crossed niçois ).

178 800 p,

Fig. 40. Parallel arranged crystic fabric of gypsum polygones ( thin section under crossed niçois ).

Fig. 41. Accumulated amorphous iron oxihydcate at the surface of a lapilli grain ( thin section in plain light ).

179 200 i

Fig. 42. Asepic fabric of lapilli mixed with calcareous loam ( thin section in plain light ). a. Calcareous - argillaceous plasma with voids. b. Opaque volcanic glass with augite and olivine microlites. c. Light greenish grey volcanic glass. d. Brown volcanic glass rich in iron oxihydrate. e. Skeleton grains. f. Calcareous - argillaceous plasma impregnated by brown iron oxihydrate. and silica. g. Vesicles.

180 CHAPTER IX

SOIL GENESIS IN THE BALIKH BASIN

The different soil forming processes and the resultant profile development as related to time are dealt with in this chapter. The rain water penetrating into the soil is either held by the soil particles or moves upward again and evaporates at the soil surface or is transpirated by the plants. The products of weathering are not removed from the soil through leaching owing to the scanty rainfall. The low amount of silicium and aluminum released from the primary minerals may furnish a skeleton for clay colloids. Iron compounds may be subject to a mild reduction, however, oxidation is dominant and determines the soil colour. Alkali and alkaline earth are present in the soil solution in minor amounts and largely determine the soil properties. While sodium and potassium disperse clay colloids, calcium and magnesium have a high flocculating power and ensure soil stability.

A. Soil forming processes.

1. SOIL PHYSICAL PROCESSES.

Alternate wetting and pronounced drying combined with the splitting action of plant roots resulted in a fragmentation of loamy or clayey soil material and the development of a blocky structure (Jongerius 1957). A thin platy surface crust of one to five centimetres developed by the ac- 181 tion of raindrop impact (Mclntyre 1958) which causes the soil aggregates to break down. If dispersion takes place the finer material is washed into surface pores and reduces their volume. Continued impact causes compression of the surface producing a skin seal of about 0,1 mm thick. Where the soil air has been captured immediately under this seal, triaxial vesicles form and slight pressure causes rupture into plate-like fragments parallel to the surface (Brewer 1964). Excessive drying during the dry summer induces cracking of the surface crust. In addition the repeated evaporation and wetting are factors which promote the formation of a platy structure (Jongerius 1957). Clayey soils in the alluvial plains are subject to intensive crack formation due to alternate wetting and drying. Locally cracks up to 1 m depth are formed During the summer some material of the (A) horizon falls into these cracks and in the rainy season the soil material expands. Swelling pressure develops in all directions and slickensides are formed in the horizon underlying the main expanding layer (Dan, Yaalon 1966).

2. SOIL BIOLOGICAL PROCESSES.

The upper five or ten centimeters of the ochric epipedon generally have a carbon content of 0, 90 percent which rapidly drops below this depth to about 0, 30 percent. The carbon/nitrogen ratio of this surface layer is about 8. The low carbon content and carbon/nitrogen ratio are due to: — the sparsity of the plant residue ; — the predominance of oxidizing decomposition due to high summer temperatures; — the action of soil microflora (bacteria) and fauna (mites and insects). During spring there is an intensive flush of vegetation and microbiological activity depending on the conditions of temperature and moisture. During this short period not only a new formation of humic substances but also their subsequent decomposition will occur (Kononova 1961). The biological processes in Typic Calciorthids on the terraces are discussed below. Mites, insects and their larvae most probably caused the relatively intensive processes of redistribution of organic matter into deeper soil layers (mull-accumulations) and the formation of a great number of aggrotubules (also mammals could have played their part with the latter formation). 182 Under the platy surface layer a crumbly structure has been formed of which 47 percent is unaccomodated due to the action of mainly burrowing soil fauna, 2 percent partly accomodated and 9 percent concentric from mainly consuming soil fauna, the rest being reorganized. Two different types of unaccomodated crumbly structure were observed, these have : — aggregates of various size and usually angular due to burrowing activities ; — aggregates of nearly equal size and usually rounded (fecal pellets) due to both burrowing and consuming activities.

The subangular blocky structure forms a transition between the biological crumbly structure and the physical blocky structure, the blocky peds being rounded on some edges by the activity of soil fauna and roots (Jongerius 1957). The relation between subangular blocky structure and activity of roots and soil fauna may be deduced from the following observations: — a subangular blocky structure was observed between 25 cm and 40 cm; — the roots of gramineae generally are restricted to the upper 10 cm. Below this depth roots of shrubs have penetrated up to 40-60 cm; — the activity of burrowing soil fauna is not restricted to the topsoil for aggrotubules were found also in the deeper subsoil.

Biological activity has not resulted in the formation of a pronounced crumbly top layer in Typic Calciorthids of the Balikh. However, the accumulation of humus in deeper soil layers is greater than in soils on the terraces and the occurrence of earthworm casts together with a relatively great quantity of skeletal chitine indicate a rather high biological activity. , Aggrotubules are more rapidly reorganized in these soils due to the greater wetness thus leaving not much witness of the action of soil fauna. The great influence of the rooting system on structure formation may be deduced from the combination of a weak structure with a poor rooting system in chemically and/or physically unfavourable soil layers. This was observed in a loamy lapilli layer at a depth of 72 cm and in gypsiferous soil (53 percent of gypsum) at a depth of 45 cm below the soil surface.

183 3. SOIL CHEMICAL PROCESSES. a. Relatively soluble constituents. a.l. Calcium carbonate. Carbonates tend to accumulate between 40 cm and 70 cm below the soil surface that is the average depth of penetrating moisture. The process causing their mobility is the so-called carbonation which is active amongst others in the presence of calcium and magnesium containing minerals. Rain water passing through the atmosphere takes up a small amount of carbon dioxide, and coming into soil more is supplied by oxidizing organic matter. The calcium carbonate reacts with the carbon dioxide containing soil water and calcium bicarbonate forms which moves with the percolating water downwards in the soil profile. Practically pure precipitates of calcium carbonate form when the carbon dioxide pressure in the soil solution decreases, this being the case after percolation or capillary rise followed by evaporation of soil water. Accumulations of this material were found in the following forms: — calcareous glaebules; — calcitans e.g. grain and channel cutans; — impure calcareous accumulations in the soil matrix.

Deposition from carbonate-charged water results in an active aggradation of irregular-shaped calcite microlites at many places in the soil matrix with as a consequence a passive concentration of argillaceous material (calciasepic fabric, fig. 30). With time the number of calcite microlites is increasing at such places and more clay is pressed sidewards. The final stage is a glaebule with a dense calcareous internal fabric enclosing some skeleton grains and surrounded by argillaceous and calcareous zones which are arranged concen- trically. Below a cambic horizon from which carbonates are leached, a calcic horizon developed during the arid Holocene. A petrocalcic horizon or carbonate crust formed under more humid conditions during the Pleistocene. Rests of this crust are found locally in terrace material where it cements gravel.

184 a.2. Gypsum . Gypsum having a moderate solubility of 2,6 grams per liter is easily redistributed in the soil profile (fig. 26). A gypsic horizon was found in many soils below the calcic horizon and at its top some mottling occurs. Gypsiorthids having a gypsum content of mo re than 25 percent are characterized generally by the occurence of a gypsumcrust (petrogypsic horizon) with polygones. Gypsum dehydrates into hemihydrate at a temperature of 38 C. This takes place during summer when values of 42°C are reached in soil at a depth of 10 cm below the soil surface (chapter I, B, 3). Moistening during winter results in hydration and solution of hemihydrate and subsequently the formation of a hardened gypsumcrust with an allotriomorphic crystic fabric (fig. 39). Its morphology is dependent on the degree of moistening. Thoroughly wetting results in the formation of a dense fine crystalline surface crust with vesicles and vughs as a result of the action of escaping air. However, less pronounced wetting leads to the development of a more porous crust accompanied by cracks which have an irregular and locally hexagonal arrangement. Excessive drying during summer causes renewed dehydration and formation of cracks often with a hexagonal pattern (such patterns were observed too in weathered gypsum rock). During wet periods these cracks were filled up with gypsum microlites which are arranged parallel to the sides (fig. 40). Polygones thus formed are more resistant against solution processes than the gypsumcrust owing to their vertical orientation. Therefore, they are found often in places where the crust had been dissolved long ago. There is an active migration of chemical constituents towards these polygones (e.g. Sabakh phenomena) and with increasing age they generally become massive crystalline.

a.3. Soluble salts (more soluble in cold water than gypsum). Soluble salts have been accumulated by percolating water in the deeper subsoil or after subsequent evaporation in the topsoil. Salt efflorescences are found at the. soil surface in: — depressions of the Terrace region which are occasionally flooded by salt- containing seepage water of higher grounds ; — lapilli soils having a high sodium content; — irrigated soils after inadequate application of water. 185 Sabakh phenomena, which are accumulations of calcium and magnesium chlorides, were abundant in lapilli and gypsum soils, in the latter associated with the occurrence of polygones . Thesesalts being hygroscopic appear as dark patches at the soil surface in the morning if night dew occurred. b. Relatively insoluble constituents.

Their mobility is low and therefore no diagnostic horizons characterized by them were formed. b.l. Silica. About 30 percent of the quartz grains studied had a strongly weathered appearance due to frosting as a result of corrosion and mechanical impact during aeolian transport. This is generally known as a desert patina which can be regarded tobeindicativeof the instability of this mineralunder arid conditions. Keller (1958) states the following about the solubility of silicon dioxide of aluminum silicate minerals: silicon dioxide is potentially soluble where the pH at the hydrolizing interface of aluminium silicate minerals is 7-9,5 but its solubility is low and large amounts of soil water must be available to remove such silica in solution. In arid regions the rate of hydrolysis is retarded owing to the scanty rainfall,but the high temperatures and the high pH, being about 8,6 in Calciorthids, are favourable for dissolving of silica. However, the high concentration of calcium and magnesium ions in the soil solution results in flocculation of SiC* and A1_O and consequently lower their mobility. In addition, the uptake of silica by plants in the topsoil and the formation of phytoliths (chapter V, A, 4) retards leaching of silica.

In spite of its low potential mobility under these conditions, the SiO2/Al2O„ ratio slightly increases downwards in the soil profile of Calciorthids indicating some leaching of silica (fig. 23). Silicon dioxide was found to be more mobile in lapilli soils (Camborthids) with a high concentration of sodium in the soil solution, a pH value of 9, 0 and an abundance of easily soluble volcanic glass. Iron-rich amorphous silicon dioxide accumulated in the soil matrix which surrounds the lapilli grains rich in volcanic glass (fig. 42).

186 b.2. Sesquioxides . Iron oxides and hydroxides are formed in situ from ferruginous minerals by oxidation, hydration and hydrolysis. Oxidation is active during the greater part of the year but hydration and hydrolysis only in the short rainy period. For the mobilisation of sesquioxides in soils of arid regions, a protective colloid is indispensable on account of the flocculating action of lime. Because of the small amount of humus and its saturated state preventing it to function as a protective colloid, silicic acid will be the only agent for this (Reifenberg 1947). There will be an optimum peptisation if the soil reaction is characterized by a high pH value, and a high content of alkali is promoting it. Therefore, the chemical conditions in the alkaline Camborthids of the Volcano region may be regarded to be favourable for this process. Amorphous iron oxihydrate was found to be translocated over short distances in these soils, (fig. 41 and 42). However , the precipitation is too low to cause significant leaching of these substances. While ferric oxides and hydroxides are only slowly soluble at a pH >3, the ferro compounds can be dissolved at that pH range. Under the temporarily wet conditions in soil they can be transported as ferro hydrocarbonates (Scheffer und Schachtschabel 1960). It may be concluded that three processes are active in weathering or mobilisation of iron compounds in arid soils, these are the protective colloidal action of silicic acid, carbonation of ferro oxides and hydroxides with their subsequent transport as ferro hydrocarbonates, and oxidation. The hematite (aFe.O ) and wustite (FeO) found in the loamy material of Li O Terrace-Balikh and Volcano regions (chapter m, A, 5, a) probably were partly formed in soil after deposition. Wustite will be associated with temporarily anaerobic conditions for which indications were found in the following forms: — wet conditions in zones bordering the flood plain of the Balikh during a great part of the year; — a faint mottling at a depth of about 1 m often followed by a gypsic horizon in Calciorthids of the Terrace region; — sesquioxidic nodules in Calciorthids of the Terrace-Balikh region.

Drosdoff and Nikiforoff (1940; quoted by Brewer, 1964) suggested that sesquioxidic accretions are formed by an initial drying that causes concentration of solutions in the small voids, thus initiating the formation of nuclei of deposition. This process may have played an important part in soils of the Balikh

187 Basin. Hematite may be formed from ferro oxides and hydroxides due to dehydration and/or oxidation processes during the dry season. Conditions for translocation of aluminum oxides are less favourable, the protective colloidal action of silicic acid being the only agent able to remove it at the pH range of 8-9. At this pH one could expect a direct bauxitization; however, the conditions for leaching of silica being unfavourable prevent a concentration of alumina. c. Clay minerals.

In dry climates the rate of hydrolysis is low due to the scanty rainfall and therefore more time is necessary for a given reaction. There is an increase in concentration of silicium, aluminum and other metal ions owing to evaporation of water from the weathering system. As the concentration of metal ions builds up they may recombine at the energy level of the weathering environment to form clay minerals (Keller, 1958). The weathered residue of micas, pyroxenes and amphiboles may be converted in certain types of clay minerals (Van Schuylenborgh and Sänger 1950). Keller and Frederickson (1952; quoted by Parfenova and Yarilova 1962) pointed out the importance of the action of plant roots in liberating elements of the crystal lattices of the primary minerals. The elements thus liberated together with components of the soil solution, which are derived from hydration, hydrolysis and carbonation, are partly absorbed by the plants and subsequently returned to the soil with the plant residue, but in a condition of higher chemical activity e.g. calcium oxalate, phytoliths (chapter V, A, 4) and organometallic compounds. The fine rooting system of grasses is regarded to be favourable for this process in having a large chemical active surface. The mineralization of the plant residue leads to the synthesis of various products including clay minerals. The silica/alumina ratio of the clay fraction in soils of the Balikh Basin generally is higher than 5 which corresponds to the high pH (>8). Some clay has been formed in the (A) and (B) horizons. Palygorskite was found to be cemented into clusters in these horizons (chapter VIII, A, 2), this being due to weathering of this mineral which has led to the formation of montmorillonite (chapter III, B, 2) in Calciorthids of the Terrace region. Illite probably formed in the (A) horizons of Fluvents (table 30.3, profile 15) 188 and the top layers of Calciorthids (table 30.5, profile 37) from the Balikh region. High pH values and high concentrations of magnesium and calcium are indispensable for formation of montmorillonite while high concentrations of potassium ions in the presence of calcium ions lead to the formation of illite. The high calcium content of the soils has prevented the movement of clay into underlying soil horizons. The brown loamy material of the Aridisols originated from the Tertiairy residue, both having palygorskite and illite as dominant minerals in the clay fraction. Comparison of the state of weathering of the soil material with that of the residue showed that weathering after deposition was low since the deviations between these materials are relatively small.

B. Soil formation as related to time.

For palaeo-climate^ne is referred to chapter I, A, 10 (table 10), for the ages of the different deposits to chapter II, A, 2 and B, and for the history of land use to chapter VI, 1. The youngest soils found in the area are the Ustifluvents and Ustipsam- ments of the flood plains of Euphrates and Balikh which are Post-Medieval, that is with a maximum age of 450 years. The Torrifluvents and Torripsam- ments of the lowest terrace of the Euphrates are prehistoric up to Byzantine that is older than 1300 years. st The lowest terrace of the Balikh is older than the I terrace of the Euphra- tes, witness the tals build up between 5600 B.C. and 2500 B.C. The Calcior- thids found on it correspond to this period while those developed in the loam covering pleistocene gravel are older, that is Late WUrm-Preboreal-Boreal, in having a/more pronounced profile development. TheCàmborthids developed in the lapilli correspond in age to the beginning of the Holocene that is about 8500 B.C. Deposition of proluvial gypsum took place at the start of the Pleistocene. Since that time this deposit was attacked by weathering agents, resulting in dissolving and redistribution of gypsum,witness karstic features and massive crystalline gypsum polygones which may be regarded as palaeo-formations. i Gypsiorthids with powdery crusts and porous crystalline lenses were regarded to be rather recent formations under arid conditions. The carbonate crusts found in the Lower and Middle Pleistocene gravel bear witness of more intensive soil formation during Pleistocene times. 189 Soils will "grow upwards" if wind action and run-off result in accumulation of material in the topsoil. That this happened with soils of the Balikh Basin is shown by the repetition of calcic horizons in Calciorthids of the Terrace region in depressions and valleys (appendix II). The accumulation of material does not continue over long periods, so the soil will be left alone for some time enabling it to reach a certain stage of development which is normally characterized by the occurrence of a calcic and/or gypsic horizon. There is some leaching of carbonates and weathering of minerals in the (A) and (B) horizons of Aridisols which led to new formation of montmorillonite and or illite. Summarizing, it can be stated that in places where accumulation of material exeeded erosion of it, the arid conditions have led to the development of a soil column with a thickness of several meters characterized by a repetition of calcic and/or gypsic horizons, and an increased percentage of montmorillonite and/or illite.

190 SUMMARY

This thesis contains a study of soil forming factors and genesis of the soils occurring in the Balikh Basin (Jazirah, Syria). The following sediments served as parent material for soil development: — brown loams covering Pleistocene gravel or filling up valleys in the different regions; — brown loams of the Balikh alluvial; — sandy gypsum, the topsoils being mixed with loam; — lapilli, the topsoils and subsoils being mixed with loam; — loamy and sandy Euphrates alluvial.

Analyses were performed to obtain the following data in order to evaluate soil genesis and to classify the soils: — minéralogie composition of the different soil fractions<2 p., 5-10 p., 20-30 p., 2-50 p., and 50-500 p.; — soil analytical data of the fine earth <2 mm; — chemical composition of the fractions < 2 P>, 5-10 p., 20-30 P- , and <2 mm.

The soil profile of the brown loams is rather homogeneous as regards texture and mineralogical composition; they originated from the Tertiairy residue. The acting climate is of the arid type with dry hot summers and cool relatively humid winters, the average yearly precipitation being 183 mm. Rainfall has an aperiodic nature which malies dry farming a rather risky enterprise. The Pleistocene was characterized by interpluvial and pluvial periods witness e.g. the terraces formed, the valley systems of the plateau lands and the karstic features in proluvial gypsum deposits. The valleys of the plateaus serve

191 •at the present time as a drainage system for mud-loaded water after occasional torrential rains. Dust storms occur frequently as a result of aridity and high wind velocities. There is accumulation of soil material in depressions and valleys due to aeolic action and run-off processes. Groundwater is generally saline and lies at a depth of about 20 m below the plateaus. Fresh water occurs in the flood plain of the Euphrates. Growth of plants is restricted to spring time. They rapidly complete their life cycle during this time and then lie dormant in the form of seeds. Generally there is a poor vegetation of mainly gramineae. Typical saline plants and weeds occur in the Euphrates valley; shrubs are abundant in the Balikh valley; valleys on the plateaus have their own characteristic type of vegetation in having more bulbs and grass than their surroundings. Soil fauna e.g. mites and insects redistribute organic matter into deeper soil layers and markedly influence soil structure especially in the dry loams of the terraces. The soils were classified according to the "Soil classification, a comprehensive system, 7th approximation" (1960) with supplements (1964, 1967). Fluvents, Orthents, Psamments, Calciorthids, Gypsiorthids (new great group), Camborthids and Salorthids were encountered , and a soil map 1:50.000 was constructed. The different soil forming processes are dealt with in the final chapter about soil genesis e.g. the formation of calcareous glaebules, gypsum crust and polygones, the accumulation of soluble salts, the mobility of silica and uptake of it by plants, mobility of sesquioxides and formation of nodules, the formation of clay minerals in the (A) and (B) horizons , and soil formation as related to time.

192 LITERATURE

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193 ELGABALY, M. M. and KHADR, M. 1962. Clay mineral studies of some Egyptian desert and Nile alluvial soils- J. of Soil Sei. Vol. 13. No 2. ERHART, H. )$$6. ^a genèse dee SOIB en tant que phénomène géologique« Esquisse d'une théorie géologique et géochimique. Bioataeie et RhexistaBie. Masson et Cie, Editeurs-Paris. ETRE,*S. R. 1963. Vegetation and soils. A world picture. London. Edward Arnold (Pübl.) Ltd. GILE, I. H., PETERSON, P.P. and Grossman, R.B. 1965. The K horizon: a master soil horizon of carbonate accumulation. Soil Sei. Vol. 99, No 2, p. 74. GOOSEN, D. 1967. Aerial photo interpretation in soil survey. FAO. Rome. Soil bulletin no 6. GROB, A. 1896. Beitrage zur Anatomie der Epidermis der Gramineenblätter. Bihl. Bot. Heft 36. Lieferung 1 und 2. GUEST, E. R. 1966. Flora of Iraq. Volume one. Introduction to the flora. Publ. by the Min. of Agric. of the Rep. of Iraq. HALLSWORTH and CRAWFORD (editors) 1965- Experimental pedology. London.- Butterworths. HARE, P. K. 1961. The causation of the arid zone. Arid Zone Res. XVII. A history of land use in arid regions. Unesco, p. 25 • HEINRICH, E. Wm. 1965. Microscopic identification of minerals. Me Graw-Hill book Company. HILGARD, E. W. 1910, Soils. Their formation, properties, composition and relation to climate and plant growth in humid and arid regions. New York. The Mac Millan Company. HOEKSEMA, Ir. K. J. 1959« Bodemfauna en profielontwikkeling. Bodemkunde. Voordrachten B-cursus. Min. v. Landbouw en Visserij, p. 28. ISRAELSEN, 0. W. and HANSEN, V. E. 1962. Irrigation principles and practices. John Wiley and Sons, Inc. London. JACKSON, M. L. 1956. Soil chemical analyeie-Advanced course. Printed in U.S.A. JENNY, H. 1941, Factors of soil formation. Me Graw-Hill Book Company, Inc. New York and London. JOPPE, J.S. 1949. Pedology. Pedology publ. New Brunswick, New Jersey. JONGERIUS, A. 1957. Morfologische onderzoekingen over de bodemstructuur. Bodemkundige studies no 2, Wageningen. JONGERIUS, A. 1959. De morfologie van de structuur. Bodemkunde. Voordrachten B-cursus. Min. v. Landbouw en Visserij, p. 76. JONGERIUS, A. and HEINTZBERGER, G. 1962. The preparation of mammoth-sized thin sections. Soil survey papers no 1, Wageningen. KELLER, W. D. 1958- Argillation and direct bauxitization in terms of concentrations of hydrogen and metal cations at the surface of hydroliaing aluminum silicates. Bull, of the Amer. Ass. of Petr. Geol. Vol. 42, nr 2. KELLEY, W. P. 1951- Alkali Soils. Their formation, properties and reclamation. Reinhold Publ. Corp. New York. KELLEY, W. P. 1964. Review of investigations on cation exchange and eemiarid soils. Soil Sei. Vol. 97. p. 80. KERPEN, W., GEWEHR, H. 4 SCHARPEHSEEL, H. W. i960. Zur Kenntnis der Ariden Irrigationsböden des Sudan. II Teil. Pédologie X 2, s. 303. Gent. KERR, P. P. 1959. Optical mineralogy. Mc Graw-Hill Book Comp. London.' KEHR, P. F. 1937- Attapulgus clay. J. of the Min. Soc. of America. Vol. 22. p. 534. K0N0N0VA, M. M. 1961• Soil organic matter. Pergamon press. London. KOPP, E, 1965* Die Permeabilität durchlässiger Boden, die Gliederung des Makroporenraumes und die Beziehungen zwischen Permeabilität und Bodentypen. Zeitschrift für Kulturtechnik und Flurbereinigung. 6 Jahrgang. Heft 2, e. 65. KUBIENA, ¥. L, 1958. The classification of soils* The J. of Soil Sei. Vol. 9. KUBIENA, W. L. 19^4* Role and mission of micromorphology and microscopic biology in a modern soil science. Soil Micromorphology edit. Jongerius. Elsevier Publ. Comp. A'dam. KUENEN, Ph. H. and PEHDOK, W. G. 1962. Experimental abrasion 5. Frosting and defrosting of quartz grains. The J. of Geol. Vol. 70. No 6. LANG, Prof. Dr. R. 1920. Verwitterung und Bodenbildung als Einführung in die Bodenkunde. E. Schweizerbart'sehe Verlagsbuchhandlung. Stuttgart. McINTYRE, D. S. 1958. Permeability measurements of soil crusts formed by raindrop impact. Soil Sei. Vol. 85. p. 185. McINTYRE, D. S. 1958- Soil splash and the formation of surface crusts by raindrop impact. Soil Sei. Vol. 85. p. 216. MEIGHS, P. 1962. Classification and occurrence of Mediterranean-type dry climates. Arid Zone Res. XXVI. Unesco. MILNER, H. B. 1962. Sedimentary petrography. George Allen & Unwin Ltd. London. MOHR, E. C. J. and VAN BAREN, F. A. 1954. Tropical soils. N. V. Uitg. W. van Hoeve-The Hague and Bandung.

194 HOUTERDE, P. 1966. Nouvelle flore du Liban et de la Syrie. Edit de L'Impr. Cath. Beyrouth. MUIH, A. 195I. Notes on the soilß of Syria. J. of Soil Sei. Vol. 2. p. 163. NETOLITZKY, Dr. F. 1929. Die Kieselkörper. Handb. der Pflanzenanatomie. Band Ill/la. Berlin. Verl. von Gebr. Borntraeger. PAMIR, H. N. 196O. Turquie. Lexique Stratigraphique International. Volume III. Asie. Fascicule 9 c. PAPADAKIS, J. 1961. Climatic tables for the world. Buenos Aires. Edited by the author. PARFENOVA, E. I. and YAHILOVA E. A. 19°2. Mineralogical investigations in soil science. Israel Progr. for Scient. Transi. Jerusalem 1965- PERBIN, DE BRICHAHBAUT, G. et WALLEN, C. C. 1964. Une étude d'agroclimatologie dans les zoneB arides et semi-arides du Proche-Orient. FAO/Unesco. OMM-no 141 - T. P. 66. Mote technique no 56. PETTLJOHN, F. J. 1957« Sedimentary rocks. Harper à Brothers. Hew York. POWERS, H. C. 1953. A new roundness Bcale for sedimentary particles. J. of Sedim. Petr. Vol. 23. no 2. p. 117* RADOSLOVICH, E. V. 1958. Clay mineralogy of some Australian Red-Brown earths. The J. of Soil Sei. Vol. 9« London. REIFENBERG, A. 1947. The soils of Palestine. London. Thomas Hurby * Co. BEYNDERS, J. J. 1964. A pedo-ecological study of soil genesiB in the tropics from sea level to eternal snow. Star mountains. Central New Cuinea. Proefschrift Utrecht. REYNDERS, J. J. 1964. Toepassing van röntgenspectrografie in de bodemkunde en geologie. Chemisch Weekblad. No 2. Deel 60. REYNDERS, J. J. 1966. Brown soils of the semi-deaert region in Syria. Conf. on Medit. Soils. Madrid, p. 43- RICHARDS, L. A. 1954« Diagnosis and improvement of saline and alkali soih. U. S, Lab. Staff. Agric. Handb. nr. 60. RICHTER, P. 1967. HöntgenBpektrometrische Bestimmung von KgO und CaO an GesteinBstandards-ein Beitrag zur Aufschlusstechnik. Z. Anal. Chemie, 233 (5)» s- 340. RINALDI, F. F. and AQURZI, P. E. 1966. A simple technique for casting glaBs disks for X-ray fluorescence analysis." Spectro- cbimica Acta, 1967» Vol. 23 B, p. 15. RODE, A. A. 196I. The soil forming process and soil evolution. Israel Progr. for Scientific transi. Jerusalem. ROQUERO DE LABABU, C. et ONTANON SANCHEZ, J. H. 1966. Une forme d'accumulation des carbonates c&lcique et magnesique en bandée horizontales et grillages sous climat semiaride Méditerranéen. Conf. on Medit. Soils. Madrid, p. 463. ROSENAN, N. 1963. Climatic fluctuations in the Middle EaBt during the period of instrumental record. Arid Zone Res. XX. Changes of climate. Unesco, p. 67. BUSSELL, E. W. 1950. Soil conditions & plant grovth. Longmans, Green and Co. London. SCHARPENSEEL, H. W., GEWEHR, H. & KERPEN, W. i960. Zur Kenntniss der Ariden Irrigationsböden des Sudan. I Teil. Pédologie X, 2, s. 291, Gent. SCHEFFER, F. und SCHACHTSCHABEL, P. i960. Lehrbuch der Agriculturchemie und Bodenkunde. Ferdinand Enke Verlag. Stuttgart. .SCEILSTRA, Ir. J. 1963- Nieuw kleed voor een oud land het Eufraat-project. Tijdschrift Heide Mij 74. p.199. SIMONS, M. 1967. Deserts. The problem of water in arid lands. Oxford Univ. Press. SINGER, A. and RAVIKOVITCH, S. 1966. The nature and properties of basaltic soils in Israel. Conf. on Medit. SOÜB. Madrid. SMITH, R. and ROBERTSON, V. C. 1962. Soil and irrigation classification of Bhallow soils overlying gypsum beds. Northern Iraq. The J. of Soil Sei. Vol. 13. Oxford. SMITH, G. D. 1965. Lectures on soil classification. Pédologie spec, nr 4. Belg. Soil Sei. Soc. SMITHSON, F. 1956. Silica particleB in some British BOÜB. The J. of Soil Sei. Vol. 7. SMITHSON, F. 1958. Grass opal in Britißh soils. The J. of Soil Sei. Vol 9. STACE, HUBBLE, BREWER, NORTHCOTE, SLEEMAN, HULCAHY and HALLSWOHTH.1968. A handbook of Australian soils. Publ. by Rellim Techn. Publ. Glenside. S. Austr. STREBEL, 0. 1965. Bodengesellschaften Syriens und des Libanon. Geol. Jb. 84, B. 1. TACKHOLM, V. 1956. Students flora of Egypt. Publ. by Anglo-Egyptian Bookshop. Cairo. THORNBURY, W. D. 1954. Principles of geomorphology. New York. John Wiley & SonB, Inc. THORNTKWAITE, C. W. 19^8. Introduction to arid zone climatology. Arid Zone Res. XI. Unesco. TWENHOFEL, W. H. I96L Treatise on sedimentation. Vol. 1 and 2. Dover Publ., Inc. New York. TYßREL, G. W. 1956. The principles of petrology. London. Methuen & Co. Ltd. VAN ALPHEN, J. G. 1968. Some notes on gypsiferous soils and their management. Int. Inst. for Land Reel, and Impr. Bulletin 11. Wageningen. VAN ANDEL, Tj. H. 19^0. Provenance, transport and deposition of Rhine sediments. Proefschrift Wageningen. VAN BAREN, F. A. 1934- Het voorkomen en de betekenis van kali-houdende mineralen in Nederlandse gronden. Proefschrift Wageningen.

195 VAN BAREN, Dr. P. A. 1938. Doel en methode van bet röntgenografiach klei-onderzoek. Landbouw XIV. p. 659. VAN BAREN, P. A. and Kiel, H. 1956. Relationship between the mineralogical composition and fertility of tropical soilß. Vine Congres de la Sei. du Sol. PariB. p. 197. VAN LIEHE, U. J. 196O-I96I. Observations on the Quaternary of Syria. Bepr. from the Berichten v. d. Bijkedienst voor het Oudheidkundig Bodemondersoôk. Jrg. 10-11. p. 7* VAN LIBRE, V. J. 1962. The arid Boils of the Near East. Their morphology, classification and utilisation. First soil corr. Bern, for South and Central Asia. Tashkent, Uzbekistan, U.S.S.H., FAO. VAN LIERE, W. J. 1964. Soil map of Syria/scale 1(500.000. Damascus. VAN LIERE, W. J. 1965. Classification and rational utilization of soils. Rep. to the Govern, of Syria. FAO, Rome. VAN HUMMELEN, F. H. 1942. Bijdrage tot de kennis van bet ontstaan der loessoïden. Jaarverslag 1940-1941. Oeol. Bur. Heerlen. VAN HUMMELEN, F. E. 1945* Het korrel be e ld van de loss uit het Rijngebied, de loss leem en de zandige IÖBS, vergeleken met dat van Zuid-Limburgsche losBoïdsn in het driehoeksdiagram. Verb. v. h. Geol.-Mijnb. Oen. voor Ned. en Kol* Oeol. Ser. deel XIV. VAN RUMMELEN, F. F. F. E. 1948. Magmatische corrosie van pyroxenen. Gaol, en Mijnb., no 11, p. ?00. VAN RUMMELEN, F. F. F. E. 1950. Enkele aantekeningen bij relictatructuren van mineralen. Qeol. en Mijnb. mei 1950, p. 140. VAN RUMMELEN, F. F. F. E. 1951. Aanvullende aantekeningen omtrent magmatische corrosie verschijnselen. Qeol. en Mijnb. mei 1951, p. 1. VAN RUMMELEN, F. F. F. E. 1953. The mineralogical importance of "organic SiO " in the soil. Landbouw nr 25. p. 225. Djakarta. VAN SCHUYLESBORGH, J. and SÄNGER, A. M. H. 1950. On the origin of clay minerals in the soil. Landb. K. tijdschr. 62ate Jrg. no 4/5- VEENENBOS, J. S. and GHAITH, A. M. 1964. Some characteristics of the desert soils of the U.A.R. 8th Int. Congr. of Soil Sei. Bucharest. VOUTE, C. and WEDMAN, E. J. 1963. The Quaternary climate as a morphological agent in Iraq. Arid Zone Res. XX. ChangeB of Climate. Unesco, p. 395. WHYTE, R. 0. 1961. Evolution of land use in South-Western Asia. Arid Zone Res. XVII. A hißtory of land use in arid regionB. Unesco, p. 57* VIERSMA, J. 1966. Electronenmicroscopisch onderzoek van grondmonsters afkomstig van het Euphrates Project in Syrië. Interne communicatie Fyaisch-Oeografisch Lab. G. U. A'dam. WOLFART, R. 1966. Zur Geologie and Hydrogeologie von Syrien. Beihefte zum Geologischen Jahrbuch. Heft 68. ZOHARY, M. 1966. Flora Palaestina part one. The Israel Acad. of Sciences and Hum. Jerusalem.

. ALPHABETICALLY ARRANGED ACCORDING TO TITLE. DEFINITIONS OF SOIL UNITS TOR THE SOIL MAP OF THE WORLD. 1964. FAO, Rome. DIAGNOSIS AND IMPROVEMENT OF SALINE AND ALKALI SOILS. 1954- U. S. Salinity laboratory Staff. Agric. Handb. nr 60. Washington. IRRIGATION AND DRAINAGE PROJECTS IN THE EUPHRATES BASIN. Phase I and II. Report Balikh Basin 1966-1967. Consulting Engineers Sir Alexander Gibb &. Partners (London) and F. H. Kochs K. 0. Ingenieure (Koblenz). PRELIMINARY DEFINITIONS, LEGEND AND CORRELATION TABLE TOR THE SOIL MAP OF THE WORLD. 1963. FAO, Rome. REPORT ON THE INVESTIGATIONS IN THE EUPHRATES PROJECT AREA, part I and II. 1963. Nedeco. Netherlands Eng. Cons., The Hague. SOIL CLASSIFICATION. A COMPREHENSIVE SYSTEM. 7th APPROXIMATION. 1960. U. S. Dept. of Agric. SOIL MAP OF THE NKAR EAST. 1963. Prov. expl. note 00844, FAO, Rome. SOIL SURVEY MANUAL. 1951. Soil Survey Staff. U.S. Dept. of Agrio. Handb. 18. SUPPLEMENTS TO SOIL CLASSIFICATION SYSTEM (7th APPROXIMATION) 1964, 1967. U.S. Dept. of Agric. THE OEOLOGICAL MAP OF SYRIA. 1963. Scale 11200.000. Sheet Ar-Rasafah, sheet Ar Raqqa, sheet Jrablus, sheet Tuwal al Aba. Technoexport. Moscow. U.S.S.R. X-RAY POWDER DATA FILE. 1962. Minerals Section, American Soc. for Testing and Materials. Philadelphia.

"196 CURRICULUM VITAE

De schrijver van dit proefschrift behaalde in 1958 het diploma H. B. S. B aan het Moller Lyceum te Bergen op Zoom. De studie in de geologie werd in hetzelfde jaar begonnen aan de Rijksuniversiteit te Groningen. Het candidaats- examen (Wis- en Natuurkunde i) werd aldaar in september 1961 met succes afgelegd. Het doctoraal diploma (hoofdvakken bodemkunde en geologie, bijvak sedimentologie) werd behaald in juni 1966 aan de Rijksuniversiteit te Utrecht. Gedurende de periode februari 1965 tot mei 1966 was de schrijver werkzaam als bodemkundige aan het Eufraat Project in Syrië. Na terugkomst volgden werkzaamheden als leraar in de biologie en scheikunde aan het Möller Lyceum te Bergen op Zoom gedurende het studiejaar '66-'67. Vanaf september 1967 was hij als assistent verbonden aan hetBodemkundig Instituut van de Rijksuniversiteit te Utrecht.