Geology of the Wajir-Wajir Bor Area

Report No. 5"?57

GOVERNMENT O}?OF KENYA

MINISTRY OF COMMERCE AND INDUSTRY h GEOLOGICAL SURVEYSERVEY 0FOF KENYA

If GEOLOGY !I OF THE Ii WAJIR~WAJIRWAJIR—WAJER BOR AREA i! (with two coloured geological maps)

DEGREE SHEET 31, NSF“N.E. and "NJ-V.N.W. QUARTERS

by P. JOUBERT, M.Sc.MSC. GeologistGeelogist

f Fifteen ShiShillingsﬂings - 1963 i

.. - - . -" 1

FOREWORDFOR EW'OR l) The publication of the report on the Wajir-Wajir Bor area completes the first reasonably detailed exposition of the geology of the visible Mesozoic basin of north—eastnorth-east Kenya. The basin lies east of the 40th meridian and north of the 1°10 30’30' N. parallel; previous reports numbered 40.40, 43.43, 44.44, 47‘47 and 48 have dealt with other sections. The Mesozoic rocks are exposed to only a small extent north-east of Wajir in the area now described.described, the rest of the area being covered by much younger rocks. The geology is difdifficultﬁcult to unravel in such featureless country.country, but Mr. Joubertloubert has succeeded in deciphering an intelligible succession. He shows thatthat what have been considered previously as Tertiary sediments are in fact Quaternary.Quaternary, though he appreciates that 'l'ei‘tiaryTertiary rocks may well exist.exist, at depth. Facts are put forward that show that in the southern part of the area the depth of.of Quaternary sediments is considerable, and suggest that still further south the eontinuationscontinuations of the Mesozoic rocks may be buried at great depths below younger reeks.rocks. Water—supplyWater-supply is an important consideration in such an area.area, and some attention is given to it in the report. Mr. Joubei‘tJoubert discounts a suggestion that has been made previ—previously that the water—tablewater-table is dropping at a rapid rate.rate, pointing,pointing out that the wells there have not been deepened by the present inhabitants who began to live in the country some 50 years ago.ago, and yet they still contain several feet of water.

Nairobi,Nairobi. WILLIAM\-\-"|l.l.IAI\-'l PULFREY.PULFREY, 21stlt January,January. 1959. Ale.Ag. C'rimm."_\'.l'."mt<’rCommissioner (Mines and Geology).

. CONTENTS PAGEPA GE Abstract

I-Introduction.l—lntroduction . .

1.I. General InformationInformation

2. Previous Geological Work 2In)

II-Physiography|i.--—P]1ysiogrtiphy 3'uJ

III-SummaryIl [--—Sun1m;1r§.' of Geology 3IJJ

IV-Details[Vi—Details =11"of GeologyGeology. . 44::-

1. MamaMansa (EudztGuda Formation 4.45.

2. .DtsutiDaua limestoneLimestone Series 4 (a) Didimtu Beds 7 (1‘1)(b) Bur Mayo.‘Vlayo Limestonesl .hestoncs . . . 10I0 (t)(c) Structures in1n the Jurassic Limestones1. imcstones 15[5

3. QuaternarvQuaternary Sediments 19[9 (a) Wajir\V111r Beds . . 19IL) idsiones EJ“‘.£l. conglomerates (b) Ferruginous sandstones and conglomerates 252. (c) Thin laminated{’1 limestones.iimestones . _. 26 (d) Grey and black‘k gsittvgritty soilssoils. . . 26 (e) Red—Red-brown01 andd yellowish,eilowis‘n brown clawsclays 2727' (2‘)(I) Red and grey SOllSsoils. . 28 (g) ValleyVaillt-._ soils '.. 28 ‘1-’—{.":ee:.1!ogicalV-Geological History..History 28 VI-Mineral\-"I—'_\.fli;‘.e;;:_i DepositsDeposits 29 1. Oilmg] . . . . 29 2. Building”ltiing MaterialsMaterials. . 30 3. WaterVV-"zIIEr 30 VII-ReferencesVII—References 33

LIST OF ILLUSTRATIONS Fig. I.-Sketch-mapl.—---Sketcl1-map illustrating the distribution of sediments of the Wajir-WajirVV" '1j i r --\V"t1j i r Bor area . . . . . 5 Fig. 22.-Structural.—Strueturt1l map of the Jurassic limestoncslimestones . . 16 Fig. 3.—Ske-tch—plans3.-Sketch-plans of structures.structures in the Jurassic.lu1assic limestones. . 18

MAPS Geological map of the V'wajirWajir area (degree sheet 3i,31, N.W.)-ScaleNW.) —Scale 1:125,0001125.000 ... At end Geological map of the VVWajirajir Bor area {dcgrce(degree sheet 31, N.E.}--—ScaleN.E.)-Scale 1:125,0001:125,000 ... At end

~ r

ABSTRACTA BS’l‘R ACT

The area described in the report covers approximately 2,4002.401) square miles of the district of Wajir.Wajir, in the Northern Province of Kenya Colony, and is bounded by{1'- latitudes 1°l' 30’30' and 2°2" 00' N.,N, longitude 40°4U" 00't'ttl' E.,13.. and the Kenya—SomaliaKenya-Somalia border. The oldest rocks exposed are of Jurassic age and consist of limestones deposited in a neriticnei‘itie marine environment,environment and bevelled by two surfaces of Tertiary age. The remainder of the area is occupied by limestones‘limestones, "ypsum,gypsum, sandstones and clay—boundclay-bound sands depos...eddeposited in laeustrinelacustrine and t-alleyvlletvalley-flat environments during Pleistocene times. Deposits that may beeomebecome ot‘of eeonomieeconomic value when the area is developed or oil is discovered (a possibility whichwhieh is also discussed],discussed), are described. Consideration is given to the imprtwetrientimprovement allof present \t-‘a'ter—supplies.water-supplies.

i::"-'-';'1!!!!!' ~ ~- :=: =-'..==- ~ .. I-INTRODUcrIONI—INTRODUCTION

1. General Information

The area to be described in this report is bounded by the Kenya—SomaliaKenya-Somalia border on the cast,east, and lies between latitudes 1l”° 30’30' N. and 2° N,N., extending as far as longitude 40°40" E. on the west. itIt comprises the north-east and north-westnorth—west quarters of degree sheet 3!31 (Kenya) (Sheets 72 and T373 of the Directorate of Overseas Surveys). The area, which is part of.of the Wajir administrative district of the Northern Province.Province, is a closed district under the Outlying Districts Ordinance (Proclamation No. 89 of 1925).I925). The area is mainly inhabited by Somali tribesmen of the Degodia and Ogaden sections.sections, between whom the wells and grazing rights are divided. For most part of the year the population is centred on the wells of Wajir.Wajir, but.but during and alterafter the rainy seasons the inhabitants, who are nomadic, are sparsely scattered over the whole area. Wajir is considered to be the main administration centre of north—easternnorth-eastern Kenya and is connected to lsioltnIsiolo, Moyale.Moyale, ElEI Wak.Wak, Melka Murri and Bardera (in Somalia) by roads which are reasonably good in parts. Several of the larger camel tracks, of which zit-anymany cross the areaarea, were most usefulLiselul in trave.traversinging and mapping. 'l'hereThere is a motorable track from Wajir Bor to Riba and Balballa.Balballa, which carries on to the north—easternnorth-eastern corner of the area and eventually linkslinks up with the border—cutborder-cut to thethe north of thethe area, which can also be used by smaller vehicles. The old road from Wajir through EEI 'I‘uiiTuli joins the road to Bardera at Khorof Atat.Atat, Another motorable track from 'Wajir,Wajir, passing through Uhia and Berrer Bahar.Bahar, eventually joins up with the track from ElEI 'l'uli.Tuli through Khorof Sharif and Gemhis.Gembis. The old road from ElEI Tuli to Dif is also motorable for a long distance to thethe south, but is now inin disuse. Wajir is in communication with Isiololsiolo and Nairobi by radio, the Administration using the service supplied by the Posts and Telegraphs Department.Department, while the Police keep in touch with their outposts by the same means. The medical officeroliicer for the whole of the Northern Frontier District isis stationed at Wajir.Wailr.

MAPSHA PS

For convenience the results of the mapping of the area are presented as two geo—geological mapsmaps-thethe Wajir sheet and the Wajir Bor sheet. In the account that follows the area covered by the two quarter—degreequarter-degree sheets is treated as a whole. The geological maps are based on aerial photographs,photographs. the scale otof which is approximately 1 2: 30,000,30,000. Ground control was provided by data from geological maps of the areas to the north.north, fiverive astronomically determined points, two of which are just south or“of the area, and a survey olof the main roads. The form—linesform-lines are based on barometer readings and are therefore approximate only. CLIMATE AND VEGE'J‘A’I'IoNVEGETATION Rainfall over the area is low, as shown by the following raintallrainfall figures for Wajir:Wajir:- -—

Year .. 1950 19511951 1952 1953 19541954 j 1955 --. ..[ 0 {Sam[nches .. I 6'976-97 220.23‘23 9449,44 14.02i402 i TS?7'87 4-434'43 "I I

The average rainfall recorded over 29 years is 8.758.??? in. The maximum rainfall occurs during April and May, the heavy rains sometimes stainingstarting as early as mid—March.mid-March, while localizedlocalized showers failfall during the months of October and November. During the rains no vehicular traftrafficﬁc isis allowed through the area in order to protect the surfaces of the roads. 2

Limestones in the area are usually covered by dense low thorny”thorny scrub.scrub, while red sands are usually covered by dry open bush with clumps of larger trees and bushes in depressions. Grey soils carry a similar vegetation to the limestones,limestones. but where black soils occur trees and scrub are often absent and the only vegetation is tufts of rough grass. On the grey soils the bush often opens and surrounds circular glades for no apparent reason. '1Thickerhicker thorn scrub and low trees usually follow the dr}dry water courses.

2. Previous Geological Work

In a description ofof. the country betweenbetveert the Juba.luba river and Lake Rudolf,Rudolf. Lt.l.t. L.l.. Aylmer *(l9ll,*(1911, pp. 293-294).293-294), described the area known as WaiirWajir (\ll-"ajeirt(Wajeir) as having numerous wells cut straightstraight. down in solid rock and dedtteeddeduced correctly that a more industrious tribe than the present inhabitants was responsible for the digging ofoi" the wells.Wells. He recorded that the mouths of the wells were 36 to 40 in. across and that the water was 22 to 2928 it.ft. below the surface. He considered the water from the wells "very wholesome as a blood purifierpuriﬁer and febrii'ugc"febrifuge" with only the slightest chemical taste. He erroneously assumed that the piles of rock occurring in the neighbourhood were ofoi igneous origin.

- During July and August, 1912,I912. C. W'.W. Haywood ([913),(1913), marched Fromfrom KisrnavoKismayo to Meru in an cll'orteffort to discover whether the LiasoVaso Nyiro ﬂflowsows out of the Lorian Swamp. He passed through E]El 'l'uliTuli (Eil 'l‘uli.Tuli, op. r-it..cit., p. 466]466) and described the wells there as being only about 6 ft. deep=deep, and dug in “a"a kind of grey sandstone".sandstone", the water being strongly impregnated with sulphur,sulphur. Twenty miles from El 'l‘uii.Tuli, at Siddeh Dima,Dime. a Government post had been opened and Haywood (op. cit., p. 466) recorded that a large number oi;of wells had been dug to a depth of 20 ft.it. or so in "a soft.soft kind of gypsum rock" overlain by 2 ft. or more orof a reddish sand. He also mentioned the cairns of rocks described by AylmcrAylmer as of igneous origin and correctly assumed them to be graves of the people who originally dug the wells otof Wajir.

J. Parkinson (1920')(1920) travelled through the Northern Frontier District andand .lubalanciJubaland in 1914l9l4 examining the geology. He devoted much space to the palaeontologypalacontology and geology of the El Wak and Wajir (Wajhir) Beds. In a later paper (Parkinson, 1922),1922']. he again mentioned the wells of Wajir as situated onon the sitesite of.of anan old lake.lake.

H. G. Busk and J. P. de Verteuil (1938')(1938) visited the north-easternnorth—eastern part oiof Kenya on behalf of the D'ArcyD‘Arcy Exploration Co. Ltd. and Anglo-SaxonAnglo—Saxon Petroleum Co. and carried outout. a rapid reconnaissance. They errmteouslyerroneously considered Cretaceous sandstones as horsts of pre-Jurassicpro—Jurassic rocks that stood as islands in the Jurassic sea,sea. and assumed that II thethe, Wajir Beds were intercalated with the Jurassic limestones (Bush.(Busk, 1939.1939, pp. 220-221).EEO—ZEN. Ii F. Dixey (1948.(1948, pp. 9—12)9-12) in a description of the geology and morphology of northern Kenya, devoted a chapter to the post-Jurassic sediments of the Northern Frontier District and came to the conclusion that the bulk of the sediments belong to the Tertiary. F. M.M, Ayers (1952.(1952, pp. 15—16).15-16), in agreement with Dixey.Dixey, tentatively ascribed a Tertiary age to the Wajir and El Wak Beds inin hishis description of the geology of the Wajir-Mandera District.

Since 195.31953 the north—easternnorth-eastern part of Kenya has hecnbeen re—mappedre-mapped in detail by geologisgeologistss of the Geological Survey of Kenya (Saggerson and Miller,M iller. 1.957;1957; 'l'hompsonThompson and Dodson.Dodson, 1958; Baker and Saggerson.Saggerson, 1958'.1958; Thompson and Dodson.Dodson, 1960; Jeubert.Joubert, 1960)i960] and the present report concludes the work on the exposed .‘-'iesozoicMesozoic sediments of that partpart. of the country.

*Rcfereitces'References are quoted on p. 33.

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., 3.1

n--;PHYSIOGRAPHYII—PHYSIOGRAPIIY The‘l‘he Wajir\\-“:1ji1' area can be divided into twotvvo physiographicphtsfographie regions:reLigoris: {ll(1) The north- central portion underlain by limestoneslit testones ol‘of .lura'JurassicL‘ age,age. whereuhete remnantsLezrtnanis ofot‘ surfaces5urfaees representing stable periods during Tertiary‘l‘ertiarv times are found and (ii) the remainder of the area.area, which“hi-eh isi5 aEL wide\vide undulating plain ofot‘ Pleistocene sediments. When the physiographicphvsiogi‘aphie maps11 ans ofot‘ the Bur lN'la‘L-o—Mayo-TarbajTat'baj (Thompson and Dodson,Dodson. 1960,5160 fig. 2)2] and‘1“dji"““the EIE! Wak-Aus\N‘LtiL—Aus Mandula.\.l-L1ndula (Baker[Ba 1.1T and Saggerson,SL-iggerson. 195.51958,. hgfig. ll1) areas are studied,stud: L.L'l it is 5eL-11seen that the equivalent Eriblirih and MugudaMneuda surfacessittt‘aL‘L's extend into.-n‘Lo the north-central ' ‘t‘jartpart ofot‘ the present area.'1rea. Furthermore,l-‘1.irtl‘.er:11ore. Thompsonlhon'tpson and Dodson to(op..’J. cit., p. 4) state.-L that the .5"L1.rl"L'L-L‘esurface 5lopL15slopes down to ELa leteilevel of 1,200LIP-{l ft.it. where i'-.it ehier5enters :hethe present area.area, and thereforetrhe'et‘ore the tops 01‘of the two hills at (jajajaGajaja represent remnants:‘eitirt'Lt:1:5 of this hevei.bevel. The high ground to the east oi.of G:j1:1j:1Gajaja would\vo‘tltl then 21l5o|also form.orm 31a 5011112131.}somewhatat denuded part oi"of thethe 5'LL111L:same bevel,hov-Ll. whichultieh is taken to rept'L5entrepresent the maturation oiof an1erosio1ialerosional phaseohase betweenb-Lttxxeen those that culminated with the formation of end—tertiaryend-Tertiary and sub-Miocene.511.— \lioL‘ene 5‘Lirl:;L‘_‘5.surfaces. FromT-‘;‘om these northern ei'elevationsevati ("is the sur‘etasurfacee on the Jurassic lmLstolimestones1'15 slopslopeses down it}to the cats:east to meet the end—Ierttar}end-Tertiary oenep‘tai‘peneplain,11 Lshi‘ehwhich beveisbevels the southemsouthern part,att ol‘of the limestone outcrop. The.The Slopeslope of this .5'1Ltrla'L‘esurface orof 10 ft.it. per mile :0to the south—southeastsouth-south-east LLsas deseriheddescribed in}by Baker and SaggerscnSaggerson it‘lFS.(1958, p.11-. St5) fort'1r the area to the north.north, is also :teredadhered to on the .lnrassieJurassic limestones here. The end—Tend-Tertiaryertiary peneplain eancan be recog-recog— nized by the presence of numerous l‘erz‘uginousferruginous pellets 5t2‘eWnstrewn on the surface.surface, as is the easecase in the .‘11Manderader'Lt area [J1(Joubert,Jtzhert. 11160..1960, p. (11.6). The.The t‘errugtferruginous pellets are also found on the toi15tops ol‘of the mounds of material derived from wells piereingpiercing the Pleistocene deposits at Riha.Riba, wheretvhere theythe}; are l-tnounknown to be at leastie'. 5t —ltl40 ft.it. thick.thick, ind‘L'aindicatinging the depth below surt‘aeesurface oi"of the end-‘l‘ertiarvend-Tertiary sttz‘t‘aeesurface at this locality.localit}. On the vvestL.:‘11western tlankflank ot"of the outcrop of the lurassieJurassic lin'1e5ion-L15limestones the end—Tertiaryend-Tertiary peneplain “aswas only encountered at ForogorgorFnrogorgor where it conforms with the 11'generaleneral slope oi“of the bevel. Along the \vesierhwestern side of the Jurassic limestones.limestones, however.however, three \vellmtarketlwell-marked terraces. aces wereoere found above the end-Tertiaryend—‘l‘ertiart' peneplain.penepiain. ‘I‘hL:The twotu'o lower terraces,terraces. the lowestIoLLest ofoi‘ which occurs 35.25 ft.it. above the end—Tertiaryend-Tertiary surface at ForogorgorI-“oroeorgor and 20 ft.it. below the middle terrace,terrace. are marked by sui‘t‘aeesurface li:‘nestonelimestone cap-pings.cappings, but the upper,upper. 30 ft.it. higher than the middle terrace,terrace. has numerous waterwornvvatervvorn pebbles on itsits surl‘aee.surface. ‘l‘heThe pebblesneh‘nles ot‘of this upper terrace in the Gajaja area have been derived from Basement .51Systemstern and litraJurassic.55iL‘ rocks,rocks but further south onlvonly limestonesiimestones pepebbleshb'es are encountered. Thesethese 1eterracesraces are thought to have been formed during stable phases in Tertiarylertiaty times when Lta deep \alleL-valley \va5was formed{L11 med to the west\ 'est and south—nestsouth-west of the Mesozoic sediments. DixeyDixev 119—18.(1948, l'ig.fig. I.)1.) shows the surface at Wajir as part of the end—Tertiaryend-Tertiary peneplain,plain. :1a view that Thompson and Dodson{liaison H960.(1960, p. 6)(it conconfirmed.ﬁrmed. During the present survey,5ttr\ev. however,however. it was foundFound that the 5edin'1entssediments at Wajir\V‘ajir are.are of Pleistocene age and therefore that the sttrt‘aeesurface is younger than at first supposed. The plain of Wajir slopes evenly at 141—1 ft. per mile to the .so'Ltth—south—eastsouth-south-east and is only slightly undulating.undulating, with wide shallow Llrain2111evallev5drainage valleys hardly noticeable when traversed. All the drainage channels of the area lead south to Lugh Bor which eut5cuts aernssacross the south-western corner of the area.area and it is onlvonly along the southern border of the area that recentreeent dissection of the Pleistocene deposits oecurs.occurs. Ridges of limestone forming undulations inin the Wajir Beds rise slightly above the general level of the plain,plain. whitewhile shallow braided channels.channels, hardly noticeable on the ground.ground, are seen on the aerial photographs.

m-SUMMARYIII—uSUMMARY OF GEOLOGY The rocks of the Wajir area are all of sedimentary origin and range in age from Triassic to Recent. Three divisions can be recognized:-recognized:— (3l(3) Quaternary sediments (2](2) DauaDana Limestone Series (1) MarisaMansa Guda Formation.

I J I I -

I II 4

The Mansa Guda Formation is not.not, in fact,fact. exposed in the area.area, but quartziticquartzitie boulders and pebbles derived from its conglomerates indicate the position of thethe southerly exten—extension from the area further north of these arenaceousarenaeeous sediments under the soil cover. The DauaDatta Limestone Series in this area consists of a lower fossiliferous limestone succession of 'l‘oarcianToarcian age which is an extension of the Didimtu Beds of thethe area further north,north. overlain conformably by a series of brown and grey fragmentalfragmented argillaee—argillaceous or finelytinely recrystallized limestones of Bathonian-CallovianBathonian—Calio\.‘ian age.age, which are equivalent to the Bur Mayo limestones oiof the Bur Mayo-Tarbaj area (Thompson and Dodson.Dodson, 1960,1960. p. 24).2—11. The series was deposited in a shallow marine environment and was faulted along north-easterlynorth—easterly striking zones and slightly folded along the strike during the Cretaceous period. l-ixtensiyeExtensive continental erosion during the Tertiary era gave rise to the formation of a wide deep valley west and south of the area occupied by the Mesozoic sediments.sediments, but the valley was ﬁfilledlled up during the Pleistocene by limestones and gypsum of iacustrinelacustrine origin and by clay-bound sands and sandstone of ﬂfluviatileuviatile origin. These Pleistocene deposits are representatives of the pluyialpluvial phases of the period while the widespread red sandy soil of Wajir has been deriyedderived from red ferruginous sandstones indicatiyeindicative of an interpluvial stage. Fig. 1 demarcates the distribution of the sediments in the \VajirWajir area. Table 1 summarizes the stratigraphical succession and indicates the major events contributing towards the deposition of the sediments.

IV-DETAILS[V'uDETAlLS OF GEOLOGY 1. ManseMansa Guda Formation Ayers (1952.(1952, p. 6!6) fifirst"rst described the Mansa Guda Formation.Formation, dedefiningfining it as sand—sandstone-conglomerate beds at the base of the Jurassic limestones and came to the conclusion that it is of Lower Jurassic age or older. Thompson and Dodson (1960.(1960, p. 15) compared the Mansa.‘V‘lansa Guda Formation with the Adigrat Sandstones of Ethiopia (Dacque(Dacqué and Krenkel,Krenkel. 1909,1909. p. 152) and with thethe Lugh Group in Somalia (Stefanini.(Stefanini, 1925,1925. p. 1.061)1,061) which are of Triassic age. When the stratigraphic position of thethe Mansa GttdaGuda Formation is considered.considered, the Triassic age suggested by Thompson and Dodson is the most rettSonable.reasonable. As the Mansa Guda Formation doesdoes not crop out in thethe Wajir area.area, thethe readerreader is referred to Thompson and Dodson (up,(op. (iii.cit., p. 15115) for a description of its disposition.disposition, succession and petrography. Although not exposed south of latitude 3‘2° N.N., the existence of the formation under thethe soil cover is proved by a distinct ridge where itsits southerly extension would be expected and by the presence of numerous quartzite pebbles.pebbles, derived from the conglomerates.conglomerates, along channelschannels draining thethe ridge. The pebbles have alsoalso been cemented in aa ferruginous sand of Pleistocene age.age, formingforming a conglomeratic sandstone.sandstone, which Ayers (1952.(1952, maps Nos. 1 andand 212) mapped as outcrops of the MarisaMansa CodaGuda Formation. Since Middle Pleistocene times re—distributionre-distribution of the pebbles derived fromfrom these rocks has been taking place and they are therefore widespread downstream from the presumed position of the Mansa Guda Formation. Immediately east of.of the line Abagaranso—Saturwario-l.ibiduli.Abagaranso-Saturwario-Libiduli, the presence of thethe formation under the soil cert-ercover is alsoalso conconfirmedfirmed by large angular boulders and blocks of quartzite probably deriyedderived from the quartzites in the succession (Thtunpson(Thompson and Dodson.Dodson, up.op. (it.cit., p. 1m.16).

2. DanaDaua Limestone Series The Daua Limestone Series (a term ttscdused by Saggerson and Miller (1957.(1957, '3.p. 10) toto replace the name "Dana"Daua Limestone",Limestone". ﬁfirstrst used by Weir (1929.(1929, pp. 9—11]9-11) to describe the JuraSsicJurassic limestones and shales outcropping in north-eastern Kenya) terminates in an ill-exposedill—exposed broad swing in the Wajir area. It occupies the north-central part of the

t--- --. "''1i: ...... ~ :! - .... ”2‘~ 30' N -“" 'wk-JIR SHEET ' ~i: W~IR SHEET i- :i . JI . . , . . . Ferruginou..and,'on...

. 'l: ' ~ . ~-~9~,oo.~ ' . . . Kh~tK~ot . -.,i:-', . ~ . o;j;, / o~' . . 0<>;.'§ :~~,'.'.' /J :",..."~. . .' . T""-r\ .11 "-r'

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'\ 'AJIR lJt ..==r Abak Fin Akal Ar ~ ~==-~

in .. TJ Orr-3: and biatk gI-lty sells

.1 Red-brown sandy sc-II5 1 PLEISTOCENE(?)0 Red.brown sandy soils (33.3mmGypsum } Wailr Beds 1 limesjnnl‘!Limestone } Wajir Beds EI Reh t, ~ ; I G,", '"' bOd<,eO, ,." _ 2\ MMumurri Limestones Ibrahim *1 lumesmnea} 0Daua LlrrmL ﬂone I Uri JURA, SSIC , au. Imestone . O,d,n,tuDldlrnt-. BodsBeds } Series -'_l - Ssrle$ ~ ~ 1:" 1 ~ 0 S 10 ISM... '8 0 ~ "'O'N, Fig.l-‘ig. l-Sketchl—Sketch map illustratingillustrating thethe distrihulinndistribution of thethe sediments of thethe Wajir-Wajir Bor“or area

- II 1

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TABLE'IABII II StratigraphicalSirilligrupi‘uicd] SucccmionSuccession inin the[he Wajir\‘v’ujir Area I Eras PeriodsI’L‘riods Local representativercprcgcmmiw LithologyLithnlugy EnvironmentIim‘imnmcm of ClimateClimulc Palaeogeographic1’21]:Iungcngruphic depositiondcpmnmn eventscwnlx Recent --- ValleyVulh‘y soilsmils Terrestrial'I'crrcxl rml Dry ----UI} RedRod and brownlmm l1 clays Terrestrial‘I‘m‘u‘sl ['iuI Dry ErosionI‘msiun >. Wet ... i (ircyGrey grittywilly wilxsoils Flood-valleyI lumiwuillvv DepositionDeposit lull os LaminatedLmnimlcd limestonesiimcmmcs LacustrineI.q>lnnc c:I (uncnnﬁu'miU) .,... PleistocenePleistocene I M FerruginousIk‘rruumnus sandstones\;111«I>1011L‘> and TerrestrialICH‘L'MI‘UII Dry <;j I (unconformity) conglomerateconglunm‘alc ::s (I)P\‘l)n‘l PaludalI’ulmlul Wet DepositionHupnhinon

Quaternary Gypsum CY ImpureImpurc limestonesInncuunu‘s LacustrineI Iu‘usll‘nk‘ Wajir\\‘.1jlr BedsHuh I SandstonesStndsmncs Dry LI (?)('3) { Clays(‘luys andumi sandsmum Flood-valleyI IumlwuHx') Wet DepositionI )uposilmn I (unconformity)[unumlhrmitw I 0\‘) Peneplanationl’vm‘nlamuiiun PlioceneI’Iiuccnc ErosionI msmn

MioceneNI inccnc ? 1 Depositionlk‘pcmliun 01!!...

Tcrtiarv OligoceneOliguccnc Extensivel\[un\1\'c continentalunuinunlul (lemonerosion -- Eocene[I we 1 1a: Cretaceous(‘reL'IL-cuus FaultingIllnlling u BurHur Mayo LimestonesI imcMoncx ‘ (ViruyGrey zuuland brownhrmxn limestonesIIIHC‘IIUHL‘w Extensionslcmiun 01'of Ihcthe gulf 10to the northnm’lh 02 [he 0 JurassicJummc Marine\‘IIH'IIIL‘ WarmW :u‘m .,", DidimtuDidimm Beds”CRIN MainlyMainlv fossiliferousI'usxilil‘L-HMx lime-lime, RenewalRe ,u'al nl‘of clown:down- ::EMesozoic (unconformity)(uncunl‘m’mltn stonesstone» warping\x‘n‘pim! MarineMulmr invasioninmxinn TriassicHSSIC (1)I?) .‘V’I unm (huh I ‘ornmt inn Conglomerates( unglmm‘rutm and.1a Deltaicl)cll;uc t(?)2’) AridAmi Down-warping”nun-warping I MansaGuda Formation qquartzitesquill/rim 11

area1171111 211111and disappeazdisappearsfi 1011111115towards the1110 1‘15!east underneath 11a blanket1111111111". 111'of 1’11‘1931111-1‘1‘111Pleistocene 11c1111<11~deposits. ThereThc1‘1‘: arear' 111111101213outcrops but,111111. mmover mm:most 111'of 1111‘the area occupied1‘1‘1‘11131'13'11 1‘1).by the1111‘ .1L11‘118\;;Jurassic 1111125111111“.limestones, resistantrefiistant beds 211-3.are seen 111115.?only :13as strings of 1111111"loose b1111111‘c1'5boulders 21111111;along 1111:the 51111111.strike, scpa1'111c1'1separated by tracts11:11:15 of111' red1211 51131soil with1111111 little111111‘ float.1111111. T1115.This featurefC'11‘111'e is19 distinct(1.1.x11n1‘1 111‘)on the111C :11‘1‘531aerial phatogt‘dphxphotographs and(11111 assisted3353.111:‘11 gz'catl}greatly inE11 mapping1111111131112 :1.1‘Lw'areas 1.111:wheree buckling1‘111‘11'111‘11; of111' the1111: scdfmenisedimentsfi 13111-3gave riser1<1‘ 111to anomalous1111111111111'1118 strikestrikc 11111.1and dip(1111 readingreadings at111 11111111011the widely11. separated90171111111131! 1112‘111'11‘11133.outcrops. AtA1 (1111:1111Gajaja in111 1111‘the north-west,north—11.211. the 11117111511Jurassic limestones1111ICS11111CS dipd1p 202' due11111" east,111.1% 1113the strike1:1'1111‘ gradually15111111t «111':swinging11mg 111to the1111- 1111".east further1'111‘11‘11‘.‘ south“11.11.11 111111and 1"\eventually,c711111111j1. 1‘11‘1'111-L‘L1i1north-east 111'of Riba,R11_1.1 111-:the ~11"11'1‘strike is11 nearnearly (1111‘due aneast with111111 the sediments91:11:111111‘1x‘ 1'1dipping11‘1‘111.‘ to111 the111: 11117111.north. Taking11111111: '111an '111‘1‘111‘1‘average 111pdip 111'of 2r, . '1‘.it can 131‘be 1:2111‘1112111‘11'calculated 111.11that 1111‘the lowest111111.121 4.1111114,000 11.ft. 111'of 111:the Daua131-11111 Limestone1.11111‘~111111‘ .‘111'113Series 1111111occur Inin 111:the \\'-.1_111'Wajir 111‘11‘3area. '11‘111‘The 11114-1:base of 11111"the Daua13111111 Limestone1 11‘1cq21‘125: S1111):Series 1m».was 1111:not 11111011111observed 111in 2111-1the ‘1\Wajir'11" area, but further1111111121 north11111111 Thompson1111'11'11px111'1 11'1111and DodsonDndml‘. 11“1’111‘.(1960, p.11. 2111‘;20) found10111111 111‘the .1Jurassic1 111111111: 11:sediments1131113 mer—over- lapping 1111‘the 311111311Mansa (11111.1Guda 1'11111‘111111111Formation. Because”1111:1‘ 111'of 1111‘the 1‘11111'1'11paucity 111'of 1‘exposure,1111‘11111‘. 1111‘1‘1‘there :11is 1111no {3111111proof 111‘11111111around \\Wajir11151‘ 111'of 11a 11.13511;break 511in 1111"the 501111111‘11111'1'1"11sedimentation 1511‘:of the DauaD111? 1'Limestone11111'»”1111‘ 531‘:Series,ea. 131:1but 1111111111111;according 11.1to 171111191111Thompson 111111and DodsonD1111m11 111.111.(op. 11.11..dr., 11.p. 2111‘20) 1'11:the 11'seriesu 11111can 11-11be 1111111111:divided into.1111 11.111two pansparts 1111on 2111011111account 111'of 1-1a 1111:1111321‘11postulated 1111‘1‘11111overlap 111'of bcdx‘beds 111'!of Bathonian-Callovian311111111111 .m--C"11. 1111.11.11 111.11:age 1.111111onto 1111‘the 131111111111Didimtu B1111

1111')(a) 1310111111DIDIMTUBEDS81:13.11 The'J'hc \C1111ct11‘1‘sequence 111in 3111‘the Didimtu131115111111 Beds13121 111111can 11.1111only 111‘be 111‘determined1‘111111‘111 from1'1‘11111 11111191111111occasional 11111111111cobbles 1111on 1h1‘the surface in thcthe 111111'1‘1'lower partpan". 111111and 110111from 11.1narrow[111.11 11111121111215.outcrops 111‘or flflagsags 111in 1111‘the upper part,11:111. >111so 111111that 1111no thickncwcsthicknesses 111'of 1111:the 13111111.»;various 1110111111211:members 11111111could be c1c1e1‘111111cd.determined, though 11it umcan 1.11-be CL-‘111rL11calculated111011 {1111‘that 1111‘the 111‘111beds 1.15as :1a whole1111111: 111111111attain '11a 1h11‘kthicknessflc‘fifi' 111'of 120121) 1'1.ft. in111 the arm.area. 111::The most1111111 1111111111‘11‘complete wqucsequence1"'.‘ 11115was 1'11‘1111'1‘11‘11obtained 311.111.1113.halfway between1101111‘11'11 C111_"1j11Gajaja 3:111and Forogorgor11111111071401 \1/.‘viz.:- ('1.6. Thin 11mmbrown 111to gm}grey 1'1.1\~1111'1‘1‘1111.~fossiliferous 10to 11111111110111coquinoid limestones1‘11‘111‘1111111‘5 5. (1111111131Cobbles of111' dense111‘1‘1\'1‘ gm}grey .11‘g111111‘1‘11'11aargillaceous limestone111‘. 11‘<111:11‘ with11.1111 yellow_11‘1111-.1 111111111113mottling 4. FlagsFlu-:14 111'of :11‘11111115511yellowish 111‘111'11'1brown {01911111711111fossiliferous 11111181011113limestones 3. DenseDunne grc‘}grey 11rg111111‘1‘11115argillaceous 1111111‘510111‘limestone cabbimcobbles \11'11‘1with 1‘1‘1’1red mottling;1111111111114: 11111241111131occasional hard1121111 grey 01'or 111111111brown 1'1111‘111‘finely recrystallized1'1‘1‘1'j.\11111171‘1'1 111111‘1‘11111‘.‘limestone 11111111138cobbles _.2. 5111:1111Small 1:1.‘111‘11‘9cobbles 111'of 1yellow-brownc111m— 111111111 111111111"oolitic '11111‘1‘11'111-1"limestone 1111111with 1111‘g1‘1‘larger 1.1.‘1‘1.grey 111111111‘11mottled argillaceous11115111111115 11:11:31.11‘11‘limestone 1‘1‘1‘11111‘1'cobbles 1.I. Boulders1301111111“ (”11'of 111‘1151‘dense brmu11<11brownish g'x‘}grey :11;111111c1'111\argillaceous limestones'.111‘~1.1111;'< 111111with few1:11 1'1‘1w11fossil frag-11.15;!- :111‘1115ments 111‘11and _\1‘1111‘11.yellow 11111111:mottling111:1 Specimen51131‘1'1111‘11 31/131 1'1"* from1'1‘11111 the1111‘ £1[2'1 WakV1111. 1‘112'111road isEM 1111an example“111111111-‘111of 1:11‘the 1:11:11basal 1111121111member. of the Didimtu131111111111 BedsBC1‘1'11'11'and 11111151515consists 111'of 11a 11111111;finely 11.111111111131311recrystallized gm}.grey 1111111211.matrix $111101enclosing‘ 11111111311111numerous

1111111111:minute grey 111‘11-1‘15pellets 1111.11and 0.a few13:11.1 P111"larger,[- . partly;‘.11"11j. 1'1‘1'1'152'111'11'11‘11recrystallized 15111111111111»,argillaceous pellets.11“.» In171 thin1111. 13:111111section 11111this fragmental1"‘11g11‘1-1‘1‘1‘11‘11 11111131111111limestone is1\ ~1‘1-‘11seen 111to .1111‘11111consist 111'of 11111111‘1‘0111numerous i111:shell fragmentsg1t1c111a‘ and 111111'1‘some rounded111111111611 111111

- I --~------'1

} t

TABLE 11II

The Correlation of thethe Jurassic LimestonesLimestoncs of north-eastern Kenya -- ! Stages of01‘ the EntireFrltirc Area Mandera-Mandcra— I Derkali-MelkaDcrluili -Mc|ka ; Takabba-Takabhu-— El Wak-AusWalk—Ans; i Burllur Mayo-Mayo— Present Reportcnrl Jurassic (Ayers, 1952)I‘J52) ' Damassa[)umflssa area I MurriMurrl area . Wergudud area MandulaMundula area : TarbajTurbaj areaurea (Joubert,(Jouberl, 1960)”‘60) (Thompson('l'hnmpson and I (Saggerson(Suggemun and (Baker and I (Thompson and _ I Dodson,Dodson. 1958)1958'} 'Miller,' Miller. 1957)195?) Saggerson,Saggcrson, 1958) | Dodson, 1960)I‘Jfifl) 5 Tithonian'Tithmliun ManderaMunderu SeriesSeries; ManderaMundcra Series I ' ...._.__.._ ..._.__..__ .___...._--.. ..._._.______.. M : (Not(Nor . (Not Upper I DakachaDel-rachal exposed) exposed) KimmeridgianKimmct'idgluu 5 ----LimestonesLimestoncs LimestonesL1mesmnes : I I I Upper ShalesShalcs HereriI-lcrct'i shalesshulcs I .' : ' -- | ‘ , _ . 2"'" Middle I Seir Limestones I g "Upper"“Upper“ Daua ' "Oxfordian""()xtordmn“ (Not I (Not[Nut 00 0) -~ 'C6 LimestonesLimestoncs ! Limestones[..imestones g Limestoneslcslnnes exposed)cxpescd) exposed)exposed] 0) .. .. . _.._....-.. _..,_...... _ tfJU ...... OxfordianOxfordlun ‘30) . : GolberobeUolbcrobc Bedsnods Golberobe(.iolberobe BedsBed !::r: ,3---- - =__—#.. .. ____.___.__..__. .. I: I .9a'" i Middle Shales I RahmuRalmlu ShalesShades I :u i""'----...... _.._._...... _., ...... _...... _..._ ...... _| I .E8 ' Muddo Erril-ei I ;:J'-I Lower LimestonesLimesloncs 1 "Lower"“Lower" MainMarin _ -_ - -- - ." .. osg LimestonesLimestoncs _ DauaDuua Oolite()nlitc I Callovian(.‘ullm-mn g1; i RukesaRukesu ShalesShules AsaharbitoAsuharbno Beds LimestonesLimesiloncs LimestonesLilncsloncs . . ._ 0-— _ I __ ...__.______g i BurBI” Mayo Burliur Mayo Bathonianllgtthonjun I ; I Murri Murri _ ' j LimestonesLunesrones LimestonesLimesmnci BajocianBujucian i I I LimestonesLimestuncs LimestonesLirncstoncs i Marl HorizonHUrizdn - .. .. .- ...... l '------n - . - ' -- '_—"__—.———__- (Not exposed)expuggd} I [Not expoggd'} I I LiasHas ' DidimtuDiclimm Beds (Not exposed) : (Not exposed)expuscd) I i Didimtu Beds f Didimtu BedsBeds; i I (Not exposed) ~ ~i

Specimen 31/38,H.538. a banded dolomiticdolonti ic limestoneliitiestone collected at Forogorgor,liorogorgor. occurs slightly higher inin thethe Didimtu[)idimtu Beds succession andand consists of dark grey,grey finelyfinely re-re— crystallizedcrystallixcd limestone with irregular dense red material,material. the latterlatter also occurring as thin lineslines and small spots. Under the microscope the clear recrystallizedrecrystallized matrix is seen to contain numerous elongated dense tubular or ovoid bodies,bodies. shell fragments in a somewhat linear arrangement,arrangement. and some ooliths. The ooliths,oolEths. generally perfectly round and about 0.3 mm. across,across. show concentric and radial structures and enclose cores of calcite crystals, ferruginous material and commonly organic remains.remains. Thethe radial structures have formed at the expense of concentricity in the ooliths as a result of alteration. Dense red irregular patches occur in partsparts ofof the section and are seen to consist of small globules of hematite scattereds‘attered throughout a fineline carbonate matrix,matrix. while in some parts,parts. hematite and limonite are so abundant as to exclude all carbonate. Wherever fossilfossn fragments occur within the ferruginous patches,patches. they are separated from the iron oxides by clear crystalline carbonate rims. Dolomite is seen as aggregates of euhedra replacing the calcite,calcite. while secondary quartzquartz. is encountered in the dense rounded pellets. Thin‘I'hirt cracks filledfilled with clear calcite traversetrayersc the thin section. The upper part of the Didimtu Beds is best exposed in the CiajajaGajaja area where thin flaggytlaggy pavements of yellow-brown fossiliferousflassilit'erous and dark grey coquinoidcuinoid limestones alternate with bands in which occasional dense mottled argillaceousargillaeeous limestone cobbles are encountered. The lowest horizon of the fossiliferousl‘ossililerous limestones (specimen 3131"?)/7) is a fawn-colouredfawn—coloured yellow-weathering,yellow—weathering. finelyFinely recrystallized limestone. Normally such a rock would be massive,massive. but because of the thinness of the bedding andanti resistance to erosion,erosion. it occurs as a series of flags strung out along the strike. Black shell fragments are all arranged parallel to the bedding. In thin section numerous ooliths,ooliths. and very often elongated lenticular fossil fragmentsfragments in linear arrangement,arrangement. occur scattered throughout an even—grainedeven-grained mosaicmOsaic of yellow-stainedyellow—stained calcitecalcite. Where the matrix is clear.clear, small globules ofof. limonite occur interstitially. The ooliths have sometimes formed around single crystals of calcite,calcite. 'butbut mainly around pellets composed of finelyfinely divided calcareous matter. Composite ooliths are rare,rare. while occasional foraminiferalloraminiferal tests are encountered in the matrix or enclosed by oolith rims. The fossil content of the Didimtu Beds at GajajaCiajaja sometimes increases to such an extent that the limestones become coquinoid with the black shell fragments, all roughly arranged parallel to the bedding,bedding. imbeddedimbcdded in a yellowish brown calcareous matrix and impartingimparting a general dark grey colour to the rock. Under the microscope specimen 31/831,-"8 from Gajaja is seen to consist of an equigranular iron-stainediron—stained calcite mosaic containing many shell fragments. The iron-staining is usually most prominent around shell frag-frag— ments and is of a patchy nature. Occasional large clear patches ot‘of interlocking anhedra of calcite have formed in the spaces between the shells.shells, the shell fragments being them—them- selves sometimes recrystallized.recrystallized. The shell fragments are often rimmed by dense black material,material. probably manganiferous,manganiferons, which imparts the black colour to the shells in hand-hand— specimen.spccimen. Limonite[.intonite globules occur scattered throughout the matrix or as small aggre-aggre— gates, while occasional angular detrital quartz grains occuroceur within the calcite matrix. Fossils occur in profusion in some of the limestones of the Didimtu Beds in the Wajir area,area. but no fossilsfos ils suitable for identificationidentification were collected as they resist removal without fracture frontfrom the enclosing rock. There is,is. however,however. no doubt as to the age of these beds as a significantsignificant fauna has been yielded by the argillaceousargillaeeous beds at Didimtu and north-eastnorth—east of Tarbaj'l‘arbaj hill, north of the present area (Ayers,(Ayers. 1952,1952. pp. 9 and 26-27;Eta-2?: Thompson and Dodson,Dodson. 1960,1960. pp. 22-24).22—24}. The fossils of consequence are PectenPct-rm (Weyla)[lir'eylol ombongoensisambongoensis Thevenin,Theyenin. a species described from the Upper Lias of Madagascar; a spiriferina like S.5. rostratarostrutrt var. madagascarensis,inon’ogrtscarcnsir. a genus which became extinct in the Lias;Lias: Bou/icerasBonita-eras nitescensititesccns Thevenin,Tl’lcyenin. which is characteristic of the Toarcian;"l"oarcian: and ParacenocerasParocenocerrts anomphalumanomphrtlmrt (pia),(Pia). mainly a Toarcian species. The fossils not only establish the age of the Didimtu Beds but also indicate a marine link with the Kenya coast and Madagascar during those times,times. a link that was severed during the mid-mid— UpperL'pper Jurassic period.

I . .-.

101|”)

if)";(b) BUR MamMAYOLIMESTONES1.i.\ii,-'iu\1.s

Inln a:1 discussiondFScLJSsEUH unon theihc iiage ofiii the[Eic Bur Mayo Limestones,l.l[T'lC\iUi1L‘\. 'lThompsonhnmpmri and DodsonDuos-w (1960,([960. p. 33]33) mentionmcmiun that1‘14: the Aalenian»\;1[::1iiii‘. iii‘i‘.and BajocianBuﬁngiiii‘. Ll‘i‘i‘rL‘lll’appear :uto hr:be missingi]1l\\i11LI mas nor... fossilsl'iiSSils indicatingindicaliﬁg Il‘it‘xcthese sing-cwstages havehm: beenhelm found,loulul. and thatH131 the:l'ic limestoneslimusluucx can beb: lilL'xi-dated as Bathonian-Callovian.Batheniun—Cullmiun.

The sequcngrsequence inii‘i ll“:the Bur”LIT Mayo“2.30. Limestonesl.lI‘IlC\iUJ‘u"\ umwas dcturminciidetermined largely» froml’i'Ui' bouldersimiaiiiiq‘ Lilimgalong the strikes u!‘of :hcthe \‘Lii'iniisvarious resixiunlresistant hm'i/i‘l.horizons, which flarel'L‘ sci-Linn“?separated by trucktracts 41'of milsoil unitainingcontaining fifloatnal \of [hL‘the undcrunderlying'3'n \ulimcnlk'.sediments. UuicmpqOutcrops do ngcui'occur in lhuthe (mjajiiGajaja men.area, which gave mostman 05'of the1h: (widen-grevidence fori‘L'i. thelhc xiihdixixionsubdivision L‘i‘of 1h:the lowerlimcl‘ partpurl of iiicthe successionxLJ-qcm-iini‘ and in theahe north-centralnorth—u: I'ul partspurzx \ihcrcwhere 1h:the niidLiI-cmiddle \L-qirsnx:sequence of thelh: \lJC;CS'~l0Hsuccession was\\L1\ uiwluincil.obtained. Furtherl‘ui‘thCI eastE1151 no outcropsfililL‘l‘UDS were“CI": encounteredL‘DQULJH'LCTCLI so‘~I.l thatiliii‘. onlynnl} scanty\‘211113 information;‘1J‘.n‘:11;i[|.‘|‘. existstwin i'l‘on the1h: upper BurBier MayoMagi! Limestones.l,l[]:L'\1UE‘I:.'\.

'lhi‘The \ciiucm-usequence axas ill.1;"|“.‘Limapped '\is izxas llillms-w:follows:- Approximate,1 p;H'rJJ‘i'nry-‘i' i'l'ii'rx'iuruthickness feet."['(‘.'I 8.S. Mainly brown to buffbut? ooliticOUlIElL‘ and grey1121‘} argillaceous:n‘giil‘uwim limestones.llll‘iCNIi‘-]15\ . . .i . ],750LTSU 7.T. Mainly non-ooliticnon—Golitic brownbrmm bandedbizliilt’ii and Limitdense 131‘}grey lll‘;‘lC>lO|}C\limestones , . 901]900 6.f). Oolitic()Olitic brown and greygi'e} bandedhdl‘ltiL'Ll limestones.lil‘s‘lrnii‘nL's'. . ._ . ,. - , 140I-Stl 5.5‘ Non-ooliticNan-Golitic brownbmwn bandedbaimlcd and greygm} argillaceousLlrglilJCCilzlx limestoneslilTIL’S'.UDC\ 470‘ 4. Thin-beddedTl‘iin-bcddcd hardhiil‘d finelyﬁrmly recrystallizedi‘ucr} sliiliizud or dLnxL‘dense brownishhl'i\\\:1i~h grcxgrey limestones,l!|1‘.L‘\lUHC\_ sometimessomctimes banded.banded . . A...... - ' . . 110l H] 3. Thin brown flagsﬂags and occasional gi‘qgrey i1argillaceousrgilluccoim limcsiimclimestone (Uhhlcxcobbles . 17017:1! 2. Thin brownbroun bandedhanded and densedcnsc greygit} argillaceousill'glllLiCL‘ULh linicsmnolimestones _. . . i 110l [U 1. Dense grey iil‘gilliiccumargillaceous limestoneslimcxiunux with prominentpmmincn': yellowIxcilim anditml redml mottling , i , . . , . . . 1601m

Total.'Iuhil . . _ 3,810Sﬁil}

TheThis hawbase ofml the[ll-c Bur Mayo31:13” LimestonesI l‘.1‘.:\ld|1L‘\ (1)[II Ris bestbut exposedcums-{ii along:a'img the1hr hillh.E| front[rum at..i Gajaja(jujaja and consistscusixixts ofnj' densedfljv; greygr; argillaceous;;i'gili';:;cn;1~ limestonesliq‘cfilolir\ (calciteicaluitc mudstones)INLIlfLmCsl with\xiih dis-div tinctiveiinctixe red and yellow)L’lln“ mottling.nmiilfng, Within\Kiihin the \zis'nuistained patches,1 zighufi. 1h:the limestoneslimhhincx \sometimesfllHL‘lii‘l‘lLN containumtain clear acicularauiuiilm' crystals{rpm}; andarid onlymil} rarely,I'LH‘CI). solution\oiiriiun cavities.L'miiFL-s: SouthSdilll‘l of Gajaja(iajzijii theseilk-w limestonesSim-cumin formfm‘m the:lic ulgcedge oful' thelhc higherhigh-cl: kgroundvim-J built ofnl' theilic JurassicJurawic sediments,x-cdim-cnts. but111;: thefilm reliefi'clicf is much less1cm prominentl ‘1\ herehi": than111.1:1 atLii Gajaja(jifiJjJ. hilL OaxOccasionallyfimull} Cngl:single fossils'{nxxilx :1-are ".'.I'.\ found imbeddedimbcddcd in theilic argiJIaceousERUK'UEW limestones,‘i ‘ ‘ but two:xm min-Tsofter unexposedmun-mil horizonsFinriz‘am forming groovesgmmux onL'!! the[ll-c hilllli.l front1.'u‘|‘= maymug. be1m; fossiliferous.In“! 'L mm. TheseI'm-xi- beds,hcilx. cmcruicovered byh}: talus111i |\ and.md notnut L‘XpiWCdexposed l’Lzrthc‘.‘further south,wmh. divideLli\‘i.|c lhcthe l‘llbasalfiJl hubbeds :11at (iniuiuGajaja Emuinto Ilii‘c-cthree thick-beddediiiicli-b; bands.1*.21 11 Lb. Inln thin section\cclinn specimenRITL‘Clil‘iLJH 31/6'~ I h froml'mm (rm-l"Gajaja, \‘Iiicone At»of thcthe CLiEL'i'iCcalcite mudxtum-w.mudstones, is sci-:1seen to10 consistcunsiq of finelyfinch.- djvidcddivided calcareousL'LilL'Lil‘L‘L'IUH matter,2 nil-c1: il\"l\L‘i}densely \II‘L‘HI‘Istrewn with\ailli small globulesglnlmilm of”5' limonite"' limiiu which sometimessunictimcx aggregatemm ‘ to form dark' brownhl‘u'ikn patches.Wat-chm. OccasionalUgcuxinl‘ smail' !‘ -.- -'x ‘ “.p-\'\..7.,‘,i.r, clearJar pushespatches of finelyfinely recrystallizedrut; calcite occur and“L: MI.where Innthese Lu;are .L1.:L‘..j.:lenticular Link.and -.‘I.n'\:d.curved, Ila-:1.they (11':are thoughtihnug. to10 replace:3“ shell fragments. MinuteM111=Itc :ingii..irangular 31:1!"lgrains allof tll'U‘iudetrital \iLlLif'E/quartz gm:are Scatteredscattered thinly butIviz! can}evenly throughout the matrix.milll'fx. TheThu succeeding~.'L!.'CCCLi-: limestones (2) consist of thin yellowish brown beds alternating with grey argillaceousurgillaccnus limestones with yellow mottling, fossiliferous in the lower part and laminated“in: inIn theIla-e higher.Eighcr. The first-mentioned rock type is prominent in the lower parts. where numerous flagsflag» and slabs of red-weathering limestones occur strewn on the surface. while occasional' 'ctmi cobbles of grey argillaceous limestone indicate that this type

[~ !!!!I!!!!! ==_. - 11J l

formsI'or2'115 a minor component of the sequence.51115111311111. Higher in the succession the mottled argillaceousru1l1111ou5 limestones become prot11i1'11nt11'1thprominent, with a darken't‘zudarkening in the colourColour ofol' the tit"tthin bandedh'.tt1d-..d limelimestonesstones from yellowvellow to red to oath”dark purplishpLIrnltsh grey.211:1. The sequence is term-i—termi- nated by a g1c1=i5hgreyish brown{31111111 fifinelynch bandedhand:12 limestone.l'. n1e5tone. The lowest bed is15 11111111115111:distinctive in being bandedhanded in511. red,red. brown and are}.grey, and recrystallized along bands. Specimen 31/37,31’37. collected east ot'of Forogorgor,Fot‘ogorgot‘ has1121.5 a roughtrough finelyfinely pitted surface,surface. which rereflectsflects 1111:the ooilticoolitic nature of the rock. 'lThe211‘ freshlyT"1.5.11l't'.'-1cttir1:1lfractured 5'11ri;1cesurface is grey with large irregularIrregular yell-311yellow and red patches and 11111111513115numerous small dart.dark 5t1‘ucture5essstructureless 5pherule5.spherules. inIn ththintan section :.tit i.5is rewaledrevealed 1'15as ntict'o—codttinoi'tlmicro-coquinoid withnitl‘t nu111et'ot15numerous fossil1115511 fragments.fragments, foraminit'era.foraminifera, ct‘inoidcrinoid 115'.i1':lcsossicles and clay pcllet5'.pellets, neat'l}nearly 3-“all “i131with 3“an oolithic rim.rim, emplaced in '11a fifinelynely t'cct'recrystallizedallized calcite matrix. Brown ferruginous'ez'I'LIgin-ntts patches111111115 are seen.seen, with higher magnilication.magnification, to consi5‘1consist 11:of 11113511:1"5mosaics 11'1”of 111.1l1‘.-1‘.tt'-dolomite-e eLzhcoeuhedra with Interstitialinterstitial and intergrown globules of lintonite.limonite. 'iThehe claclay pelletspellets oreare usually 111.-dense,.. but sometimes have rect‘1'5tallézedrecrystallized cores.cores, and 1111111111511normally contain 11a fewl'ew elasticclastic grains 11t'of 1111:1117.quartz. In the hand—specimenhand-specimen 31.55.31/5, collected in the (3:11:01:Gajaja 11113.1.area, is LI.a 111:1151‘dense gt'egreyish31.5h brown limestone joined at 11a sharp contact \13thwith '.1a red recrystallized liI1e5to1t:limestone with numerous red spherttles.spherules. Under the microscope 3i31/5.‘- resembles 3i31/37,3?. ‘11-.11.but iti: is 11111—bio- clastieclastic with advanced recrystallization of the dolomitic coicltecalcite 1matrix,1.1‘1 5. and with 1113“}many 111'of the rounded detritaidetrital pellets containing '.-.a Cat'gclarge 111111111111amount oi'of iimonatelimonite globules. Slightly higherhizhcr in the succession511ece55ion ata: (Edi-11in.Gajaja, specimen 31/1033: '51} was cube-credcollected. It is a red-weathering,ted—11. eathering. tiaggy.flaggy, yellow,yellow. rect}'s1.recrystallizedzed limestonel1111c5‘t1.‘.t1e :-1I1dand occurs within'1'1".tl‘.-1I‘1 the fossilifer- 11115ous zone as it contains numerous shellshell lt'aumcnts.fragments, nartlypartly de5tI'destroyed1_\'1‘d h_\.'by 1"“'recrystallization." 'l'heThe thin section is ”thatthat of a coquinoitl1'.-'1'.'11-tI.1‘n:'tccoquinoid calcarenite 1‘t‘llitliiiliifcontaining large and small shell fragments,fragments. numerous dense pelletspellet.5 avet‘aaveraging 0.15l5 111111.mm. 11::1'115'5.across, I:-I'1tb11bi_1_.'probably 115'of t"faecal- origin. and partly destroyed OOlEthsooliths asas well 1as 01.occasionalca5i1‘1nnl CI'Enoidcrinoid o55ic|c5ossicles in a recrystallized calcite matrix. All these dense pellets tend to become part"partly '.1l15111'hc11absorbed l1}:by the recrystal- iixedlized matrix.matrix, which also contains some d1':I‘i'1'.Ildetrital 1111111111.quartz gt'un.grains.. 'l'heThe succeeding beds (31}(3) 111rof the Bur1’.-11F M11111Mayo Limestonesl.iI'.11-5‘.-.11':e5 are distinguished by their lack ofexpo5u1'cof exposure and it isi5t155umedassumed that they consi5tconsist mainly1111111113 oiof "argillaceous rocks. Thin brown laminated flflagsag5' outcrop.outcrop, however.however, and their silty natot':nature E5is reflected by_' tinefine .'1-1155'cross- bedding on weathered surfaces. The 5:.!siltstonestones are presumedt1."1‘5't.-'11‘.c1i to at:alternateI‘natc with brownishownish .gt‘e):grey dense urgill'argillaceous,ceous. banded and DUI'L‘CHJHIHHporcellanous iir11e5'111nc5limestones which 1.‘occasionally appear '115as cobblescobbles 1111on the surface. The beds t'orntform 1.1a hollow alongalong :11'the 511'3'5:strike between two ridges .='..I='formed1‘.-11:11‘ by the 1e51'5t-1111tresistant liItIesL-onelimestone beds below and ohm-1.1above 1t1cn‘.them. Inin contrast to the underlying beds,i1-1'u'5'. the1'11; rocksI'111'l15 11"of group“1111p [—11(4) c11I15:5:.consist 11:of hard re- 1"1'3'5'tallizedcrystallized grevgrey limestones,li1n1.5tone5. which form a11 1'LII'1'cdcurved ridgeI'E'dge along the strike.I5:‘-.I'i'11c. Specimen 31/28,3E 28. collected near thethettop of11-1"this sequence, five miles5: 5.1'._Itft—1‘t15tsouth-east of {1'Gajaja, is a dense ':.11'1'1'-.1'I1i5hbrownish E'grey".V' limestone' with occasional patches of recrystallized1'131‘1'15'1'ctiiixc'1i 1'calcite. and faint banding.binding. In thin section numerous dense pellets, usually 0.2 mm. 1-11‘1'1'155across but which may"1‘.-11y be 3'5as largelai'ge a5as ().—‘10.4 mm.111111. occur in profusion111111.15” in a matrix that is only slightly less 121111.51:dense than the pellets. Many dett‘iteldetrital grainstins 111'or aggregates of calcite crystals, usually rounded and iron-stained.iron-stained, .'11'eare clearer'c at'ct' than the matrix and are enclosed by rims of dodensese calcareous matter.matter, and it isi5 [noughtthought titthat.11 ‘1tthey may have arisen by recrystallization -.1i'of the.be dense pellets. Angular\ngula: o‘cmtzquartz _.grains' are commonly found in the dense pellets, '.1:‘11'land ovoid pellets :11:are at'ttrarranged1115111”: withwi1h theirI. longer axes parallel to the bedding. The pseudo-oolitic1151:11d11—1111Ei..c nature of this rock is 111'of 11I".1~1‘primary sedimentary origin as vague sorting of "—-1. the.I'c. pelletsoellct5 i5is noticeable. The lo‘1'1c1'lower pett‘tpart oiof the succeeding beds {3'1(5) 1'5is 111again poorly exposed,1111111] dorkdark dens.-dense argillaceous'5aee1t-111; limestone cobbles indicatineindicating that[httt 1?1i5this type forms=' thetl“--‘ major1_:':' part1. :'t 111'of the 5'-sequence..11111121'e. In 1111:the better exposedexposed higher par:part browbrown colours become 1“moreOH} 11b:.1111i'_I1'1:abundant

I".1in 1'e5.resistant51.1111 i1.11':'/1':I15.horizons, 1le1'151dense r1)1l<"b'.rocks being(“:I brownish grey with some thin finely recrystal-rccr_5.5t'.1| lized'Cl bibrown'L"\\t‘| limestonelittlest 1e horizons. Near the top yellowish brown recrystallized, sometimes "..11d.-'.‘1l.banded, iir'11115t11n-1.limestones and bullbuff porcella nous limestones break the monotony of the

. r

121'1

succession,succession. the upper limit of the beds being markedmarl-Led byb} thin poorlypoorl} fossiliferoust‘ossilit'erOLh horizons,horizons. sometimes somewhat oolitic,oolitic. whichvxhich form the base of the "'Overlyingoveriving oolitic rocks. Rocks of oolitic nature are common in the Bur Mayo Limestones,Litttestones. but nolitesoolites are especially abundant in the uppertime: partnot (6),let. forming a zone approximately 140Hit ft.it. thick and about]about 1.000,000 ft. above the base of the formation,formation. The lowest bed 'Ofof this Zonezone is unmistakable as it includes large chert nodulesnodulex containing numerous.numerous ooliths.ooliths, elongated and strung out along1along the bedding.bedding, and forming prominent vvhitishwhitish protruding knobs on finelytinelv pitted red weathered\veathered surfaces. OftenOl'ten smiLllsmall shell fragments,fragments. all arranged parallel to the bedding,bedding. occuroceur in bands in this horizonhorizon. In[:1 thin section.section, specimen 3t31/11“ll from 292'1) miles north-eastnorth—east of Wajir\\ aiir on the EIEl Wak“lulx road,road is found to contain numerous ferruginoust'crruginous ooliths,ooiithx. partly altered to dense strstructurelessiu tutelex's pellets,pelletx‘. and averaging 0.6 mm.mm across,across. in L:a finelyfinely: divided carbonate matrix. InIn the matrixmatrts lenticularlcntieular shell fragmentsiiagments contcomposed1<1sed olof largeiLLLrge clear calcite unheetanhedra or partly or entirely replaced by;by L‘h'LtlceL'lonLLchalcedonic silica indicate vague bedding. Occasional oolithx‘ooliths are ovoid.ovoid, but the majority are perfectly round while\\ hue composite ooliths are rare. C‘hslcedonvChalcedony also forms patches in the matrix,matrix. showing tinefine aggregate x'tttstructuretcttue underL; :1l crL1x1

r - o-=r-~ ~ !!!I!!I:"" ~. I

south of the El WakWalt road large and small irregularirregular angular dense argillaceoasargillaceous blobs and pellets occur within recrystallized limestones. As this type of "brecciated"“brecciated” limestone isis: not confinedconﬁned to the oolitic zone and is not constant along the strike,strike. itit is probable that later deformation,deformation. possibly as a result of faulting,faulting. caused partial recrystallization,recrystallization. leav- ing angular blocksblocks: and blobs of the original rock ﬂfloatingoating in the finely recrystallized parts. Towards the south along the strike of thisthis” zone,zone. oolitesoolltcs become less prominent buthit their appearance interbedded withuith grey and bt'oyynbrown limestones still serves to separate the zone as a distinctivedistinctiyc unit.

OverlyingOyerlying the oolitic zone are limestoneslimestonCs (7)<71 of the santcsame typestypes” as those described above but,but. because oolitesoolitcs are not so obvious as before,before. the beds serveserye to separate the oolitic zonemm from the upper part ofoi the Bur Mayo Limestones wherexi. here ooliths are common in nearly all the outcrops and groups of boulders. Most limestones of thisth‘s part of the sequence are dense and argillaceousargfllaccotis and.and, under the microscope,microsct'ipc. are seen to consist of finely divided carbonate with minor detrital quartz. Specimen 31/15,31 ‘15. collected '3030 miles from Wajir on the El WakWat-\- road,road. is a yellowishyeliowish brownbroon porcellanous limestone whichwhici under the microscope,microscope. displays numerous indistinct dense pellets in a finelylineiy divided carbonate matrix. The pellets average 0.1(1.1 mm. across and areare. often iron-stained,iron—stained. in whichWhich case they are more distinct. Inin specimen 31/1631 lii from the samesame. locality,locality. a dark grey limestone,limestone. the pellets are much larger and although they vary in size,size. are generally 0.4[1.4 to 0.5ti._< mm. across. Perfectly round pellets are scarce and often showshou a vagueyague eon-concentric structure. The pellets are closely packed in parts of the thin section and tend to shape to the availableayailablc space and therefore must havetime been relativelyrclatiyely plastic to yield to pressure during compaction.ct'itnpaction. Inin contrast to specimen 31/15,31 15. the matrix here consists of clear anhedral crystals of calcite. Specimen 31/ 17,17. an example of the fewten oolites that occur in these beds,beds. was“as aJsoalso collected on the El1-11 WakWalt road,road. 31 miles from Wajir.\\ .1jll'. Itit is a perfect example of a rock derived by the erosion and redeposition of an already deposited calcareous layer. The weathered surface is.is banded by thin inconsistent resistant lines displaying current bedding and reflectingreﬂecting the silty nature of some of the bedding planes. Under the micro-micro— scope numerous ooliths.ooliths, pellets and allogenicl-illtlgtl‘l'tlc grains are seen,seen. enclosed by an equigranular recrystallized dolomitic matrix.matrix, withnith the angular elasticclastic grains of quartz and plagioclaseplagioelase more concentrated in zones parallel to the bedding. Pellets and ooliths are usually elongated parallel to the bedding planes,planes. but are evenly distributed. Allogenic calcite clusters.clusters, usually iron-stained.iron-stained, as well as some of the elasticclastic grains collected a dense calcareous rim in the process of transportation before final deposition. Dense pellets are sometimes enclosed by concentric oolithic rims which havehaye often been broken in the process of deposition and recrystallization of the groundmass. Leaf-shapedLeaf—shaped pellets,pellets. arranged with longer axes parallel to the bedding planes,planes. are thought to have been deriyedderived by the rolling of the pellets in one plane only,only. and point to strong and consistent currents in one direction. Occasional small angular fragments of large shells in the matrix also point to powerful currents,currents. A few foraminifera are present. Fossiliferous zones are nearly always found associated with the oolites and it is therefore consistent that a fessfew fossiliferous hori/onshorizons ha\ehave been found inin thesethese beds. Specimen 31 /‘1818 is an emmpleexample of such a rock.rock, consisting of shell fragments,fragments. arranged roughly parallel to the bedding planes,planes. many dense pellets and a tenfew poorly preservedpreserxed ooliths in a coarsely re‘rystalli/edrecrystallized clear calcite matrixmatrix.

Specimenr~Specimen 31/19,31 1‘), collected 31R1 miles from Wajir\N‘ajir on the El WakWalt road,road. is a clasticelastic limestone consisting of small lenticularlcnticular dense grains in 21a fineline eqtligranulzlrequigranular grotmdmassgroundmass. Occasional larger round dense pellets occur but are indistinct,indistinct. as by recrystallizationrecrystalli/atfon they have coniccome almost to resemble the groundmass. ‘lheThe lenticular pellets are all arranged parallel to the bedding planes,piancs, and a \aguevague sorting is noticeable ini: the thin:hin

~ . -

H14

section,icL'Lfnn. while‘.1'111lL1 in the hand-specimenl1;111Ll-:13L'L'i111L1:1 banding isi\ seen\E‘Un as'LLs finelinL' currentcin‘rL'n'L bedding. A fewfun quartzLI'LiarIz grainsgi'uim and small shell\h'cll fragments1131;111:2115 completeL‘L1111piL‘lc thei'nL" compositionLL1111pL1\i1.iL'1n of this rock.1'L1L'iL'. Speci- men 31/20,3i :11 11a calcareniteilL‘areniic fromfrom theIhr‘: same

An.\n intra-formationali:111"LL-l'L11'n'1atiL1n'L-il LL111glL1111L'1‘L'i'LL'conglomerate HpL-L'in‘L-L'n(specimen 3‘.31/59)371)) wasnew 1'L1‘Ll11Llfound ‘Li11'-threeL213 miles111i} cs 110tsouth-h- west'-.\L‘\[ of ShanderinotShandermot where a 1i11c—L11'.1i-1L1Lifine-grained greyL119; limestonelim'tnnL Lu.within 1111111L1L1Lh'numerous small red1'LLl lsdots containsL'Lin‘LaiM largelLJI'g: L'iL'111L,elongated:11LL‘1 to[11 5111.1-sub-roundedl'\l‘Lll"lLiCLi piecespi LL‘CN Lil'of dcnwdense mottled111L1illL1Ll limestonelin1L1

QuilliiiOoliths again b'L1L‘11111L1become C\lLiL‘l'llevident in inind—xcin‘m‘whand-specimens from 1-11cabove Milli.)2,000 ft.l1. 1'2'0211from ti]:the l.111Lzbdi1i>iL1n was11m i1111L1s~ii1lL1impossible asa5 resistant1'L‘wi5'1111 horizons,i1L11iz111'. usuallyL1.~11ail:.' exposedL-‘\;1L1.-ed 11*as bandshand: of11!: boulders,l‘LIL lLl:‘"' areLL:'L' separateds'L‘pni'LLIL‘Ll from11‘L11t1 onemac ‘L‘LnOIiiL'i‘another by‘3]: tractst1‘L1L'l< ofL'1‘.F mil.soil, winclimcssometimes L'Lj‘Liiz—cquite xficLwide, 1,5111with no i11Ll:LL:EL111indication L11.of the:1 L1 bLir'cLlburied rock underneath.unclei'nccn'n. Most.\l: of 1h:the visible1 ibis successionN'UiL'L'Ch'ViOll L‘L'nmishconsists QfL'11' a:1 rathermim- monotonous111L111L111111L111< repetition7:;1L‘Li1i11111‘1’of

Specimen‘511L‘L'i'111t1 .1i31/56,. L'Hl‘.collectedl L1'11i2‘Leight Zillifxmiles 11L1:"Li1-\1.-L1»‘1north-west L11of RiRiba, L111on 1.1L1‘L‘,l1.L11'L‘Llweathered 151""surfaces Liirn.displaysaw fineaL‘ L111TL1'11current beddingl1L‘LiLlii1g which1'.i11L‘l isix' hardlyl1'Lii'Lliji noticeable11L1iiL‘L1Lil1lL‘ L111on t'nL‘the greyishLll’i‘_\i\'i'] l.11'L1\1'nbrown .iruhi}freshly fracturediz‘i-L1u'LLE surface,sL111L1L'L. where\Ll1L'1'L‘ iron-stainingii'Lin-Lluinir ini:1 bandsl1LL11Li~ showalmxx' no11L1 concurrenceL'1-11L'L11:L1L"L with1121'11 thel'lC bedding.l1. ' Inin thinH.111 SLIL‘LiLT'i'isection I:it L‘Lll'lcan beb1.“ \L‘l‘.seen thatmL14; fine.L1 recrystallization:'L1L‘:'j.HULL/.Liicn i-X'L'l‘ihas L111encroachedL'i1L‘Li L111on pellets and left5:1"; onlyL111l}.'L".11'1"LL'_lcurved elongatedLlL111L'. iL'1LldenseL L1 bodiesi1L'LJiL1~ Lt'i'tLarrangedﬂgrLl parallel11L 1'LLi1L-'. to'.L1 theI':1L' bedding.L‘L‘LiLl 11;. Dense1—3.:11~'L: bands3:11Liw haveI".L-,1'c also113m beenhccn brokenl1? by11:. recrystallization1'L"L‘1':L~1:1il'/ to leave dense blobs strung L11.out Liinnualong the1hr: ,1..' . '.... 'L . 1‘, _. , 1 _ beddingL1L1LLL1111g Luas insetsl'ihL'L‘w in1.1 L1a finely1111.11 L1iL11l11LL‘crystalline calcite matrix.:111'f\. (i;1.~'L.L'Clastic quartz grains.‘ 13 1."LL."L'L.occur throughout[i1r1111gi111111 theLliL‘ :'L:L‘lLrock butbul 141':are prevalentinrcxulcnt in [hethe finelyilnci'. recrystallized1'L‘L'1'\.'\.'?L1ill/L1L'l lnjiL'I's'layers where11110.1: 1‘13}they 111‘:are concentratedL‘L111L'131111'111L'Ll in zoneslanes parallel1'1111'L'13lcl to”111 the1'11: bedding.iﬁcLlLling. Small“1'1 1'1} rounded1'11L‘1‘LlLrLl blobs,biL‘L‘w. colouredL‘L1lL1L‘11'L1Ll l1j'L1abrown byl1_\' the inclusioni1 LiLixLz'i L'1fof numerous‘111111L‘11‘L‘L1w globules 11.of limonite,i 1‘ L'1.1.L‘. may1111', havel1'_L1.L1 l1L-L‘11been LlL‘1"1::-.lderived from‘ ooliths or ferruginous11% limestone13:1 L‘xtL'111L' pellets11L'.1L'1~ and11:13 occur1.1;;s throughout the thin' section. Specimen 31/57, collected at the'11: ~:1111L‘same i‘L"CL1l"_'v'locality and.1' L: with'.1Li1l1 f"‘L"the same.1 -L' mineral" composition'iiliL'i‘; 11Ras 31/56. is dark grey with'~1ilil red:‘L‘Li mottling:11L1‘1Ll511L‘ 2111iand no11.1 sign~3 :1 111'of banding.l: The red mottling iss \_Lseen under the microscope inas L1111LL'1111'LL..L1Z1~concentrations 12'of iilL‘the ferruginous1'L‘1'1'11L:.1: blobs, like those described\L.11L11L above, and therefore a scavmlzn'ysecondary fL'LLILn‘L".feature.

The first exposureL1 L11L1\1_11"-;1 ofL11 Jurassic.i'Lir' x, limestones'11'1'.\'_L1'L\ northL11 of RibaR'I is1L a \j‘splintery1,191} _yellowish01-1191 brown calcarenite 1\11L1L111L11(specimen 3i31/41)— with1L ‘Ll1 1'numerous1'11L1L yellowLL andL Li ~11Lsome larger i111.ibuff pellets11.11.11» distinguishable on claw:close LLai'i‘L'n'LLLiLiiuexamination. LnLlcz‘Under :l1L1the 111'L.L~:LL111-L1microscope 'Lit-L1the pellets Lli'L‘are hL‘L‘l':seen as indistinct, iron-stainedi11L1L 11mland linsljfinely L'LLLiequigranular111'1111.'.LL;' insetsiz1~L1h1111L1111about 1.1.50.5 :11111.mm. 21L::'L1x:\'.across, inin L:a -.'lL:['LLLiclotted matrix..\. AL\ few1'L11.\ 11fof the1l'1L‘ pelletspullctn ~l1L111show L11'L1‘LiniL‘organic 111'or L1L1'1i1l1iL‘.oolithic structures11'11L1'L'L11'L1s L11'Liand zit'L‘are IlI1L1L1glthought to have been'11-L1L'1‘. LiL'1'i1'L‘Llderived from{11111.1 LLa previously1“ 1‘ 'LfLi.11\'._L LlL1L\depositedELJ'LL‘ sediment.LL11111L11 Son'sSome largerl‘1'__ 1' clear shell fragments1:11:111~ L1»as “Lilwell 1::as L'.coarsely‘.L1~L1l_. L"jx.1i'.‘crystalline LL.1L'calciteLL \L'11~veins Lil-Lare L11111L";~L1L.also present.

r------. n

15'JI

Pints.Pink, tincl}finely recrystalliredrecrystallized limestones are often L'tteou-Jencountered“erred in this part ot'of toethe succession. Specimen 31.:"42.31/42, anan exampleexample otof such a rock.rock, collected tourfour miles north of Riba,Riba. shows under the microscope that the colour is derived from.from patchy distribution of ferruginous globules and specks.specks, which.which, in this case.case, are distributed in an equigranular 11.1os:1i..'mosaic of rccrystalli‘recrystallizedLied calcite and dolomite. Five miir.milesr11 north oiof Rib-:1Riba :1a calciz‘uditecalcirudite was collected which.which, in the haitL'l-sp-L-ein'ien.hand-specimen, is a lightham grej'grey dense rock containi1containing11g Lia11'l1'L"darker pellets and elongated hioh1.blobs. 't'heThe weatheredWeathered surface is meneven more L'iistincti1e:1.1distinctive as the grey lletspellets, which are elongated parallel to the oeLiLli11g.t'01'nibedding, form a 1"reliefLief L111on :1a dead whitebwhite background. tiUnderntler the 111icroscopemicroscope the rock is seen to'to cops:consistst oiof a dense matrix containing small quartz.quartz grgrainsaims and somL11‘1L1somewhat clearer rounded or elongated patches with small dense pellets. TheseFhese patches ham-ehave been196:1 Lleriredderived froml'ront another sediment be'before:'o1e eonsL'Jiidationconsolidation and .'-1r-eare thcntseh'esthemselves caiearenitie.calcarenitic. Slightly higher in the succession,succession. about .1'.‘six\' miles.‘11‘. les north of Riba,Riha. the 1111]}only porousoul‘ous limestone found in the Litira;Jurassicie limestones was collected [1pceinte11(specimen 31.54.17].31/45). 1:It is light pink in colour with indistinct greyish 11'i1i1ewhite recrystaliixedrecrystallized l:1\L1t'.'-.layers imparting ua vague.vague handingbanding to the h‘Lti1d-Spt‘L'it1tel1.hand-specimen. NtitttL‘t'OLJs‘Numerous pin—sizedpin-sized holes dot the weathered :11as well 11.1as the freshly fracturedfractured surface. theThe thin section showsshows aa mieroeoquinoidmicrocoquinoid calcarenite with the shellshell t'rarvmcn'sfragments all arranged parallel to 11theL bedding and with chasedense and tine.finely IoLry-s'tairecrystallizedlizcd pellets in :1:1an Lotiigidlttnaequigranular mosaic olof L'ulL'itL‘calcite and Lloiomite.dolomite. Thelhe L:11'i'.:L'11cavities in the seetiosectionon areare nearlvnearly all lilinednetl t1_1-siii1l1by slightlyiy coarser carbonate crystals and areare nearlg.nearly LLi11always111's elongatedelongated :1e1cssacross the strikestrike of the bedding. This secondary porosity no doubt de1eiopeddeveloped duri111L,rduring L'liagettcsis.diagenesis. The discovery of a porous rock of this nature in the .ltitLissiL:Jurassic liniestoneslimestones hashas not been describeddescribed hei'ore.before, butbut the discovery of oneone such horizon, although thin.thin, points to the possibility”possibility of more such horizons in poorly exposed parts of the succession.succession, and is i‘.1.1port:1111important when consideringconsidering the possipossibility' t_\' of the occur- :'en-L‘erence ot'of oil in north-east Kern-a.-Kenya, The gt'cgreat:tt majority111ajorit_1' ot'of the rocks collected in the upper part 111'of the Bur MawMayo Lime-lime shines.stones, atalthoughhough it is not 111111115always oh1iousobvious in the hand-specimen,h t—nd —soeci111er1 are found to eonl'Ltincontain pellets when examined 111icrosL‘1microscopically.neatly. This also applies to tossiiif'eiousfossiliferous horizons such :.111as are represented by specimen 31.548.31/48, collected .1'L11'e1'.seven miles north 111'of Riba,Riha, in which numerous fossilsFossils and shell t'ragittentsfragments are cemented in1'11 finelylinelt' i'L‘L‘r1'staili'zieLlrecrystallized carbonate also containingContaining some coarser L':‘crystalline‘Iali . L' calciteC1. L.te and smalls'rtali Ll-Ldense11.1'c pellets. Evenliven oolitesooiite1 L'onzaincontain structureless pellets,pellets. as in111 specimen 3131/494‘4 from the same localityloulity :11;as 31:414..31(48. 't'hzsThis ooliticL1oli1ie limestone,limestone 1111.11.11apart from' havingit; 1 hunter-.1111numerous partlypa altealteredred and 1.11:1LtisiL-1'sometimes flattened o:ooliths,iliths hasl111s211a111's111aiermany smaller sub-rounded dense pelletspeliL and.mLi 1:.allsmall shell t.fragments,aatit'Lhts sometimes with ooli-ticoolithic ri:1....L11c.-LJseLtrims, enclosed in '.1a 1'ec1'1-'s"L1lii'/.cLirecrystallized calcite 1.1111111161111153.groundmass. Inin the .hand-specimenl1'LLr11l-spL1'L‘i111L111 flattenedtlattene: ztrgillaceousargillaceous limestoneli =11L‘11 pebblesp 'ohles occur along zonesrunes parallelparatl'e to1.1 the 1;vagueJoe bedding oi"of ihethe rock.ro'L‘l1'.SLJ-L‘hSuch pebbles were also seen :11in the rocks eight mil-L'smiles north1.. of Riba.Riba, 11hc1eswhere soeeispecimenmen 3i.'.iti31/50 11:11was Lcollected.o-l.L1'L1eLi 'i'h;'1'This i-z1s1'iiit'ero'1‘fossiliferous calearencalcarenite...- has patches of1 recrystallizedI'L‘CI'}-'Z~itéllll'/T'Lt;l carbonateL'::111ai.11ir.1.gcarbonate containing small giohulesglobules oiof h'L1111:.i111ehematite :ha‘.that impart a.1 distinctive'1': spotted appearance to.to methe ."o.,lL'.rock.

In111. cor-Slitat'isoncomparison with'1131i1i-l11the underlyingordeii‘ mg .l.Jurassic11"L-1ss' ..' sediments,sLLii' .L‘ots. iti'. can hebe noted that porce1-porosi- lanous'.:.-'.1'.11.'-s and 1.1“.iL'i'L'tCL:L1L1itiomicrocoquinoid limestones are much more abundant.1L’_i'-111t iiiin the upperunoer part of the Bur Mayo-'o Limestonesi.in1.-est1.1;1e1 -and that the typical arr-.1grey argiiargillaceous.. .L'.s li"-=2s'limestones,tones. so prominent in the =.o11e:'lower parts,Torts. :11'1‘are virtually\'1‘-?.L1'.Lll}. 'Lt'osentabsent aboveov: :.i—1th)2,500 l't,ft. 1111-11from the base.Lise. 'iheThe .l-Jurassic'.11 'ass'ic limestoocslimestones 1'.iof 'LtheL1 \Vaiir'Wajir 3.1""area do:L‘. not reach so l'tli'far to the north—ei'Lstnorth-east LL1-as too '11.cl1.L'...1‘Ll1einclude the 'L).si'o:':ti:1r1”"Oxfordian" Limestones' of Saggerson :=.11-.L'land Bakerlinker t'l'iih‘.(1958, pp. 16-18).111—131.

(c)[1 '1 51:11:11:STRUCTURES1131.1 IN1.\' THE”1'11; JURASSIC.l1.11.\s.stt' LIMESTONES[111115111315 InIn L111an El!'.."..tarea '.'.'hL1:'L'where 1'.-'.1outcropstops are r'L'Lrei}rarely encountered.encountered, such as ;1[at Wajir,W: "'-.r. it is only to be expectedeeteLl that zones orof strLstructural{oral weakness11 eukness would 1111-1not be exposed. Several stl'L1L't'Lstructural features,-s houevcr.however, were recognized on aerial photographsphotograi'u'm 'L'Il'TL‘iand subsequeittiysubsequently sub-siding"substantiated

-- -- \. ~ " - I l " — ‘- " __ '7/ .______....._:_W2°00' N. rOO-;N. \x '", \/ \ / WAJIRSHEET(part) i1 '" 1: WAJIRWM BOR SHEETtr-T (part) //'" / Q - \ P x ‘ as: . .. i \-1I _; \~.-,\ o‘ ‘ ~I' .-_-‘ = t‘ F / f; ”P, I \Gajaja\'6 / I '6 I \ \ "F/ ...0 ll,. \\Gdlald\\\$\ ,,,, \\ \ / ‘ 1:; ‘y - > --. ‘\ ‘i F ; l,\ \ \' ,...\- \\ \\ 1 ‘ ‘ I I !, \ \ F \ \, / ,\ ' /, I I I / 1,I \,, I I \ /A “n ‘ 1 ‘,I \, / I "' ,\;t\ / 'v"\\ .1 FlAre.'mall/olcl,.miframa‘;of'..\,/'\, f" M!.! \i '‘ I t . .\ x‘ 4_I mum rm \ r / \ I F / \\ /' !- \)(' '\. “who"rf~~t~“Mfg-FM“to' ,‘\ 1YF \ , I: ,1 ,1 “\ ﬁr/ 1 I \,,' Shande!;Sh;andorn1Ot/r ‘ ~ \ w I I i I \ ~;0/.-.as!, \, ::,.,I \ \ " / \ t 1 ",‘\ / x.'"XX \ :' : / "" / - I 1 \\ " 7 \| I I \ I I \ / I I I / ; , 1 “~" \\ \‘f/"<' , / ,(F A I \ "H \I \-\ \ \ , /1 '- "", \ ""-m. -. I,v \ \ \ 1 \ "I \ \ "-<", x / :| \ \ I \\ \-, / "'" \‘x' ~/~'" fruqeMuge 1 I ' /r \ \_ /r / \ \ \ \ , ' F ""'5' I " I I \ ' f: ‘\x. \ , I t \ ' /' \ F '. \ I , I , ' X \ I 1 I \ I I I I \ , \..' \ "'-"'/ \,F " ", I \ " ' Kurso/e \ II_\!I \ \ , ,, ' ' ,~ \, , ... ",\ f -9l \ /' "" ", ,/' \F 0\ \ \ " " ", 'I, \, ~,f \ \ , '..... /' \/ r F /\ " ", '"t '<;'F ..Q /- \ \. ',- r-,"""'" " /" " '''''' ' OI~. ,,/ \ \ "\, "'" LF I.F " " "'... ' \, , " L "', F-'" \ \ \ '" I " " IF F ‘ 1.550e,OSO'N. So'N. 0(" .. \ '" , '" \ '. \ ',t: 7F" "'-, /...... , '-'F ", '" IFIF Fauhs .x” Darectmn of dlp '" -(" Faults Direction of dip \ \ ' ,':-. "''''''' "' -- _.« T or o~', "" F',,/' """ , " Armchna! :1s ___~—'-", Trendrend 9fof beddmgbedding Forog g ",," ", Y", / \~i" \ . ~ Anticlinalaxis --' (Durectlon(Direction of strike) \ \ ",If. ", F F" g Synclmal axes ~ '" """.d1' ", I "'-, J ~ Synclinalaxes 0''" ''-'" "~ "<"- ' t.! ~('.r " ...; °.r . IF "" '" u v 1 w A s s x a 9 m N‘u 0 ?I—A—IlAlh-AU! ~' ~ ~ ~ ~| ~I ~I ! '.0| Mn.. [;" 0 ~ ...... 0

Fig. 2-Structural2---Slrllclur:|l munmap ufof the Jurassic.luruwic lilm'slunclimestones,ﬁ. WajirWMII area.‘ll't‘ﬂ ~ I

in the field and are shounshown in Fig. 2. Apart from being evident on the aerial photo-photo— graphs.graphs, the strilsestrike of the Daua Limestone Series is relleetedreflected in the trend of ridges formed by resistant horizons and by the scattered dip measurements. '1Thehe bedsreds are seen I to form a broad arcuation with easterly dips in the north with a gradual swing round to north—eastnorth-east dips further south. base of the limes-tones- is nearly l.lt'tt1 it. above sea—level at (Jaiaja ~( Faults.-TheFaults—The base of the limestones is nearly 1,100 ft. above sea-level at Gajaja and less than 900 ft. south-east of Forogorgor,Forogorgor. and consideration of the topography and the dip and strikestrilxe cfof the limestones indicate that there must hebe dip—faultsdip-faults between those two localities. Two'l'w'o faults striking to the north—eastnorth-east are posttlatedpostulated to explain the I structure,structure. one running along the valley south of GajajaGaiaja hill and the other north of Forogorgorl'iot'ogorgot' where they are presumably responsible for the oil-settingoff-setting and strike varia—variations mapped. InIn the areas where these faults occur,occur. esptistiz'esexposures are non-existentnon—e\isten: hut.but, apart from the change in direction of strikestril-te of the liinestones.limestones, they also have topo- graphic expression init the elevatedelevat’ti areas to the north of the faults.faults, Itl: is considered that horizontalhoriZontal movement was responsible for the curvature of the beds as indicated on Fig.Fig, 2.3. The'l he fault near Forogorgorl'orogorgt'tr has greatest displacement in the south-west and gradually disappears towards the northeast.north-east. The downward movement on the south- east side of this fault is also espressedexpressed in L:a widening of the outcrop width of the beds east of Forogorgor,Forogot‘gor. which is thought to be due to a.t decrease in the angle of dip of the limestone beds in that area. Other faults indicated on Fig. 2,2. were taken from aerial photographs on which they appear as straight lines across the strike,strike. and usually shcv.show slight horizontal displacement. '1Theyhey are generally ol‘of small magnitude and lose them-them selves in minor dedeflectionsﬂections of the bedding trend of the limestones along the strike. Inin the field,lield. faulting isis. recognized by cross-cuttingcross—cutting zones of recrystallized'ecrystallized lime—limestone,stone. irregular lumps of clear calcite crystals in limestone,limestone. or by sudden deviations of the strike. Coarsely recrystallized yellowish and pinkish brown limestones occur along cross-cuttingcross—Cutting zones as smooth brown boulders which display their coarsely crystalline nature only on fracturing. UnderLinder the microscope these rocks (specimens 3131/21,2]. 13/2513.25 and 31/58)31 581 exhibit large replacive pools of carbonate usually dense with evenly scattered grains of limonite. Inln specimen 31/25,3| :5. collected 3t.)30 miles N.N.li.N.N.E. ot‘of \Vajir.Wajir, the matrix also encloses detrital grains ofol‘ quartz and calcite which were not affected by the recrystallization. SpeoimenSpecimen 31/2631 926 was collected 30 miles N.N.E.NEE. of Waiir.Wajir, and contains large and small angular blocks of dense dark grey Limestonelimestone scattered in a large brownish grey recrystallized matrix. The dense angular fragments are distinct on weathered surfaces and give the rocks the appearance of a breccia with widely spaced fragments. These'l'hese rocks do not form a continuous horizon along the strikestri'se and as other indications of faulting are evident in the area.area, it is thought that partial recrystallization resulted on fracturing. A commoncommon feature of the JurassicJurassic limestones.limestones, especially in thethe eastern parts.parts, is thinthin clear calcite veins traversing the limestone boulders. The veins are nearly always perpendicular to the bedding ot'of the boulders.boulders, which indicates that theythey are vertical or nearly vertical.vertical, and in outcrops or boulders found in shit.situ, the veins strike north- I easterly which is thethe main strike direction of thethe faulting. inIn rocks where chalcedonic 'I nodules occur. chalcedony is sometimes found within the veins with the calcite. I~ nodules occur, chalcedony is sometimes found within the veins with the calcite. I Clear crystalline calcite sometimes occurs as lumps and stringers in the limestones along faults. About one mile north-east ofot‘ ShandermotShantlermot where small shears occur along the edge of an unexposed fault-zone,fault—zone. such a crystalline calcite mass can hebe seen on a fault—planefault-plane as shown on Fig. 3 (to.(a). 'lThehe strike of the fault—zonefault-zone is 2020° NE.N.E. and the strike direction of the small shears make an angle of about 50050' with the strike direction of the main fault which passespusses to the west of the faults shown on the plan. Horizontal displacementdisplacen‘tent along the shears iss very small. 'lheThe angle of dip of the beds increase towards the west as the :nairmain fault—Zonefault-zone is neared.

I r

/ / / / / / ~~ (a) I / - "" / / Resistant --- "" t -- "" /\:.':'-- ' /.-:::-/-~ //-': );~:=:::::-I "" ",,/---"\ ",,/ 7. -- /.-1 ~ :;y' /~--" I /./ J'/I' // 7 /" ~y .--'--' '? /:// f!Ii.~C /~'/ :::0-;:::;-:/:/ 1mest one horizon J . /'-- I ~~~:",,/- Ic~;;;::/j/- / IF / ~~~i:t:':~h Ilmostone v 25_. 50- :575 mo100 FmFeet / I... I.. I.. Ji l FI lF ~F 0L i

I.'i

~~,:,<0,., , (b) (c) i ~';-~"'/ "":-. \ FlaGs of re,istant , ( Resistant IIme'' tone lim~'tone horizon hOrizon ":-. t -=~, ''::::: j , Soil /-:;:. ~ -:;:./ r- It \\ ~~ ~:::::::::::"_-"'-"":::::::-..I Domed limestone 1\ )~~,'~ "Kl-,,\\ ~V pavement I) II \~'\\-- ---! V \~\ \-- -;.\)) --- ~::::=:::::.-- \" '\''- L.- II //" ~ ~-- -~ "'~" --:::/ '::::::--- 0 5 "' 15 20Fe., -T L J. I.. I.. J 0 5 10 15 20F.., I.. J. I J J

Fig. 3—Skt-lc'il3-Sketch plans of structures inin {lit-the Jurassic Eimtsirmcslimestones

Folds.-Small1403135; Small foldsfuzilu's 01'of (myany coaiscLlLicz'i-.‘cconsequence {indo not axis:exist in llzcthe Jurassic limestones,Eimcstoncs. but thanthat minor plicationpiiuatimi did take place can behe dcducccldeduced fa‘omfrom increases in th:the Emgl:angle of dip.dip 4ndand frumfrom (iuczlsEonziloccasional scum—westerlysouth-westerly clips.dips. An increase in the a:angle{is of dip is obvious wcs?west of Kursoleit; lc and locates a s0uLl“.-L‘asl—north—westsouth-east-north-west synclinaisynclinal axis in that area (Fig. ’11.2), but the['l‘ paucity of vapor.exposures to 13wthe mmhnorth and south {11‘of lbsthe synclincsyncline preventspres-ems the locationiOL‘ﬂliL)‘ of adjoining anticlines.aniiumes. The folding inin this arcaarea is probablyprehahl} the‘ reason.un for the111C wideningWidening of the outcrop width ofCri- the[he noli‘iroolitic zone7.0%: there,mere. whilew. .c the cause foriL'EJ‘ foldingfokiing mustmus‘i be sought in ihethe situation in the wedgcwedge betweenbclwccn til.)the faultftmli north ul‘of ForogorgorForogorgm' and 1tthe fault-zonei'étLilt—Zi'ri'm north of Khorofix'hurol‘ Atat.Aiall.

1 SleepSteep ;.dips3 weremm racoz'aicdrecorded in theHis area northeastnorth-east 01'of Shanda-ma:Shandermot wherewhore. lowinw sum}southerly alipsdips are also encountered. The dome shown Enin Fig.lug. 3 Lid}(b) 0;occurs aboutbout motwo :nilcsmiles norm—north- ms‘least L31"of ShamicrniciShandermot and explains thethe L‘i‘l‘;l."éll'_\'contrary dips b}-by miidmild 'mxmmgbuckling of {hethe limestoneslimusmncs il':in small Liv-min.domes and saucer simctuz'cs.structures-

-'-- """,,- ~ . - 51

SaucerHuuucr structuresNII'HL'HH'Ch asin \hounshown in Fig.i-Eg 3 (c)l:‘) are quiicquite commoncommm in the limestoneslimestuncs and are usuallyI3- formedi‘vmzud byb3, ftaggyHawk limestoneiimuwionc bouldersbouidcrs in the1h: soil,xvii. .151all dipping inwardsinward»- ;;'.at varying angles.1 In the vicinity\iu ii 1; ofHI ShandermotKhimdcrmnt where\xhcrc the dipdips are normallynormaliiy low,hm. they[Inca are presumed toin occurO.‘\.‘LH' asLu theihL‘ counterpartununicrpm‘l of0f theihc domesdUIHCN as11$ shownShi'mn in Fig.1-" 3 (b),rs"). buthr. in otheriiiiiut' areas[LJ'L‘Zi\ where\nhci'c theirEhcir components“iiiipiinuntx usually:ix‘Lmii‘, dip steeplysic-cpl} Inc)they w":are I}thought‘ to:ii have,3»;- resulted."c<;ii1-.‘Li by1‘) the[ha collapseunlinpw ofdi- subterraneanxizbi_i‘i.ii‘cun channels.5“ x‘ in theihc limestones.iimcx'hincs. Tit: "Ulh‘iLAI-i‘ﬂ K i'qizgi Tim: m; 32113 {MILL-m of 11% .liii'mwxi; ii-z‘i- \1 Synthesis.- The conclusion is reached that the fault pattern of the Jurassic lime- I stones“ w of.‘t' ihcthe Wajir\Vuiii' areaLJLL: isi~- I'nuthe expressionmm'mxinn nnon the1h: surfaceairing: ofu? Liccpwcuicddeep-seated ‘M‘Cnchwrench faults,{1:111:51 and that the'hu shearsxiicurx andism small\H‘iiii folds{with are.irc manifestationsingiiii‘cﬁatiutix ofnz' theinc re-orientationI'C—UI’iCHI.LIiU]‘. nt‘of stressRUIN" or differentialcz'ciiiiui movementmmsnu‘nt along iiicthe Inuit-whiny»fault-planes.

3. QuaternaryQuaternary. Sediments

SuiimcnhSediments ni'of (‘);i;;i:;:'nuij.Quaternary armage occupymum} incthe majorimijur panpart n1of Ihcthe arc-marea, i:_\gii.di:‘.gexcluding uni}only the iiui‘lh-L‘cnti'ulnorth-central acum-sector \tchwhich isix m‘cnpirdoccupied 113by theiiic DauaDana LimestoneLinimmnc SCI‘iLN.Series. The dating 01'of the dcpwibdeposits dL‘pCzidsdepends mion uut‘i‘uhxmncorrelation niihwith Vmiiar'similar bcd‘beds in thcthe DamDaua mile;valley tnto ihuthe :ii‘i'Ihnorth and the \ii'ziiigb'apni.;iistratigraphical pmiiinnposition nucupigdoccupied ii".in i'L‘iJiirelationﬂn into thcthe cnci—Tm‘tiuz‘;end-Tertiary pcncpiaiii.peneplain. iii-cThe cimsiiimiinnclassification :niupicdadopted in thisihix reporti'cnui'i ix‘is Umas i‘Uiii‘i\\\Ifollows:- -.------I Recent I River Soils Recent ! RHL'.‘ Soiix L'mwi RedRad and brimbrownn claw)clayey milssoils xxiihwith CLliCJ.1'L"ULlScalcareous nodulesnoduics J I Upper {ire}Grey Lindand bi‘dCi-xblack soii:soils ThinHim laminatedlummutcd limestoneIimcsmnc Middl: Ferruginousi-ti‘i'ugimms mil-idstoncssandstones :mdand mngiomcmicsconglomerates Pleistocenei’icwuk‘cnr (})‘psitcGypsite and g}gypsumDSLLTH Impureln-murc limestonesIimmtoncs i —— _. ‘-\\:i_iii'Wajir BedsBcdx‘ I Middto 1 SandstonesSundxmncs

! Lowerhmu‘ (?)i ‘_’) Clays(“lay and mmdxsands J -----I ------

(a)rm WAJIRWHIP: BEDSBun

Encirclingi’_'_'1..':l".‘iil‘.:_' 1hrthe x;sediments"ncnix miof .iiit'a'xxicJurassic L-iageg: LH'L‘are ihcthe Wajir\\itjfi' BedsBciix‘ (Pai'kinwn.(Parkinson, 1920,[93.1. I x Wajhir\\'.i_'hfr Beds,Buds; p.3‘. 111: eti'.’ seq),\i‘uL which“fifth consisttom‘s: mainlyn I uin'; of white“him Into greyare“ laminatedlaminzi‘icd impureiiiipuz'u limestones_ 131‘a Eliand gypsiferousgmwiicr‘um beds,huh, 7h;the pi'ucnccpresence nI'of them formerI'nz'mci' bcii‘beingfl. indicated in}by kunkarkunkaz‘ limestoneJIIEK'HU‘I‘JC unwrappingoutcropping in the red'cd ‘x.iI‘.Lif,sandy soil,mii. while\tiu g1»gypsumpxum is ind=indicatedaicd h}by light or dark greyui'cy soilmil containing numerousnim‘icmux calcareouscaicni'cnux noduicx.nodules. YYellowishimix‘n Into lightiighr grey.grey 10217119:loams forming ndi'lpart 01'of the{it-c Wajir\\ iii ' BedsBur ~ Lii‘care sometimeswiticiin‘xcx \csnseen in vii;circular1' depressionsdcprcssinm in thcthe xiginityvicinity 0fof Wajir,ir. whileMails qiiziri/iiicquartzitic ornr felspathici‘cispiaihi; sandstonemuln‘iflnnc cobbleswiwhice andimd pebbles in ahcthe Snaurwariu-Saturwario- Libiduli. dii‘i' areacu muindicate'2?“ incthe presenceit'cacnqc of uni:sandy hi'vi'iénnshorizons in In:the \CLIUCHCC.sequence. To Incthe nm'ihnorth of31‘ Wajir the Wajir Beds are; meroverlainfiin by11}. partlypk ii)” indLJx'nlcdindurated fi‘i‘I'uginuuferruginousfi sandsmncs.sandstones, Minnasome- timesi'mcfi mniucontainingfln-v pL‘DbiL‘Npebbles derivedLici‘fxcd i'i'umfrom them: Mum-:1Mansa (mmGuda Formation.Fomhdinn. Patches[’azghcs of the conglomeratic\mci'uiic icz'i‘ugiihferruginous.h sandstonesuii‘.ii\h\i‘t‘~ zippciii'appear anon in:the \‘xmii‘fWajir BedsBeds” further wiiii.south, CEIN‘Ieast of Wajir, and 131::ifinally disappear‘11!" underLimici' {hethe gm;grey \‘niixsoils in [hethe mmhcrnsouthern partpurl of methe tLl'L‘i—l.area. The easterly extension of the \\_1_ii:'Wajir BedsHudx formsfin—mix .ta ribboni'in iwi‘wccnbetween theiiic .iElf.:\'iiCJurassic ;in‘cxmnculimestones mto the north and theinc grey:1: soilsm9.» into the1h: minimsouth.

Because of the prevalent'«Iun‘. redi'cﬁ soilxvii cover“mgr andid ‘iicthe presencepi'txcncc miof Mini-airkunkar limCStnnc.limestone, iii:the true nature of the Wajir BedsHQG~ cannot be dmLidetermined.1'31cd mion Ihcthe \Lll‘fiiL‘C.surface, but cummun»,excavations, and quarries as well as the numerous wells ini“ the[h \\.i_i‘i'Wajir iii‘u‘iz.area, providedNmidcd inim‘n‘izltkminformation on

.- I '2020

theshe upper parts of the beds.beds During 1952-531953—53 Bestow (195.3}(1953), while conducting an intensive study of the geological conditions controlling the ground-waterground—water distribution in the area,area came to the conclusion that,that although the WajirW ajir beds vary\-ar3 greatly in thickness and lithology both laterally and vertically, a fairly uniform succession exists within the well area at Wajir as follows:—follows:- Thickness feet 4. Semi-friable laminated impure limestones __ .. .. ._ 0-12 3.(§1‘ee11ish3. Greenish or reddish,reddish. calcareous or ferruginous sandstones ._ 5-205—20 2. WhiteW hite or grey calcareouscalea1eous loams and marls.marls ...... _. .. 10-3010—30 1. Gre3z1renaceousGrey arenaceous cla3-'clay [at(at Waghalla,Waghalla 8 to 9 miles west of Wajir) .... 30

The logs of the bore—bore-holesholes drilled at Wajir du1ingduring the W'Ettwar do not appeappear1r to be reliable, but indicate that unconsolidated arenaceous clayscla3-s underlie the above succession to a depth of 150151.1 ft. On011 the Tarbaj road,road. IE116 miles north of \\Wajir.1311: atesta test hole disclosed the following succession (Bestow, op. cit.,1:11.. appendix K):-K]:— feet 5. Surface sand .. ., ...... 0-50—5 4. Red friable sandstones ...... 5-95—9 3. Highly arenaeeousarenaceous white limestones ,...... 9-509—50 2. Calcareous and gypsiferous loams _ _ ...... 50-8050—80 1. Highly calcareous white sandstones with yellowyellOv; mottling . . 80-8580—85

Further to the north,north. outside the area under discussion.discussion, another test—holetest-hole in the vicinity of TarbajTarhaj gave the following succession (Bestow,(Bestow. op. cit.,cit. appendix K):-K):— feet1'36.” 7. Surface sand . _ _ _ ...... 0-6 6.(1. Red ferricrcteferricrete _ . .. ,...... ,. _ . (1-206-20 5. Red sandstones .. ., ...... ,. __ 20-25205-35 4. Pink fine-grainedfine—grained non—calcareousnon-calcareous sandstones with white mottling 25-71 3. Yellow calcareous loams with pebbles of loams like those of Wajir ’Fl—Bt}71-80 2. Damp yellow sands with loamy bands .. ,. _. .. 80—9780-97 1. Damp sandy clays.clays, pebbly in parts ,...... _ . . 97

A pilot well at Waghalla, 8 to 9 miles west of Wajir,Wajir. disclosed the following sequence (Bestow, op. cit.,cit, appendix K):-K):-~ feet 0-6 8. Surface limestone ...... 0-6 6-22 7.7, Reddish sandstones ...... 6-22 22-42 6. CaleareousCalcareous loams becoming less calcareous downwards . . , . 22—42 42-52 5. Grey sands with calcareous nodules ...... 42—53 4. Grey calcareous loamsloatns with calcareous nodules ...... 52-6252—62 62-91 3. Clays..Clays __ ,...... _ {13-91 91-92 2. Clayey sands ...... _ . . ._ 914)} 1. Sand ...... 92-93192-93%;

~ . "

At Canon.Ganuri, 12 to 13 miles WSM'.W.S.W. of Wajir\Vajir and nearlynearl} 10 miles outside the present area,area. the followingtolloxting succession was obtained lBestow.(Bestow, 0]).op. (it.cit., appendix K):-Kizw jije’ffeet 7.ThandSand .V ,...... _ ...... 0—40-4 6.(5. Gritty limestones .. ,...... 4-41 5. Grey clays ...... , ,. 414541-45 4. White friable sandysand} limestones ...... 45—5445-54 3. ClaysClays.. .. .,.. '...... V. ..Vi.\ ...... 54—7054-70 2. Argillaceous Dret'ish—ye‘ilowgreyish-yellow sands ...... 70-78 1. Pink sandstonessandstones .. . V ...... 78-837&8}

Bestow (his appendix:ippendi\ H)HI also gives the analjtsisanalysis of the argillaceous sand occurring at a depth of 5253 ft.it. in Well No.1No. l at Ganuri,Ganuri. where“here it is the aquiferziaquifer:- % Si02SiOV . . 74.577457 Alp:!A140‘ and Ti02TiO‘ 3.328.82 Fe20aFeBO 3.47 MgOMgo 2.19 CaO V . . . {1.580.58 Moisture at llt)’110° C. ..V V V. 7.577.5.7 Loss on Ignition at 900°900' C. 3.46 Cl 0.0?0.08 SOa80} 0.23

100.97IU().97 Anal: Industrial Research Board,Board. Nairobi.

From sequences given it is clear that the succession is highly variable from place to place,place. but this feature becomes even more marked when the sections of groups of wells around Wajir\Vajir are studied. Laterallateral variations in the sediments are found within a single well group. The lowerloner parts of the Wajir Beds are not exposed.exposed, but the occasional pans in the area showShow yellowishyellonish and light grey dustydustt soilssoils: whichnhieh may havehaxe been derived from the loams in the lower beds. InIn the Saturwario-LibiduliSaturwario-IVibiduli area several pans lined by surface limestone contain boulders and cobbles of quartzitic or felspathic sandstones. The deposition of the sandstones may date back to the Tertiary,‘I'ertiary. but the stratigraphicalstratigraphic-.11 position agrees with that ofot- the sandstones usually underlying the limestone in the Wajir beds. The quartzite (31(31/32)32) is pink and faintly banded due to sorting of the quartz grains and contains aLl number of red-brownrcd—hroun c113.alay gallsgulls flattenedflattened paTallelparallel to the banding. Under the microscope the clasticelastic minerals are seen as sub-angular to rounded quartz grains.grains, felspar,felspar. mica,mica. hematite,hematite. limonite,Iimonitc. chalcedony and tourmaline. The grains are usually closely packed and cemented by secondaryseenndar}. quartz.quartz and opalineopalinc and chalcedonicchaleedonic silica,silica. the latter minerals displaying a fineline handing.banding. The quartz grains are fresh and sometimes contain numerous small inclusions,inclusions. while the felspars are altered.altered, usually to dense brown material and finefine calcite. The plagioclase telsparfelspar is oligoelaseoligoclase while microcline is the most abundant of the potash l‘elspars.felspars. Both muscovitemuseovitc and altered biotite are present in the liner-grainedfiner-grained bands.bands, where the fineline dark minerals are concentrated. Individual grains in the quartzite range in size from (1.150.15 to 1 mm. across. The sandstone (specimen 31/3231‘ 32 (a))(at) is also pink in colour but is mottled with light yellow,yellow. and is flaggyfiaggy with a sugar}sugary texture. Sorting is also distinct and red-brown clay pellets are elongated parallel to theit e bedding. Surfaces along whichnhich the rock splits shoe.show numerous small flakesflakes ofot‘ mica.mien. Microscopicallyhilicroseopically this sandstone resembles the quartzite described above but is not so well cemented and the cement consists only of secondary quartz.eiizartx,

I J 22‘1'1

DixeyDixcy 11“)—i.\_(1948, p.11, 10)1111111111111found 1.11113only surface\111‘1‘11L'L‘ 11111cs‘11111L‘limestone in111 111Cthe wells C\Zii‘|11examinedﬂC‘L1 by1‘} him,111111. but1111'. although111110113411 1111Crbc1L‘L1interbedded limestone11111611111: is1»; abacmabsent 111in mmcsome \xL‘11Swells 111at El11151161Shelati,21. and 111in 111L‘the pilot well11511 two11x11 miles111119: north11111111 of111' Wajir,\‘1‘z1j11'. 111Cthe Lucrageaverage 1111\‘knc\\thickness of 1111:the 1111113810110limestone 1:1in the11‘1L‘ \VajirWajir BedsBt'd“ is about1111.113, 5 ft.1‘1. 11%Ls1.1\1_.1_,n.(Bestow, op. 1:11..cit., p.1‘. 10).1111. In1:1 111L‘the Lj11.11'1'1L‘

”1:211:11detrital L'211L‘11L‘calcite 111L11‘L‘111L‘indicate 111111that 1‘1111bothHob“ 111Cthe BasementBLISCIMCHI S1System\Icrn and 111::the .111:".1<\‘L'Jurassic limestones11mL‘x1111‘;L\

L ,

contributed.117111'1‘161‘11 to11'1 111.-the compositionC111‘1g‘1'1s} .111 111‘of 131Cthe rock.1‘ 1.1.. SL-c11111111r').Secondary banding1".1111'1111 rr: consisting111111 .1.‘of ~.1,1L'L'L'L\1v..successive

E: 7—7 crystalline<1..111:‘1L‘ calcite:31. IL" .11111and 11:115L‘dense :11'g111uL'L‘wmargillaceous carbonateL‘1111‘1111111L‘ 1L1\t‘1\layers is\ 11.1noticed in the1 f3 1;.1}'~.11.‘11'1recrystallized calciteLL11L'1.11c 1L‘111sveins 111‘or 11111111;lining solutionmﬁutinn L'111111L‘x.cavities, while11.1111: L'11r.1:‘.;1~:coronas .11of 11:.1\\1.1recrystallized111/3311 L‘;1:"s\1t1.11L‘carbonate rim111.1 the clastic.1218‘.‘ L' grains,131131115. with\11111 111‘.‘the width1\1L1‘.11 of(11‘ 3111'the .1111‘1‘11.LiL‘1‘L‘11.§C:11corona dependent 1111on 11“.»;the \1ZCsize 111‘of 111L‘the {3.111.grain. The111:: 11111L-x‘11,111Lxlimestones 111':are 131-111;being :111L-1'L‘L1altered 1.1to ~113‘1L.1§L'1:1Tsuperficial 131limestone at.. their upper surface and nodules:10d111L‘x' of1111 1.1111111,“kunkar .11‘L‘are 111,1:‘111111gforming 111in 1110the ‘011soil cover. This alteration“1111111 .1of 131Cthe limestone destroys115111115 the111: buddL‘dbedded 'Li‘C'dFLiDL‘L’appearance 111‘of 111Cthe 1.1L"...rock, 1119which then becomes 11.11.1113porous 11111with 11‘1‘irregular darkerdarkL‘z‘g1'L‘greyL-_\' g1'cusy~1.'1.1k1nggreasy-looking putL‘hL‘xpatches 1'<11L‘L'1111L‘n(specimen 3131/62,,. \\.1111‘1.Wajir), 31111and 11‘.at 111Cthe \111‘1‘;‘.L‘L‘surface bL‘L'nmL-A.becomes dense g1exgrey \twith 11'1LgL11arirregular da1kdark \potsspots andand 110.111lighter L'.1E.1'.11'cdcoloured pnmuxporous 1141.110patches lspL‘L‘Emcn(specimen 11‘31/61,61 \\;1ji1'1.Wajir). In111 .111111‘.a thin \LC.section11111 111‘111121411L.“of the latter rock111L1L111L‘1L‘111L‘there are 1111111L‘11111Lnumerous \Uh‘dngsub-angularﬂhir quart/quartz grains,graini. SOIHLsome 1‘Lfelspar1\p'.1r1r;1g111L1‘11\fragments, 31111and chcr'tchert 1.111131%grains in .1a dew.dense 111111111111"nodular L'111L'L11'L'111mcalcareous 1:1;111'5matrix. DenseDLnsL‘ brown13101111 irregular:rrLg111'11' 11011111.;nodules 11.1.-are 1111111111111.probably L'.1111p.1\cdcomposed .11of .11‘111111L‘opaline 5111.1silica with 11111.};much iron.111111. \ugxVugs in:11 1hc111211the thin \LL'zinnxsections 1.1Lare 11111.11lined by1‘} 111111thin Sayerslayers 111‘of L'1L‘;1,1‘clear L'L1'1L'11c.calcite. The1hr L'hL‘r111L‘111chemical 11111111911analyses 1'11of 111L‘

C110Cao .. _...... i 39,72“19-7 - 35-5625'56 Loss1,11» 011on 1g1111é011ignition ...... 34-234.22 24'7824-7? :: I Total..1111111 . 995599'55 I 100.3410034 .. I 3131/61-Kunkar()1 , K11111L'111'11111L510n1;limestone, \\Wajir111 township,1011: 1511111 .11at \11:surface.1.113.: 31/62-Kunkar31‘1’12777Kunk31‘ limestone,11111L‘51011L‘. \‘111’111'Wajir 101111511111.township, taken1111mm sewnseven feet1.11:1 below1.161.111 511111103.surface. Analyst:11.11.111.11: J,J. Furst.1511151. Further1'111'1hc1' 111to 131Cthe taxi.east, at:11 Wajir“211:1 BorBo" 111111and Riba,R1b:1. 11L"the limestones11111611111“ rest1*.«1 11:11.11}directly .1'1on 121.-the Jurassic111:".15LEL' «dink-31:4.sediments. 1511131L‘11Isolated patches1‘211L'11L‘s 111of 1.1111131kunkar 1151‘:C\1011C\‘limestones 1:1L15CE11L‘indicate 111Cthe g‘m1111111position .11of hollows11111101“ on1111 theihc ai-‘I‘L‘rtiamend-Tertiary peneplainpL‘nL‘p111111 where 11'1cthe limestone1E.'11:.'<1.111L- :1L'L‘1111111111tL'L1accumulated duf'ngduring the Pleistocene1’1L‘1L111L'a period.116111111111In the111: Wajir\‘111111‘ Bor-RibaBur-R1111 50411011section the111: limestones1‘111US111H‘N‘ 111‘of 1111‘the Wajir\\"1i:‘1‘ 11m.beds :12.are thin111111 in “11:113.;places and 10L?“111.‘locally (1'11;the 1151:1111gypsum overlying11\L‘1'1}111g 211L111them \L11‘1L11111LNsometimes accmseemingly1121;1'1:\1\rests .111on the 111111“.Jurassic .L‘Li11‘1tmssediments anda: it :11‘1Laappears 111'A1.that “.31:the 111‘1L‘\:1.111L‘xlimestones .1are;‘ evenL1-L11 11756711absent .‘11in places. Gypsi- ferous:c1‘ 1% depositsk1Lp‘\ 1x are11'.- found11.11‘11 3111-13along a11 211111:zone stretchings11'L'1L‘1‘111g 1:'.1:11from ElE1 Reh19.611111in 1‘-the ~.:11111_-1.'.south-west,L‘xi. through:nmugh Rama Agun.Agon, EI. ‘Tuli,:. 1\1’1111'111Khorof Atat,5.1.11. \‘111111'Wajir Bor,Bur. R11,Riba, .111L1and BalballaB111l‘;11 to1D1111:11‘,1;1Duduma

Aad311d in111 1116the cm:east 1...»(see Fig.1- 11'. 1).11. ‘111:The - gypsiferous.M11L‘1111 x1111:zone 111.1'L‘L1~.'\1increases in:1 11width.1111 1.11.1116towards “-‘1L'the A‘aa‘.east which11111.11 is largely due' to the«E11111;11'.‘.1111.1111111.slight unconformity between the gypsum and overlying grey soils and to a lesser extent to a thickening of the gypsum at the expense of limestone in that direction.

r~~ ﬁx 23“.3

The gypsum rarely appears on the surface, but its presence is usually detecieddetected by light grey dusty soils containing numerous calcareous and gypsiferous nodules with some water—wornwater-worn quartzitic pebbles. The lower parts of the gypsum are exposed in the wells of El Reh where it is seen as chalky gypsite, but at El '1Tuli,uli, higher in the succes—succession.sion, it is fifinelynely banded in alternating indurated and chalky lan'tinations.laminations, with some massive crystalline bands. Single gypsum crystals.crystals, up to one inch in length, are found scattered on the surface. A curious feature of many of the gypsit’erousgypsiferous occurrences is the presence of the water—wornwater-worn quartzitic pebbles on the surf’ce,surface, a .I‘eaturefeature which was also noticed at lilelloJilello where a lens of gypsum is interbedded in the grey soils over—overlying the Wajir oeds.beds. Specimen 31;".3.31/3, an example of gypsltcgypsite collected at ElEI Tull.Tuli, is buff-colouredbull—coloured and bandedhanded with hard induratedindur‘ated bands alternat‘ngalternating with powdery white lay-“rslayers which et'l‘ervcsceeffervesce with dilute hydrochloric acid. The banded appearance seems to be a second—secondary feature with the induratediudurated bands of gypsum forming at the expense olof the soft g'-'_psite.gorpsite. theThe thin section exhibits a line—grainedfine-grained aggregate of.of gypsum euhedra in random orientation.orientation, together with random sub—roundedsub-rounded clastic grains of quartz,quartz. Banding is elleffectedcted by strips. s of fifibrousbrous gypsum with the fifibresbres elongated across the bands. Carbonate is present as dense tine—grainedfine-grained patches and the thin section contains a rounded pellet of dense brownish carbonate.carbonate, 6 mm,mm. across.across, which encloses rounded quartz.quartz grains and has irregular veins of clear finely crycrystallinelline calcite aassociatedacaated with.with black,black. probably manganiferous,trianganiferous. material. Gypsum sometimes occurs within the veins enclsedenclosed by the calcite, while the gypsum surrounding the pellet is fifibrousbrous pet'pcndicperpendicular - to its periphery. theThe crystalline rock gypsum consists of an aggregate of fifinene and coarse selenite.selenite, sometimes pink in colour.colour, and with random orientation. 'l'heThe absc‘absence:e of carbonate can be detected by the lackiack of cil‘ervcscenceeffervescence with dilute hydrochloric acid. Parkinson (1920.(1920, p. 14)1—1) mentioned that Salkeld had noted in descending order gvp:gypsum,n. clay.clay, black sulphurous sand.sand, stones and hard white sand at El Tuli. 'I'heThe thickncthicknesss olof the gypsum is indicated in unsatisfactory logs of bore-holesbore—holes drilled during the.the war at i-itEl ‘l'uli.Tuli, Wajir\.-‘v"ajir Bornor and Riba. The probable thickness orof the gypsum and underlying limestone at El tubTuli is indicated as 30 ft.._ft., but it increases to 3536 to 44 ft.it. at ‘v-VajirWajir Bot:Bor and Riba respectively. As these bore—holesbore-holes were not drilled through the full thickness of thethe gypsum.gypsum, itit. is possible that it may be as much as twice as thick as thethe

bore—holesbore-holes seem to indicate. 1

T'heThe Wajir Beds dip to the south a.at an angle only slslightlyphtly- more than the slope of the surface of the country south of Wajir.Wajir, but the indistinct bedding displayed in the gypsum of.of the wells at Riba o'tenoften has a slight easterly dip. Irregular,irregular. usually vertical,vertical. scleniteselenite veins traverse the gypsum and usually strike N.N.E.,N..\-'.E.., but the selenite veins in one of the wells form a circle on the side of the well. ItIt may be noted that the esiexistingting wells have been dug along zones ot‘of selenitcselenite veining. Undulations in the gypsum were noticed in wells at Riba, but the direction of the axes was indeterminahle.indeterminable. Similar undulations also occur in the limestones south—eastsouth-east of Wajir and are rereflectedﬂected by low surface limestone ridges, striking north—southnorth-south and rising 10If} to 20 ft. above the general level of the surface. Bestovv'Bestow (195.4.(1954, pp.pp, 4‘54-5 and 11—12)11-12) also postulates the existence of an anticlinal ridge striking N.W.—S.E.N.W.-S.E. through E]El Murille with a corresponding trough on the northern side.side, and a sharp monoclinemonoeline of.of similar strike at Ciauuri.Ganuri, outside the Wajir area. The gypsum at El Reh may well occur as a lens in the limestone.limestone, but it is possible I that it is a pocket of gypsum preserved in a synelinalsynclinal fold formed during the com—com- I paction of the Wajir Beds. l~ paction of the Wajir Beds. Early travellers through El Wak nearly always commented on the numerous circular depressions in the area, the largest.largest being about a quarter of a mile across and perhaps 30 ft. deep. theThe depressions are usually lined by surface limestone when occurring on limestones and rarely serve as water reservoirs. The origin of the depres—depres-

r r

I ~ II " " 24

sions is obscure as they show no preference for certain types of rock,rock. they occur singly or in groups and display no pattern in their distribution. Twenhofel (1950,[195.0, p. 59)5.9} describes similar depressions formed in deserts by deflationdeﬂation in unexpected places,places. the lower limit of aeolian erosion being the level of the water-table.water—table. If the depressions in the Wajir area formed in this way, they may indicate the drop in the water-tablewater—table level since the time of their formation. The lithology and variability of the lower part of the Wajir Beds suggest valley—flatvalley-flat sedimentation which was succeeded by laeustrinelacustrine conditions when the channels were choked, giving rise to the formation of the limestoncs.limestones. 'l'heThe limestones were formed over aa widespread area to the north and west.west, but the thinning of thethe limestoneslimestones south—south- east of Wajir and the deposition of gypsum diachronous with limestone points to a shallowing of.of the lake andand desiccation in thatthat direction, where swampyswampy conditions probably existed. The post—Cretaceouspost-Cretaceous sedimentssediments overlying the Basement System has never beenbeen pierced in the present.present area but many of the pilot wells put down by the Public Works Department further north encountered rock belonging toto the Basement System at vary—varying depthsdepths and showingshowing thethe Wajir Beds thinning out in that direction, where theythey were deposited on an uneven surface (Bestow.(Bestow, 1.9541.1954). Deep bore-holesbore—holes south-west of Wajir at Ndeges Nest and Muddo Gashi revealed clays and sandstones,sandstones. while to the north pilot wells and bore—holesbore-holes asas farfar asas Buna yieldedyielded interbedded limestones. The Merti beds of the southern part of Northern Province as well as the Wajir Beds and the deposits at Golana Gof and Muddo Gashi were referred by Dixey 0.948.(1948, p. 9i9) to thethe Tertiary, an age adhered toto by Ayers [1952.(1952, p. 15.).15). This dating followed the discovery that some of the beds are entrenched by valleys in which certain of the lower terraces yield Middle Pleistocene implements. Beds of possible Miocene age in the north Kitui district .are.are described by Dodson {1.955.(1955, p.p, 20) while clays and sands underlying the Lower Nyambeni basalts dated as Lower Pleistocene (Mason.(Mason, 1955, p. a}6) were encountered in bore—bolebore-hole No,No. C136, situated half—wayhalf-way between Garba Tula and .[siolo.Isiolo. .ltIt is therefore assumed that beds of Miocene age may occur buried under the Wajir beds. Dixey (E948.(1948, p. 10) also ascribed a Tertiary age to the ElEI Wak Beds which are without doubt the northern extension of the limestones and gypsum olof the Wajir Beds. Recent mapping, however,however. has disclosed that these beds occur in depressions in the end—Tertiaryend-Tertiary peneplain which dates them as Pleistocene and an Upper Pleistocene age was tentatively put forward (Baker(Baker andand Saggersun,Saggerson, 1958..1958, p.p. 34; Joubert.Joubert, 1960.1960, p. 48}.48). The post—'l'ertiarypost-Tertiary ageage is substantiated in the Riba areaarea where smallsmall ferruginous eon—con- eretions,cretions, which normally typify the end—"l'ertiaryend-Tertiary surface.surface, were found on top of the mounds of the material derived from wells which penetrated the gypsum of the Wajir Beds. When the sequence of the post—Tertiarypost-Tertiary sediments of the Wajir area is compared with that of the sediments occurring along the DauaDana river, on the northern border of Kenya, it is reasonable to correlate the limestones and gypsum of the Wajir Beds with Shangalla Limestones and the gypsum of the Gingo area,area. which are dated as Kamasian {Joubcrn(Joubert, 1960, p. 46). The logs of the pilot wells north-north-westnorth—north—west of WajirWajiT show that the limestones of.of the Wajir Beds,Beds. although variable in thickness,thickness. are almost continuous and that the lower part either contains pebbles or is at least highly arenaceous, or that the limestone is underlain by pebbly clays.clays, sands or sandstones (Bestow, 1954, pp. 40-46}.40-46). Small quartz pebbles are also recorded as occurring in a grey calcareous loam underlying the limestone at Sideh in the Wajir well area (Bestow,(Bestow. op. dt.,cit, p. 17). Conglomerates and grits occurOccur at the base of the ShangaliaShangalla limestones,limestones. and as they were taken to represent the onset of the Kamasian Pluviall’luvial in the Mandera area=area, it may follow that the sandstones underlying the limestoneslimes-tones in the Wajir well area.area, represent the firstﬁrst inter-pluvial,inter~pluvial. i.e. the upper part of the Lower Pleistocene. The sand—sandstones are often ferruginous (Bestow, op. cit.cit., p. 11).ll).

~. ---,

ﬂ

25'Jl

During the present survey fossils were collected in the red soil and nodular kunkar on top of the Wajir\Vajir Beds limestones. They were identifiedidentiﬁed as the modern terrestial gastropod AchatinaAchmimt fulicaftlfica hamilleiimmiffei (Pet.),(Pet). which is of no diagnostic value. Parkinson (1920,(1920. p. 12[2 and 17)[7) recorded BythiniaErr/tr‘nin and PlanorbisFlam-whit spp. from the Wajir Beds and many ~< other fossils collected in the Cainozoic sediments to the north-west and south—westsouth-west of the present area. Mr. R. Bullen Newton,Newton. who identified these fossils,fossils. tentatively correlated the sediments with PliocencePliocenee lake beds in French Somaliland. 'lheThe fossils found have an age range from Miocene to Recent,Recent. but so far as present knowledge goes,goes. the limestone and calcareous deposits which yielded them were not deposited in pre-Pleistocene times.

(b)lb) FERRUGINOUSFtl{l

.,, I r-

The conglomerates are always(itways encounteredenetItmt-ered near to,to. or where the MansaMarisa Guda(judo Formation is exp-eexpectedetetl and thereforethereitore it is reasonablere astI—ial to conclude that the MensaMansa (judoGuda Formation was exposed in the area mapped up to the end of the Kamasian plttvial,pluvial, after which the conglomeraticetIng'ttInItIratie sandstone formed in .Iitti.situ, eeneealingconcealing the MansaManse GttdaGuda Formation.Ft‘trtnation.

(c)t‘tIi THIN LAMINATEDl..\.\tt.\\tt.D LIMESTONESl.l.‘~”.5l‘;}.\l.‘§ Limestoneslimestones merlyingoverlying the ferruginoust'eetIgIntIus sandstones are patchilypatehilytdistributed'lis. I'ibttted on the flanks of the lowl-eII hillshi"s formedterriﬁed by thetriie Jurassic_l.1rassie limestones.liitIesttIaes. Itl: is thoughtthottglt thatt .at most of the surface limestoneiinIesttI :Ie patches:Izitehes IItIitlInorth \Ii:of RibaR: btt t‘e‘CllFl'ii'ltcjoccurring on‘III the .ltLre-tssieJurassic limestonesliniestones represent pockets of limestonelittlestt nI-I deposited duringInII the KanjeranKanieran stage tIfof the Pleistocene.Pleistotene. Patches . tIiof itle'nlsuchI limestone.eI ‘.\l“llC still exist in the Wajir Bor,Ber. RibaRiba. and'Id DudumaDudttnIa Aad areas.areas, \yhiehwhich sugtje~tssuggests that depositdepositionIon wasw 15 III»widespread:tII pretttl during this period.perked. Two miles south ot‘of Wajir‘.'I'tt}_ir BorBot" on methe BarderaBard-era road,rtttttl. military:IIilI tar). excavationseuttyutinns in the limestone indicate Ll.a thickness of -.-.tat least 6(I feet,'ee:. but at Riba,Ribtt. where these rocksroeits havehaxe been entirely altered to surface limestone,iimestone. only about L2 feet occuroeeur overlyingoxerlying the gysum.gysunt. Therelhere is again an increaseincrease: in thicknessthiekitess in'n the DudumaDtttlzirIa AadAnd area,are but as exposuresexpenures are poor and the limestoneslimes-tones lie directlydireetly onen litter-toneslimestones ofoi the Wajir‘u‘saiI: beds.beds, the ewetexact thiekitessthickness isIs indeterminate. An_-I\:I attempt was made:I .iLit.‘ to map these limestoneslinestottes as a separate unit,unit. butIt the patchypatent distribution and the Zitltelegit'allithological similarity to the.the li:II.esI.tItI.eslimestones ot‘of the \‘IajirWajir ThisBeds as well as the suhsequentsubsequent alterationtiltet'tttItIn to surface limestone of both horizons made distinction in nearly allail caseseases impossible.impossible SpecimencipCL‘IH‘lCl’l 3i31/60,(IL) etI.collectedIleetetl 23 miles north of.Il‘ KltoroiKhorof .-'\t‘.t'..Atat, is typiealtypical of the laminated limestonesiimestones in being finelyltnely bandedhanded andt-tnd fissiletissile along the bedding planes. TheThe tnfe‘rosetIJ‘ICmicroscope revealsreyeafs a brownish matrix eonsstlngconsisting ot'of fine-grainedtine—grained earhonatecarbonate grains e._I'.I‘.tI:Ii:II_,Icontaining numerous rounded to angular detrital quartz and saleitecalcite grains arranged in bands along the bedding. Some of the detrital CLLiL‘l‘tCcalcite tIeetxrsoccurs (isas erysialscrystals showingII. min” toriginalIr zin al iatesfaces but

rounded a.aggregatesIII: gregates are the predominant i‘L‘l-lTl.form. The matrhmatrix is iron-stamediron-stained in patches.patches,

while 7it‘zircon,:3 . rutilet‘utile and hematite eontpletecomplete the etIn'tptIsititIncomposition of the roek.rock. At DudumaDttdunta AndAad the limestonelfmesttIne etIntztinscontains in its upper part many water-wornII.ateiI—\I.0t':t pebbles eei:derivedIiyed from the Jurassic litt'testttnes.limestones, the pebbles in conjunction with the arenaeeottsarenaceous eharaetercharacter otof the laminated limestones.limestones, showing that tittviatilefluviatile eonditionsconditions played a major role during deposition. The lintestt'Irteslimestones DIEL‘Tliuoverlie the gypsum oiof thethe WaiirWajir Beds 11‘.at RibtliRiba, thethe lil'I'te‘wUH'lL’Rlimestones Ul-of tltethe \‘vajirWajir Beds :ttat DudumaDtttlttma .\udAad and the .lttrttssieJurassic limestones north Ui‘of lx'htIrtIfKhorof .-‘x‘.Atat.t. 'l'htts.Thus, they titerstepoverstep the ferruginous sandstones and the \‘I'ttjirWajir Beds onto thethe Jurassic limestones.liittestones. This inyelyedinvolved remoyalremoval of at least parts of the ferrtigit‘ieusferruginous sandstones primprior to the deposition of the laminatedi.tntit‘:.t'.ed limestones,liltslﬂflL‘s. whichwhieh are. e therefore ttne..t:tt'nrinableunconformable on the underlying sediments. When\\ hen the age suggestedsuggeste' forttIr the underlyingtrade :‘yl'ing.sedimentssed nICnts is considered,et- nsi tiered. i:it followst‘oilows that the laminated limestones were probably deposIteddeposited during the onset of the Kanjeran pluvialplttyial stage.st age The limestones may be eorrelatedcorrelated with the ealeareouscalcareous silts.silts, ntarlsmarls and eonglomconglomeratescrates of that age inIn the DauaDana valley,Ittlley. whichwhieh yielded an artifact of thethe KornbevxaKombewa t.- techniqueteehniquet(Joubert,t..loubert ]1%).960, p. art.47).

tt/I(d) GREY AND Bum;BLACK GRITTYGRITIY SOILS South of the area oeeupiedoccupied by the WajfrWajir Beds,Beds. large tracts of country are covered mainly by unconsolidated clay—houndclay-bound sands. TheThI etIltIttrcolour of(Ii these soils is generally grey.grey, but is sometimes brownishbrownis.h greygreI and in the low-lyinglow— lyingr parts.parts, whichwhieh become water-loggedwater—logged in the short wet spe.ls.spells, the colour tends to dIrhdark grey or blaek.black. The soils are composed oiof approximately 75 per eentcent of granules.granules, consisting of coarse and medium quart/tinequartzitic sand.sand, with 25 per eentcent of grey clay which etl‘erveseeseffervesces

~ --=---.~ ---:- -' --d

withith dilute hydrochloric acid. Greater amounts of carbonate are evident in patches where the soilsuit becomes nearly white in colour,colour. with1-.ith a marked absence of trees.treea. The calcareous patchespatehes are evident on the aerial photographs and

Berl "1} r and JJ'ilello.leilo. When“' hen the wilxsoils a1L-are hrourtiahbrownish grey they are e\iL'!eevidently11tl3-' lessiCR.\ caleareouscalcareous and also ie5

MgO " . . . 2.872.5T

CaDC210 "...... 3.56 Total AlkalisAlkalix as NapN211.) ...... 1.391.3%) L085Loss on ignition tles's(less (OCO) t , ...... , 16.11tall CO2(VT) ...... , 1.391.351 S0380: ...... nilt'Lil

99.14L1,): #

Analyst,.41111'.-"j.'.13. J..I. Furst.Furxt. A bore-holeborehole at Dif,Dil. on the border 353.1 miles1113i 9 southxouth ofet‘ the presentpresent area,area shows\ho'o< that the grey soils\U‘iiﬁ attain a thickness ofLil at least 3603M] feetfeel there and that the composition,LL.11111L1s1-L1:.1 excepte\ee}1t for minor variations\lli’i'L'L'LitJIiS in the amount of grit and carbonate asax. nodules,ntttl‘dirx. is:'~. fairly1.1i:'l'-. uniform. The underlyingunde 1g brown ferruginousfer: it‘tJLiS sands,aands. whichwrtieh are micaceousnucaeeeua here,hr" occurL1.'L':.11' between 3403-10 and 3803H“ feetlee“. below the surface,Litee. which\\ hieh indicatesillCitCl'tiC\ a slopesiope of thet} ' base ofot' the greygre3' soils and underlying11:1Lle1'l3in1:1 laminatedl'L11111'nLtted limestonel1n1ex1L1ne coincidingcoineiLiing with‘L\i’.h the dipdin of'ol the Wajir\'\ai::‘ 11\ Beds,Bed». whichtxhieh is3.11 14 feet per mile to the S.S.E.LLSE. (1'35:L1l|1neCrystalline gypsumg3phun1 mandatedassociated with“1‘51 water-“ate:- wornLL-orn quartziticquart/hie pebblesPchi‘iLN was11:1.» encountered at.1: :1a dep:hdepth oi"of 180lh‘tt l'eetfeet in the bore—hole.bore-hole, while33hile the grit in the claye’a3' sometimes attains pebble size. Gritty(iritt3 calcareous claysL'l"3\ encounterede:1-'L1unte1'eLl between 240140 and 340140 feetteet belowhei UVL the surface\tulaee probablymohahl‘rrrepresentepre

ItIt is thought that ththe O grey3: _L soils were deposited in a lioudflood plain environmente113'i1'L111L11ent

during the Kanjeran pluvialplmizl"“ stagetage andan (I that the depositiondeposit 1011 followed L'unfL.conformably1 :1. [1&1l on1.111 the laminated limestones.1.111estone3. The'i he gre3grey e'LtlLareothcalcareous gritsaritx and gypsiteg_1p\ite in the DauaDatia valleytall-11. '\-occurring"-LL‘L. . ' below the 3H30 m.111. terrace (Joubert,' t‘ ert. 1960,E‘JhH. p. 47)4?] were probablyprobahl3' eon-.e111po::u3contemporary withnith the grey soils of the Wajir District. - (e){111 RED-BROWNRE!)— B: 113\'\ ANDMt) YELLOWISHYmumtsu BROWNRat:'1\\\ CLAYS(1 W115 Dixey (1948,([948. p. 10)1111 mentions old native-dugnative—dug tankstank; in dark brownb11131 [1 claye133 withith gypsumg3 11511111 nodules at Gherille and Dif.Bit. These'1 hese claysdays are of great importance to the Somalis becausebee-Luise 11ftl1eirof their intpermeahilit}impermeability to water,water. pans11am dug in the claye733 containing water for long periodsperiadq during and even after,after. the rainytat-111' seasons. Such water-pansvial-e1 pans nectiroccur at AbakAbuk Fin,Fin. Akal Ar,Ar. WelWei Ade and Ibrahim Uri. At Aka]Akal .-’\.rAr and \\"elWel ."\deAde the claw;clays are alightslightlyi1. LljiterehdifferentLt liomfrom els'eelsewhere1\here in being red in eolourcolour with caleareocalcareous:9 nodules,noduiei. while at AbakAha}; F.'Fin11 ththeye'_-. aimalso contain water-wornwater—worn pebbles,pebbles originally derived from the MamaMansa Li.1LaGuda Formation. The clays are ext:extremely

...!

[ ......

linefine and become very hard when dry. From their distribution it i5is seen that they are associated with the drainage system and they are therefore thought to basehave been formed by a process of illuviation (Robinson.(Robinson, 1932,1932. p. 145). At.-\t Ibrahim Uri,Uri. leaching was apparently restricted owing to excess of evaporation over rainfall which inhibited the removal of siliclesilicic acid. Thehe clays are usually better developed along the western sides of the drainage ehannels.channels, probably lndieatingindicating an easterly migration of the drainage system.system, elongated remnants of red—brownred-brown clays marl-tingmarking the position of old channels. The existeneeexistence of these clays suggests a period when the rainfall exceeded present precipitation.precipitation, and from their stratigraphic position it may be deduced that they are post-[\‘liddlepost-Middle Pleistocene in age. (fl(j) RFDRED .tsDANDGREY SonsSOILS On the JurasJurassicfie lirnestt'ineslimestones fifinene dusty soils occuroee which can be divided into red mature soils mainly occurring in the elevated areas and foéloylingfollowing the softer limestone beds, and younger grey soils «.leeurringoccurring in the valleys and associatedassoeiated with\\ith surface lime—limestone. Robinson (1932.(1932, pp. 427-429) reeognixesrecognizes lWOtwo d5distincttinet groups of soils that form on limestones-alimestones-- a grey; C1.” group ehurueterl/edcharacterized by excess of calcium carbonate and a red leached group expeetedexpected in upland r-regions.on~. The'l he red soils in the Wajir“hilt area gluegive expression to:o the strike of the Jurassic line-stone;limestones where they t'oiloxxfollow sot'tersofter horizons,horizons. or occur along lines otof sll'Lle‘IUI'dlstructural weakness'vvealtnes's \yhiiewhile the grey soils occur along present drainage ehannels.channels.

(g)lg) VV“ ALLEY.o LE Y SortSOILSs River soils in the:he area are dependent on the type of soil being traversed by the drainage.d 'nage. AlluvialAlluvzal deposits are non-existent,non—existent. and most of the soils have been producedproduce by the removal of certain of the components of other soilsSoils or by illuviation. The red sandy soils either have some of the sand removed or are enriched in the clayey component and very often contain nodules of kunkar.kunlsar. The water-panswater—pans in such areas receive much water during the rainy season.season, but it is lost underground soon afterwards. Where drainage channels cross areas of grey soil.soil, the colour of the soil becomes darker and at Ibrahim UriLTri many pebbles derived from the MarisaMansa Guda Formationi-l'irmatlon occur scattered.scattered, or in small sheets.sheets, along the river channel.

V-GEOLOGICALV—GEOLOG ICAL mSTORYHISTORY

The lithology,lithology. structure and stratigraphicalstrat'graphieal sequencesequenee of thethe sedimentsSL‘LllTl'lL‘l'lls of the Wajir\‘v':-.ji:' area permit the following interpretation ofol‘ their depositional history. Down-warpingDonn—naming of the Kenya coast was initiated towards the close of the PalaeozoicPalaeoroie (Caswell.(Caswell, 1953.1953, p. 50:50; Thompson,Thompson. 1956,1956. p. 42142) and it is therefore likely that the transgressiontransnression of the sea into a gulfgull“ in north-easternnorth—eastern Kenya took place at approximately thethe .sameie time. ItIt is suggested by 'l'hon'ipsonThompson and Dodson (Tit-trill.(1960, p. :4)34) that the MansaMarisa Guda Formationl-'orn'.ation “aswas deposited as a delta into this sea and that the materialrituterlal was derived froml‘rom an area that was rapidly being denuded under arid conditions. Recurrence of dmm—uarpingdown-warping followedl'ollovved inin Lower Jurassic.lurassie times and allowed the sea to overlap onto the .‘ylansaMansa GildaGuda Formation and spread to the north.north, the tilting being continued up to Middle JurassleJurassic times after “hiehwhich the sea gradually regressed from the Wajir\Vajir area as a result of infillingintililng by sedimentssediments. The nature of the DauaDalia Limestone Series suggests deposition in a shallow epieontinentalepicontinental sea where intermittent changes of sect—levelsea-level gave rise to thick-bedded grey limestones alternating with oolitic and cross—lsetldedcross-bedded silty limestones,limes-tones. and sometimesson'letin'tes eveneyen intra- formational eonglon'ierates.conglomerates. During the deposition of the upper parts of thethe Bur Mayo Limestones.Limestones, the oscillations were“ere of small magnitude and currents active.active, giving rise to thinly bedded fragmental limestones.

- ... ~- - - .....'"-"" ;::;::.i

The faultsfauits that transect the Jurassic limestones are parallel to faults of Cretaceous age along the HegaJluHegalu hills in the Mandera area (Joubert,(Jooberl. 1960,“960. p. 51).5!]. Itit is likely that the faulting in the Wajir area took placeplace during the same period. The faulting probably initiatedinitiated extensive erosion which continued during the lower Tertiary times and resulted in the fort‘nationformation of a wide and deep valley west and south of the Mesozoic sediments. There is no evidence for a structural origin of this depression and it is therefore thought that it is the consequence of denudation and scouring of the Basement System by surface wash.\\ ash. During the Miocene Kenya experienced sedimentation at many localities and it is almost certain that at that time the Wajir depression receivedreceiyed some sediments,sediments. of which much must have been removed again during the uplift of Pliocene times (Thompson 1956,I956. p. 45).45,. Subsequently the end-Tertiaryend—Tertiary peneplainpenepiain bevelled the sediments of Mesozoic age.ace. Slow entrance of sediments into the depression occurred during the firstfirst pluvialphivial phase of the Pleistocene,Pleistocene. when clay-boundclay—bound sands with lenses of sands and pebbles were deposited along a wide valley-flat.valley—fiat. The red sandstones of the Wajir area are ta‘xentaken to represent the following inter-pluvialinter-phivial phase,phase. while the arenaceous and pebblypebbiy nature of the base atof the tiniest-oreslimestones ot‘of the Wajir'y‘s’ajir Beds may indicate the sudden onset of Vigorousvigorous KamasianKantasian pltn-‘ialpluvial conditions. During the latter period widespread shelitmshallow lakes formed,for: ted. in which impure lintcstoneslimestones were deposited. DesiecationDesiccation at the close of this phase gave rise to the gypsifcrousgypsiferous deposits to the south and east of Wajir.Wajir, and eventually these conditions gave way to sob—aerialsub-aerial erosion on an area of low relief which resulted in the formation of the ferruginous sands. At this time the Mansa GottaGuda Formation was still exposed or close to the surface and the deep Weatheringweathering of its conglomerates rel-casedreleased pebbles,pebbles. which were then includecincluded almost in rimsitu in the ferruginousferrnginous sand. Shallow sheets of.of water againag:;in formed over the area during the Kanjeran PluvialPluyiai phase,phase. but their outlines did not conform to the s:shapewe of the lakcslakes of the previous phase.phase. This feature can be ascribed either to the pl'L‘L‘LLt‘lil'lgpreceeding erosional stage or to slight tilting prior to the deposition of the laminated limestones. After the firstfirst intense spasm,spasm. the Kanjeran pluvial phase reverted to milder valley—valley-flatflat sedimentation of clay-bound sand.sand, with lenses of limestone and gypsum forming in small pools of “water.filler. Since Middle Pleistocene times erosional forces have carved the Wajir area to its present configuration. .1 configuration. I II VI-MINERAL\"l—MINERAL DEPOSITS " 1.'1. Oil The Jurassic sediments of north-easternnorth—eastern Kenya constitute a small portion of a sedimentary basin of vastvast areal proportions,proportions. extending into Ethiopia and the Somalias.Somalia-‘1. The basin as a whole must be considered inin the search for oil in this part of the world.world, and information on the rocks of the Wajir area is of importance in completing the picture. The palaeontology of the DidimtuDidimto Beds indicatesindicates a marine linklink withnith MadagascarMadagasear I during Toarcian times, a connexion whichehich was subsequently severed if the scanty fossil I data is to be relied on. As previouslyprcxiously mentioned,mentioned. the sea transgressed to the north with rise in sea-levelsea—level since the Bathonian and it is therefore likely that at a certain stage in the sedimentation,sedimentation. the marine gulfgolf inin north-eastern Kenya was somewhat restrictedrestricted and favourablefavourable conditions forfor thethe formation of oil existed. The great thickness of marine limestonesliroestones in the Jurassic succession presentspresent. no scarcity of source-rockssource—rocks and suitable host-rocks exist in porousporous horizonshori 0:15 such as are represented by specimen 31/4531 '45 from the present area (p.(1). 15),i5]. or inin highly jointed lime-lime— stones. EffectiveI-ill‘ectite seals would bebe formedtorn-ted by the many dense argillaceous limestonelimestone horizons.

... I' r---

30U.) 0

The faulting of the Jurassic limestoneslimestones mayma} also provide structuralStructural oil-traps,oil—traps. as the faultsfaults probably extend much further to the north-eastnorth—east inin an area of no exposures,exposures. where folding may also bebe of greater significancesigniﬁcance thanthan in thethe Wajir\\-"a_iir area.

2. Building Materials Although of an inferiorinferior quality,quality. all material for building purposespurposes in Wajir\Vajir is at present derived from the limestones ol‘of the Wajir Beds. The softness and fissility[is '11 of the limestones,limes-tones. which facilitate the grinding and the cutting of dimension stone,stone. as well as the proximity to Wajir‘.\":1j:r render it the Cheapestcheapest source of building material.111:11e1‘ial. The .lJurassicur:1ssic limestones.limestones, which can yield better quality dimension stone and crushed stone for concrete aggregates and road metal,[ll-CELL “illwill hardly be quarried until such time as the area is developed,de‘ -eloped. when improvedi111pro1'ed buildings and betterbezter roads are required. All\ll thethe components for natu:naturalal and Portland cement are within11i‘ 'I1 C311}easy reach oiof Wajir,V1 ajir. 33.111but the reremotenessrooteness of the area makes the likelihood of production improbable. (31-11mmGypsum and lime,lime. sources ol‘of which are abundant in the areaarea, can hebe useusedd for many purposes.purposes, but as they do not oL'curoccur in the 1icinit1.vicinity of de1-e'1o11cddeveloped commoncommunities,1itieLs eancan only serve as structural materials. 3.. Water“Ener- The'1 1e most vital1ital and immediate problem of.1!‘ the Wajir‘1\'aj"r District is water-supply11 aterenipph and therefore it has receivedrLLe: 1 d 11muchunit aattention' :I: in the past. The firstI]. ‘. hydrographiclrographte surveys'n 1 ofol‘ the Northern. orlhe: I1 ProvincePIo1-i11L'e was11. is carried out byb1 Dixeyl)i\e_1' (1944),119441 whoseethos: recommendationsl‘e‘L‘LtrtittlL‘tillltit‘ts .7. 7..“ . are now being implemented.irtiplen1e‘1‘ed. SinceSinee then BestowHeston. tl‘t‘oJ(1953) has LcarriedIrrfed out aL. comprehensiveL-.Il eliciwﬂt L1 hydrologicalt.IL1lL1g'-:al surveystII1L1-11i'hwith referencerL to the Wajir\\';tjir District in:11 particular,particular. and manyman} of hisl1:\ findingsrind ions are incorporated in this-.’.-s chapter. The 1111]}only permanent water Itin the area '1is loundfound in the 11ellswells in the immediateimmediat-L vicinity L11of Wajir,Wa1ir. 11'whereL" .the'1l1L‘ surface has now:..1.u been Llerudeddenuded L‘lof pasture311911;? 1111.and it has become necessary withmm the increase in inestoc‘s.livestock, to locate Haterwater sLIuicessources in areas of good grazing. Besto“Bestow top(op. cit.,151.. appendix F)H foundiotgnd bit841 wells\‘-.Cils in :1a radiusruckus ofo1 about 91.1 miles- 1' around Wajir,\-\-"aj.ir. of 11hi-whichh 3L'Il301 Werewere in use at the time of his investigation.isLIgatILI‘ The 11wells5' usually vary1:11‘1' in depth from 2523 to it]50 feettee! and taree from[root 3—124 to 32 inches.:1ches :tossacross, 1hthough11-;Ieh they often hellbell out in depth. Bestow disemereddiscovered two11111 11:1ter11ble.i:1water-tables in the “'1Wajir. Beds,ds. which1.1hich in the pilot well\1ell 2 miles north of the tourishIp.township, oect1ratL11hsoccur at hedepths 1.11of 51.150 and 71' feet respectively.rcspecti1-el1. Thethe upper aouiler.11l1i.:l1aquifer, which is sometimes as thiel.thick as :125 teet.feet, is.is usually11-11; . a uniform lighbcclomedlight-coloured saI‘.sandy clayClay buthut varies\“Ltt'IL‘S n-.LIehmuch laterally both in lithologylEIhL-loe‘t and thickness and affectsatl‘ects the yield1 d 111of wells,11el. 51 11sas 11eliwell LIsas the qualitydual of the water, from one well group to another and sometimes between 1-1wellsills of the same group.rroup. The yield1icld of the wells11el:'s 1:11':esvaries fromlrom negligiblenee "I’bler to111 inIn eVeessexcess ofol’ 2,500..‘ I gallons per11st day.Lia} Thelhe water always211111115 containseontaIns a large proportionpropor on of mineralrnInL-ral salts.salts, .19as is \L‘L‘llseen in Table III. BestowBcs'o“ recordsteeords that the water-table11.11er‘table is droppingd:-.1pp.ng from 2 to —‘:4 inches annually112111.111}. .1:1.iand summarizessutnntarr/es the C1evidenceidence to prove this on page 33 of his report,report. but remarksremark» on page1 16H1 that wellswelt. havinghaLing a high yield cannot behe deepenedLleLp-LnLLl far1:11 belowbelou the water-table.11;11e1‘—ta'rilc. He postulates a southerly seepage to account for part11:11.1 ofo! the lossloss. ofot water.“1116?. It is well-known1.1 ellelL'no-Lx :1 that the Somalis,Somalis. who entered the area around 1906,lUllh. have not deepened an}any 111‘of the wells,11etls and as a fewten otof the wells11L lls have more thanth' :11 5 feet of water in them,then-t. the drop in the water-tablewater—table cannot be as great as calculated by11J Bestow,Bestou. or the wells would\xoLiid all have failed byh} now.11011. It is also true that the11: populationnor.“ 1:1 and the number 01of livestocklit eto: l\' have increased considerably since the British occupationoccupa . on with a consequent higher drain on the water-supply.water—supply. Other wells in the area have beenhe ‘I1 dug in the gypsiferousL11psiferous deposits of the Wajir\‘."a_iir Beds. Such wells are found at EIEl Reh,h. Rama Agon,Agon. Khorof Sharif,Shard. EIEl Tuli,Tuli. KhorofKhomf Atat,Atat. KhorofKhoret Higlithi,Higlithi. Wajir Bor,Bor. Riba and Balballa.Bazballa. Thesethese wellsweds are said to behe perennial but during the drydr} season inin the courseLourse ofLI' the surveysome} it was found that they were either completely drydr} or had polluted water11 ater insufficientinst; forA even. a s:1:;1llsmall numbernum. of stock.szock. Sincee thethe Somalis invaded the area,area. many111.2111} ot'of the wells have beentact-:1 '_Ll_o11'e-;;allowed to

~ ~ 'l'.a\l‘}|..l'.TABLE IIIIll Chemical('lwmiml Analyses ofnl' WatersWniers from thelllC WajirWujir WellsWel IH

Number.\' u m be r I El"Ll“ l'll‘of H Bey" Well"\VCIH Makoror"Mu lxm'nr'l‘ Wichir"W iuhi r* Anissa"Amsm * Kumbe"K Um luv" Raifeti"Rail-ell" MurilleMurillo EIIll Nur"NUT"F \‘l-"uglmll:t""Waghella" Bangal"Hang-3H =-‘- I School.St'llunW Wajir\\' ;i_ii!' EI Bey" “1).. Well\‘l-"L'll .. No.1N0. | "D" No.Nu. 464n No.2]NU. 3| No.\(J. 5355 No.3\u. .l No.\u. 14 No.2{\n. l No.Nu. 25 No.1.\(J. l No.9Nn. ‘) No.Nu. Il ?'3 I TurbityI urhil)’ .. NoneNam: None NoneNunc None.\' U n t? NoneNuns None\nnu NoneNona: I NoneNum‘ None\' u n u NoneNIJIH‘. NoneNunc None\nnu None

Colourl‘nlmn' .. PalePull: Pale’allc Palel’ulc Palel’ulc LightI .!_|'.lll PaleI’nlu Brownishl€|‘n\n|i~.l| Palel’.1lc. YellowYL‘HUW Yellow‘I' L‘l ll] W Light:“l ClearL'luur Clear('lcau' yellow)‘Cllm-ﬁ yellow)L‘ll yellow)‘L:l l' yellow)‘Cllnu' brownln'uxu] yellow)i.‘ In“ yellow_\l:llLl'~'\ brownhr'm‘. n

L'Odourklml I' .. NoneNon-c NoneNunc None\unu EarthyIfurlhy None\(mu NoneNun-c Earthylfurilly None:\(‘|:L‘ Earthyl'.;li'lll_\' Earthy[{urllly Earthyl-_'.I1'lh_\ None"\tJnL' NoneNone Suspended.‘x'qwmlul SmallHmn ll SmallSmil il Small SmallSmu ll S.n.lllSmall SmallSmuil Small Small SmallHmnll SmallSmul] Small Little1 i'Itlc. Slight matter.muliu r . amountiliTil‘lll'll amountclﬂlOElll! amount:lmnuni amountillntllllil amountilmmllll amountnmmml amount.‘llllullll‘. amountLIIHUUI'Il amountiii'llULllll amountll‘ullULllll amountiillllillll: vegetable\L'ILEL'lRIEFlL‘ fibrousllln'uLIn' sedimenthmllmulll

‘ '\\ pH'nll .. 7,35 7'4517-45 7'15H 7,3 7'05 .8,3. 7,35."\“ 8'1 3-38,3 6,95{NH 7,35 7'5 7,3 I , Partslﬂuh per 100,000INLUUU -

Carbonate..t m'hnnuu‘... Nil Nil Nil Nil Nil Nil.\'il NilNi? Nil Nil Nil Nil Nil Nil

BicarbonateHlL'Kll'lHIli-JIC 28.8 16'22* 27.9 18.7 54.5 3]")43-9 - 65,4l)5'-l 46,5 48,843-5 37.6 30.6 20.2 23'1

{‘hlm'idc‘Chlorides. ... 46-4 44.2 43,8 74'4 34.4 71'47m 40.64m. 76'2 123.0Ell-l} 31-6 73'6 22.0 34,8

Sulphates.‘iulpilulm .. 22.4 17.2 18.4 25.6j-R-n 3'2 26'0if?“ 19.2l‘l'l 17.9 36,6.lﬁ'h 29.8 21.2Ill-2 8.1 8,6

NitritesNip-Hus .. Nil Nil\il Heavy”EMT 'lTracerut"; Heavy I Nil\if .. Nil Nil HeavyIIL‘.;l\_‘,' Heavyllcu\_\ TraceImus NilXil Heavy{lulu}

Nitrates.\'JII';1Ica .. Heavy Heavy”tiny HeavyHum. _\-' HeavyElma-5- HeavyllL“.|\-_\- Heavylie-my Heavyllcuvy Heavy HeavyHun;- Heavyl lt‘:l'\ 5' Heavyllcmy Presentl‘rcaunl Presentl‘rcacm

Calciumt':||'\‘ium .. 18.5 I *J-9'5ﬁ 12.8 16.3H121 11.9ll-') 16.9lb") 14.5l-l-F. ]9.7 34'2.l-l'Z 103.010—34] 21.3 7'5 13.0ll-U

Magnesium 9.0 5'25.1 6.2 ]0'5max 6.9{5"} ]2.0Hui] 10'5lU-S ]2'6lj'ﬁ ]6.4lfril 29.720-? 11'5 5,8 6,8{. -H 1 Totallr.)|e:l .. 83.3 4.“"l45.1 57,5 J\ 83.9 58.1 ‘Jl'l'J91.6 'ElJ-h79.6 ]0]'1llll'l 153.0l.".'\'[] 379.711h}? ]00.6llllJ-{I 42'6 [\[l'f‘60.5 ------I I I -.--'------"Taken“lulu-N froml'I'nm Bestow“Ram“ (1953,[1953‘ AppendixAppcmliw G){i5

. I L - -._~- --

fill up with rubble and1 are nowH - onlyi marked byi_ depressionsI u 'i‘\ with.i adjacent1 cmi moundsmnu of gypxumgypsum originaiiyoriginally takeniliixﬂ‘ outiiizi of\ V the:i wells.» DeepeningT'wqm‘fi :i; theL existingi; wells iniii 1h:the 13w.-gypsumm will ct‘i‘i'iiniicertainly increaseincrmw the yield' ' and in places like" Riba,it Balballa and' Wajir Bor where the contact between‘r-ct‘i the gypsum and the Jurassic limestones occurs at relatively shallow Llsplhx'.depths, Lhcthe weIlshulk will be made permanent when deepened to this contact. Tanks or sumps for the conservation"-.:.ii.“"i ofm raini' “i waterum 4:," haveii,..c beeni‘cc'i Animicdexcavated u:at Wajir\Mijfi‘ Bor, Abak Fin, Akal Ar, Wel \,JL‘...»I.Galul, AJilello,Mini Ibrahim1r Jim; Uri,l_"'i~ Erap,Ekaj‘ Dudumafluiuma AadMai and Wel Geris, while small natural depressionswinn.P. swimu existism? at{LC Dakhsan,ELI-,hmrk Abagaranso,Tdi‘zmsn. Saturwario,L‘iumai'iu. Wer Ade, and11L; Sabanseida,Sgi‘uf‘i‘f‘CiLid. as well as many depressionsxiv: ono'i limestone1 ' of theihc Wajir‘\\‘.1_iir‘ Beds,“Sm. ! such asin at:i Komorro,l\OIIEUT El Bey, Libiduli, etc. As surface run-off in the' ; greater partpurl ul‘of 1}“;the districtLiislriul is \iriizuli},virtually absent, thei collection of water in these '._;n\«'tanks is Lii:m‘

v i F. unreliable,unreliable. the following information on bore-holes in the areaL11”; is' \ availablekixiligmic in.r‘ theI:' rco‘rrdxrecords of the Ministry of Works and Communications:- BORE-HOLEBURE-HOLF C367-WC3677VVAHRAJIR DepthDL'pI/l in feetﬂwr LithologyLiriicif 0-18CPIS .. Limestone7 18-29$729 .. Clay :929-3873‘“: .. Grey marl 38-8534.5 .. Clay and marls BORE-HOLEBURF-HOLF C368-WAJIR("362% JWAHR DepthDani/i ii:in fed, Lithology1', iii/“Ii 2‘31i

(Li0-189“ .. LimestoneL iIN‘I‘iIDI‘iJ 18-30Mi?“ .. Clay

30-88M) K '1. .. k,ClayIn} and:Emi mmmarlsx BORE-HOLE-RIBABURE-HOI F iRllix DepthDam/1 in feetfin): Lithology (LL0-22 .. Soil 2-27 9 .. Limestone 9-27“J 727 .. Crystalline‘i‘piniline rockmick (Gypsum{(ijmsum ?)‘_’. 27-44‘7 4.4 .. Tough'I'uugh sin}clay midand pebblespciibia 44-66444:5 . .. LimestoneLHTRNECI‘Q

BORE-HOLE-WBURLHOLEWWM[RAJIR BORBUR Depth[Land] inI‘ll feetfi’L'.’ LithologyLi:‘.ii.‘iiiii""i 0-260‘26 i .. KunkarKunkiiz‘ 26-3626—36 i .. Detritus andmm pebbles 3636-4646 . .. LimestoneLinxsiunc 46-5746757 . .. LimestoneL‘A‘ ‘IUCHICI‘E 57-6251—62 . . Yellow\VcHoi“ claychi). and bouldersbi‘iiiiki'ﬁt's ofm‘ limestoneiimcsmnc (12—40862-408 .. Limestone'

---1.= - ,. - ~ " -I ._-~

.-\l'71‘l'After 1the geological survey of the Wajir area a bore-hole was drilled“i .11at Lullufilu.Gherille, near:71‘211‘17.the SomaliaSomali: '1\\border,.1... to a depth of 450 feet without encountering any_' \-\'ESIC.".water. FromFrom“ 1110the log,lug. which“hich llf‘llx‘wxx.follows, itl1 seems that it pierced Pleistocene deposits only and indicatesindicatcx .1. .1 the.TL thickness.1". 31.1mm 1'11of theihc d\‘\deposits1a 1of‘1' that”it age in the area.

BORE-HOLE[3051141131 F (21141.7{1171111111C2644-GHERILLE1 Depth[MW/'1 in feeth us Lithology 070- :1)20 .. Red kunkar 20—10:)20-100 Yellowish buff gritty01“”1} c.1kuxouscalcareous‘lr‘w 1.1.1)clay with\\.1l‘. unmilsmall water-worn quartzitic111C pebbles,pebbles. and some non-[101% calcareous greenish1.1 51:1}clay Pdlckpellets IOU100-12012‘.) .. Coarse quartzitic“\11111‘1'1111hsand with small kunkal‘kunkar .‘li‘ipschips 120-1601207160 .. Buff-grey gritty mlguz'mjmzcalcareous\ clay1; 1607181}160-180 .. Coarse quartzitic:1,1:'V.<111C mudsand with111131 kunkarl1;11‘13uu‘:l1311\chips 180-20018072)") .. Buff-grey‘ 1‘ 3:11;. calcareous1111;11:0l clay3219‘ with\\i:h finetine :11‘1:grit 200-2601007260 .. Yellowish brown calcareous clay withv.31.“ KJII‘ALUkunkar and111111 greenish calcareous clay pellets, and111711 some small rounded quartz pebbles 260-280 .. Buff gritty ﬁcalcareous‘lCLJKSC-ll‘ Cr:clay 280-300 .. Coarse quartzitic“1111;“ \JIM‘.sand with1:. .11 ~11:small.l', lumpslumpx of k1111'l-.1‘11‘kunkar limestone‘jzl‘a'. 11; .mdand 3.11;large ".xcll-z‘uumledwell-rounded quzm/quartz pcbb‘lw;pebbles 300-32030(17310 .. Yellow calcareous clay 330320-360360 .. Slightly calcareous brown clay 11 ‘ n . 31,1)360-400400 .. Reddish brownl 1Jul. non-calcareouslull 1.111111% LLclayj» 135077400(380-400 ft.2‘1. sample-a . lump112m of1, kunkar711";':]’ limestone)l'mu‘ﬁfunc) I 400450400-450 .. Brown non-calcareous clay, red ferruginous sand and small lumps of kunkar limestone. Lower parts '\ with small water-worn quartzitic pebbles I

VU\ H~4§1§FLRENV,..REFERENCES "

Ayers,X}c:\. F.I. M.,\l,. 1952-"Geology[95: ”(mung 1::of 1h;the Wajir-Mandera'1‘, 1;,1'7\l,1'1lj1'111 District,l) «“111. _\.:11;.rc.;\1North-east Kenya".1\1.j Rept.Ri‘pl. No.NH. 2:.22, 001"].Geol. 5113Surv., Kenya.krni ,1. Aylmer,.\}ll'lTCF. L.,l... 1911-"The1911*”1l12 CountryL-wllllll‘} BetweenBring: the.‘Q Juballﬁlw RiverRmcv “mland Lake111x: Rudolf". Geogr. Journ.,.I1.-1';1'n., Vol. XXXVIII,XXXVI”. pp.1‘17, 289-296.1891451.

Baker,H11.“.C B.R. H.,H . andwt’lxl E.1" P.P Saggerson,1‘1 9WM 11.11958-"Geology‘ vi: 11‘. L of.1 the EIE? Wak-Aus‘1 , ‘1 Mandu!a" “z. 2.: Area". Rept.Regal. No..\0. 44‘.44, Geol.cn'. Surv.,51:11. Kenya.lxcny; Bestow,Halon. T. T.,.. 1953-"The“Tl“: Geology.Geology WU.and HydrologyElj11l1‘olnzj» 1:3'of Wajir\\,1 District".Dixll'.‘ (Unpublished reportrcpm'l mlof the Hydraulic}’[)Lll‘1:LlllL‘ Branch,B1‘.1:1;l1. Ministry\iizlixtrj. 111‘of Works,“7171». Nairobi.)\fzimbi.‘

Busk,{Ell-wk. H. G.,(,1. 1939-"Notes1193‘) ~"NHMN on the Geology of the North-eastern>‘;.:\ICT'1‘; Extremity[\1 :‘cm. ‘ of the NorthernNorlhern FrontierHmnliel' Province,PI‘JHHC... Kenya Colony". . Geol.(311111.111.Mag., Vol.\‘nl. LXXVI,1_.\:X\=I. pp. 263-269.203.211».

Busk,151:5'11. H. (3..G., 11mland .l.J. P.l’. Verteuil,\cftcl”. 1938-"Notes. "\cx on1111 the1.1: 11mlGeology11).". and ()ElOil ProspectsPrmpcch ulof L Northern\1’11’1‘1cm Kenya".Kc1‘11.1"_ D'ArcyDAN}. ExplorationExplnmlf‘ Co.,h 1 Ltd., and Anglo-Saxon\1';ll‘-S.1\1m Petroleum{321111154111 (’11..Co., Ltd.1.111. 1L2np11lwllsl1c1l(Unpublished.)ﬂl

—1

7..

r 17‘ Caswell,(1 usual]. P.1’. V.,\1._ 1953-"Geology1953 . "(Jeulogy of the Mombasa-Kwale r Area".r Report:‘1 No.\11. 24.24, £13.11.Geo!. Surv.,Surxz. Kama.Kenya.

Dacque, E.,.;1“11land E.F. Krenkel,K1‘1211l1cl. 1909-"Jural‘lllW‘ 9‘.l:11‘; and;1*1_l Kreide{\"1‘111' in" Ostafrika". Neues Jahr. f. Min..‘JEH. Geol. Pal., Bei!.131‘11. Bd. 2‘.28, pp.gm 150-232.ISM-:3:

...... - ---- r

34. -r

Dixey,[)HL’}. F.,l-'.. 1944-"Hydrographicall" - iiiH}'LlY"-"L1L‘|hiCdi SurveySLIJ'VC} ofcf the NorthernNarahcrri FrontierFl‘C-[ZIICT District,District. Kenya".Kenya” ReportRi'pml 10to theEli-r Public WorksWi‘i'iw Department,Department. Nairobi.\aim'h; (Unpublished.){L.'I‘:pL1hiiS‘ncd.'I 7 ~ 1948-"GeologyI‘M-33 ”'(jculngy miof Northern.\'(J"ihcm Kenya".Kern-.1". ReportRepurl No.Kn. 15,35. Gaul.GeoI. Suri...Surv., Kenya.Kema. Dodson,Dndwn. R. G.,Li.. 1955-"GeologyI955 ~“(jcoiog1 ofiil‘ the[he NorthNilTlh KituiRilui Area".Arm". ReportRupurl No.NH. 33.33, Geol.Cool. Surv.,SLli‘\'.. Kenya.Kemu. Haywood,H;ij.\\'m:-.j1. C.f'. W.,\\.. 1913-"TheTil} 4't Loriani.L"-ri:m Swamp".Sunriip“. Geogr.(Erna-r. JOllrn...-'.~.-,i.I-.ri, Vol.\"01. XLI,XL]. pp.pp 463-468.“3—463 Joubert,Jnu'hcr‘i. P.,P.. 1960-"GeologyI‘ii‘i 4‘Licn'i oi‘of lhcthe Mandera-Damassa.'\]aInici';i—I)=_uii;ix>;{ Area".:‘xruai". ReportRep-01x No.N0. 48.48, Geol.Gen]. Sun;Surv., Kenya. Mason,\Iuwn. P.,P. 1955-"Geology1955 7"Gcnlngy (:1of methe Meru-Isiolo\iL‘FIIviHUJU Area".Arm". ReportRcimri No.\0. 3i.31, Gen}.Geol. Surv.,Bury. Kenya.Kern-.1. Parkinson,I‘ut'kimon. J..J., 192o-"ReportI‘JZH “Report inon themy (mule-143'Geology .i:uiand (mi’igi‘npliyGeography .ifof the Nurlhei'nNorthern Part of , ‘-..-.:the ELEHIEast AfriqdnAfrican I’miuqim'utc”.Protectorate". (hi.CoI. Rep. Misc.,Him. .\0.No. :91.91, (and.Cmd. T29.729.

- 1922-"Problems[92: J‘tlcms ufof Geology in British EastEdd. Africa". Jam-ii.Journ. ufof Lin-the AfricanAJ'J’i'ii'v'fi‘ I Society,Adria-‘1, pp. 105-114.INS—5H. I I Ruhfnmn. CL \‘\',. |"532~“Sniix. Their Origin. ( onstgtuicn din-(E ('l.ix\ific;i1ioiz". I Robinson, G. W., 1932-"Soils. Their Origin, Constitution and Classification". I Saggerson,Suggcrmn. E.In, P.,P.. and .l.J. M.\i. Miller,\iili::r. 1957-"Geology1'45? . "(icnlrgju at?of Lficthe Take.hhzi—WcrgududTakabba-Wergudud Area".Arc-.1”. Report No..\n. 40.40, (imi.GeoI. Sun"Surv., }\C|‘.:\;l.Kenya. ci'unim.Stefanini, (1..G., 192:"1925-"Sur“Hi: la|.: (fumiiiiiiinnConstitution (Jin'ngiqusGeologique dcde :1la Su'imlicSomalie Italiennelliiiicnne Nitric}Merid- immilc".ionale". CnmplcsComptes RCHdLIQ.Rendus, XllllhXlIIth lnt.I:1:. howl.GeoI. (ungrcxx.Congress, 1922,i932. pp. IJJSLJ-HNZ.1,059-1,072. Ti'lcl'npmii.Thompson, A.."\. 0,.0., 1956-"Geologyl'fihm "(iti‘h‘gy Li‘fof themu Malindi\iLiiillLii Area".\I‘cL-f‘. Reportciirl No..\n. 3h.36, CCU].GeoI. Surv.,Sun” Kenya.Kt:fl};l. '. Thompson,lihmnpsm‘. A..-\_ 0..0., and R. (.u.G. Dodson,Dnu'snn. 1958-"Geology11.155 Thain-g; of thythe Derkali-Melka[)erkaiifllelku Murri Area".Area". cnrlReport N0.No. 7.}.43, (iuol.GeoI. Surv.,Sun; Kenya. ifl'ii f"-"|.’1‘-|196o-"Geology"(:cfi-i-Jg'. u!of :i:-:the MirBur XI:1:\li‘7["li>iJ|Mayo-Tarbaj Arc-:1",Area". RCPJHReport .\\i.No. 4.7.47, (JCULGeol. Riiz‘y.Surv., Kenya. '!Twenhofel,ucnhniici. W. H.,H. 1939-"PrinciplesJ'JF‘Ji'Pi'ing pin ailof {\cdiificnimimi"Sedimentation".

G.P.K(i.i’.K 1279-1m-5/60217‘)» [:11 75 NJ

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