I I
72-15,173
BEHLING, Robert Edward, 1941- PEDOLOGICAL DEVELOPMENT ON MORAINES OF THE MESERVE GLACIER, ANTARCTICA.
The Ohio State University in cooperation with Miami (Ohio) University, Ph.D., 1971
Geology
University Microfilms,A XEROX Company , Ann Arbor, Michigan PEDOLOGICAL DEVELOPMENT ON MORAINES
OF THE MESERVE GLACIER, ANTARCTICA
DISSERTATION
Presented In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
By
Robert E. Behling, B.Sc., M*Sc.
*****
The Ohio State University 1971
Approved by
Adv Department f Geology PLEASE NOTE:
Some pages have indistinct print. Filmed as received.
University Microfilms, A Xerox Education Company ACKNOWLEDGEMENTS
This study could not have been possible without the cooperation of faculty members of the departments of agronomy, mineralogy, and geology, I wish to thank Dr. R. P. Goldthwait as chairman of my committee, Dr. L. P. Wilding and Dr. R. T. Tettenhorst as members of my reading committee, as well as Dr. C. B. Bull and Dr. K. R. Everett for valuable assistance and criticism of the manuscript. A special
thanks is due Dr. K. R. Everett for guidance during that first field season, and to Dr. F. Ugolini who first introduced me to the problems of weathering in cold deserts.
Numerous people contributed to this end result through endless discussions: Dr. Lois Jones and Dr. P. Calkin receive special thanks, as do Dr. G. Holdsworth and Maurice McSaveney. Laboratory assistance was given by Mr. Paul Mayewski and R. W. Behling. Field logistic support in Antarctica was supplied by the U.S. Navy VX6 Squadron and the staff of the United States Antarctic Research Program in McMurdo.
Financial assistance through the National Science Foundation Grants
Nos. GA-1158 and GA-4029 made this study possible and is gratefully acknowledged.
And yes, thanks to my wife Mary for help during these last typing stages,
ii VITA
September 11, 1941 Born, Milwaukee, Wisconsin
1963 « B.Sc., Mathematics, Geology, The University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
1963-1965 N.D.E.A. Fellow, Geology, Miami University, Oxford, Ohio, in cooperation with The Ohio State University, Columbus, Ohio
1965 M.Sc., Geology, Miami University, Oxford, Ohio
1965-1966 N.D.E.A. Fellow, Geology, The Ohio State University, Columbus, Ohio
1968-1969 Instructor in Geology, Capital University, Columbus, Ohio
1965-1970 Graduate Research Associate, The Ohio State University, Columbus, Ohio
1970-1971 Instructor in Geology, Capital University, Columbus, Ohio
1971- Assistant Professor, West Virginia University, Morgantown, West Virginia
iii PUBLICATIONS
Behling, R, E., 1965, A detailed study of the Wisconsin stratigraphic sections of the upper Lamoille valley, northcentral Vermont: M.Sc. thesis, Department of Geology, Miami University, Oxford, Ohio.
Shilts, W. W., and Behling, R. E., 1967, Deglaciation of southern Vermont and adjacent highlands: (abs.) 1967 Annual Meetings of the Geological Society of America, New Orleans, Louisiana, G. S. A. Special Paper No. 115, p. 203.
Everett, K. R., and Behling, R. E., 1968, Pedological study in Wright Valley, Southern Victoria Land: Antarctic Journal of the United States, v. Ill, p. 101-102.
Behling, R. E., and Calkin, P. E., 1969, Chemical-physical weathering, surficial geology, and glacial history of the Wright Valley, Victoria Land: Antarctic Journal of the United States, v. IV, p. 128-129.
Calkin, P. E., Behling, R. E., and Bull, C. B., 1970, Glacial history of Wright Valley, Southern Victoria Land, Antarctica: Antarctic Journal of the United States, v. V, p. 22-27.
Everett, K, R., and Behling, R. E., 1970, Chemical and physical characteristics of the Meserve Glacier morainal soils, Wright Valley, Antarctica: an index of relative age?: in International Symposium on Antarctic Glaciological Exploration- flSAGE), Hanover, New Hampshire, Sept. 1968, p. 459-460.
Behling, R. E., and Calkin, P. E.,1970, Wright Valley soil studies: Antarctic Journal of the United States, v. V, p. 102-103,
Behling, R. E., 1970, Relative dating of glaciations in Wright Valley, Antarctica, by pedological analysis: (abs.) 1970 Annual Meetings of the Geological Society of America, Milwaukee, Wisconsin, v. 2, p. 491.
Behling, R. E., 1971, Rate of chemical weathering in a cold desert environment: (abs.) 1971 Annual Meetings of the Geological Society of America, Washington, D.C., v. 3, p. 501-502.
iv TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS...... ii
VITA...... a ...... ill
PUBLICATIONS...... iv
TABLES...... ix
FIGURES ...... xiii
CHAPTER
I. INTRODUCTION ...... 1
A. The Ice-Free Region of Southern Victoria Land 1
B. Statement of the Problem • • ...... 5
II. WRIGHT VALLEY: PHYSICAL GEOGRAPHY, GLACIAL GEOLOGY, PEDOLOGY - PREVIOUS INVESTIGATIONS AUGMENTED BY THIS WORK...... 11
A. Physical Geography ...... •••• 11
B. Climate...... 16
C. Bedrock Geology...... 23
D. Glacial Geology...... 29
(1.) Introduction...... 29
(2.) Glaciations from the West: Wright Upper Glaciations...... 33
(3.) Glaciations from the East...... 36
(4.) Advances of Valley-sided Glaciers. • . 37
(5.) Fossil Record in Quaternary Marine Deposits 39
v Page
(6.) Quaternary Climate Changes ...... 42
E. Soils in Wright Valley ...... 43
(1.) Introduction and Classification. .. . 43
(2.) Organic Constituents of Antarctic Soils...... • ...... 47
(3.) Salts in Antarctic S o i l s ...... 50
(a.) Location of Salts...... 50
(b.) Movement of Salts...... 51
(c.) Sources of S a l t s ...... 53
(4.) Characteristics of Soils of Ice-free Regions...... 56
III. MESERVE GLACIER: PHYSICAL GEOGRAPHY, GLACIAL GEOLOGY, AND PEDOLOGY ...... 60
A. Physical Geography ...... 60
B. Glacial Geology...... 62
C. Soils of the Meserve Glacier Area...... 75
IV. PHYSICAL PARAMETERS OF PEDOLOGICAL DEVELOPMENT .... 79
A. Soil T e m p erature...... 79
B. Soil Moisture...... 85
C. Soil A i r ...... 89
D. Weathering of Boulders on Moraine Surfaces . . 89
E. Pebble Lithologies: Labile versus Resistant . 94
F. Particle-Size Distribution 94
V. CHEMICAL PARAMETERS OF PEDOLOGICAL DEVELOPMENT .... 100
A, Eh, pH, Abrasion pH, and Electrical Conductivity ...... 100
(1.) Oxidation-Reduction Potential. .... 100 vi Page
(2.) Acidity-Alkalinity...... 101
(3.) Abrasion p H ...... • ••••••• 101
(4.) Electrical Conductivity* ••••••• 106
B. Soluble Salt and Specific Ion Determinations . 106
(1.) Soluble Salt ...... 106
(2*) Specific Ion Determinations...... 106
C* Free Iron Oxides ...... 109
D* Heavy Mineral Analysis ...... ••••• 115
E. Elemental Analysis by X-Ray Fluorescence • • ■ 117
(1*) Titanium and Z i r c o n i u m ...... 118
(2.) Potassium...... 124
(3.) I r o n ...... * 126
F. Clay Mineral Determinations...... 130
VI. CONCLUSIONS...... 136
A. Present Weathering Processes in the Wright Valley Cold Desert ...... 136
(1.) Physical Weathering...... 136
(2.) Chemical Weathering...... 142
(3.) Authigenic Clay Minerals ...... 149
B. Relative Ages of Alpine Glaciations of Meserve Glacier...... 152
C. Implications to Axial-Alpine Glaciation Relationships...... 156
(1.) Introduction ...... 156
(2.) Axial Glaciations from the West. . . . 157
(3.) Axial Glaciations from the East. .. . 159
vii Page
(4.) Alpine Glaciations•••••••••• 161
(5.) Variations in Weathering Rates in Wright Valley...... 161
(6.) Summary...... 161
APPENDIX...... 164
A. Surface Weathering Criteria on Moraine Crests. East Side. Meserve Glacier ...... 165
Surface Weathering Criteria on Moraine Crests. West Side. Meserve Glacier ...... 166
B. Soil Profile Descriptions...... 167
Alpine I (WVMC 6)...... 168
Alpine II (WV 5 ) ...... 171
Alpine III (WV 1)...... 178
C. Particle-size Distribution; Weight Percent...... 186
D. Soil Temperature Readings...... 190
E. K-Ar Dating of Volcanics from Wright Valley by R. Fleck ...... 199
REFERENCES...... 200
viii TABLES
Table Page
1. Meteorological Observations at Vanda Station, Lake Vanda, Wright Valley. Partial Data: November 1968 to July 1970 ...... 6
2. Percent Mean Cloud Amounts at Moraine Station, Meserve Glacier, Summer, 1965-1966...... • ...... 20
3. Monthly Mean and Extreme Temperatures (°C) at Base and Glacier Stations (Stevenson Screens)...... 21
4. Bedrock Chronology of Wright Valley ••••* ...... •• 26
5. Glaciations in Southern Victoria Land ...... ••••• 30
6. Correlation Chart and Chronology of Glacial Events in the McMurdo Sound Region...... 34
7. Possible Climatic Changes in the Vicinity of Meserve Glacier during the past four million years...... 46
8. Soils of the Cold Desert...... 48
9. Identification and Location of Salt Efflorescences Described from Ice-free Areas of Antarctica ...••• • 32
10. Physical Weathering Criteria, based on condition of larger clasts...... 74
11. Soil Moisture Content ...... 86
12. Average Gas Analyses of Air: Taylor Valley and McMurdo Station ...... 90
13a. Particle-size Analysis and Sand/Silt Ratios, Based on Less than 2 mm Fraction...... 96
13b* Particle-size Distribution of Coarse Fraction Greater than 2 mm...... 97
ix Table Page
14. Oxidation-Reduction Potential in a 1:1 soiliwater slurry...... 102
15. Electrical Conductivity of a 1:1 soil:water Extract • • • • 107
Iron Oxides and Hydroxides...... Ill
17. Free Iron Oxides Extracted by Oxalate (Fe ) and Dithionite- citrate (Fe^) Treatments from Clay-size Particles ...... 113
18. Heavy Mineral Separation with the Franz Isodynamic Separator: 0.105-0.125 mm Size-fraction...... 116
19. Elemental Analysis: Titanium and Zirconium,'Very-Fine-Sand Fraction: 75-50 p ...... 119
20. Elemental Analysis: Titanium and Zirconium, Coarse-Silt Fraction: 50-20 p ...... •...... ••••••••• 120
21. Elemental Analysis: Titanium and Zirconium, Medium-Silt Fraction: 20-5 p . •••••••...... 121
22. Elemental Analysis: Titanium and Zirconium, Fine-Silt Fraction: 5-2 ...... 122
23. Summary of Elemental Analysis for Titanium and Zirconium; Average Values, 10 cm Intervals ...... 123
24. Elemental Analysis: Potassium *.••••.••...•• 125
25. Elemental Analysis: Iron ...... 128
26. Semi-quantitative Estimations of Clay Minerals...... 133
27. Semi-quantitative Clay Mineral Concentration...... 134
28. • Interstratified Mineral X-Ray Diffractogram Analysis: Glycolated after Removal of Iron Coatings ..••••••• 135 87 86 29. Sr /Sr Ratios of Water-Soluble Salts and Total Salt-free Soil, and the Lithologic Composition of Moraine Samples, Meserve Glacier, Wright Valley...... 144
30. Partial Chemical Analyses of Snow and Ice: Wright Valley and South Pole Samples. .••••••.•••••••••• 146
31. Examination of Surfaces of Magnetite Crystals ...... 148
x Table Page
32a. Relative Age Estimations Based on Salt Concentration and Reaction Kinetics ...... 153
32b. Relative Age Estimations Based on Potassium Composition and Reaction Kinetics ...... 154
33. Revised Glacial Sequence Based on Weathering and Soil Studies ...... 158
34. Field Observations of Present Summer Climate Conditions on Drift Surfaces in Wright Valley...... 162
xi FIGURES
Figure Page
1. Outline Map of Antarctica...... 2
2. Ice-free Region of Southern Victoria Land...... 3
3. Longitudinal Profile of Wright Valley. • • • ...... 12
4. Wright Valley, looking west toward inland ice-plateau. . . 14
5. Wright Valley, looking east toward Mount Erebus and Ross Island. ..•••••.••• ...... •••• 15
6. Meteorological Parameters at Base (Moraine) and Glacier Stations, Meserve Glacier, November 1965-February 1966 . • 22
7. Bedrock Geology of Wright Valley ...... 24
8. Extent and Tentative Correlation of Glaciations in Wright Valley, Antarctica. ••••*•...... • 32
9. Diagrammatic Relationships between Axial and Alpine Glaciation Deposits, and Pit Sites, Meserve Glacier, Wright Valley...... 40
10. Postulated Climatic Changes in Antarctica During the Past 5 x 10 Years ...... 44
11. Meserve Glacier...... 61
12. Meserve Glacier Snout, (a.) Plan of the Ice-tongue. (b •) Cross-section of the Ice-tongue and Alpine II and Alpine III Moraines...... •••• 63
13. Topographic Profile and Projected Cross-section of Alpine II, Ila, and III Moraines on the East Side of Meserve Glacier...... 64
14. Crest of Alpine I Moraine and WVMC 6 Profile •••••.. 70
xii Figure Page
15. Surface of Alpine III Lateral Moraine; view upslope from WV 1 soil pit ...... 72
16. Crests of Alpine II, Ila, and III Moraines, looking downs lope from an elevation of 900 ...... 73
17. Selected Temperature Profiles: Alpine III Moraine, 1969 • 80
18. Selected Temperature Profiles: Alpine II Moraine, 1970. . 81
19. Diagrammatic Cross-section of Theoretical Soil Profile . . 84
20* Cavernously Weathered Metasediment Boulder, Alpine III Moraine, East Side, Meserve G l a c i e r ...... • 92
21. Surface of Alpine III Moraine at Site of WV 1 Profile. . . 93
22. Particle-size Analysis ...... 98
23. Clay-size Particle Distribution with Depth ...... • 99
24. Soil p H...... 103
25. Abrasion pH•••••...... •• 105
26. Electrical Conductivity and Total Salt Content by Acid Digestion...... 108
27. Relative Ion Concentration: Chlorine and Sodium ..... 110
28. Ratio of Extractable Iron Removed by Oxalate and Dithionite-citrate Treatments...... 114
29. Potassium Content as a Function of Iron-rich Heavy Mineral Fraction ...... 127
30. Iron Content as a Function of Light Mineral Fraction . . . 129
31. Metasediment Boulder Planed to Surface of Alpine III Moraine, East Side, Meserve Glacier. •••••..•••. 138
32. Alpine I Profile (WVMC 6)...... 170
33. Surface of Alpine II Moraine, looking downs lope from WV 5 pit site...... 173
34. Crest of Alpine II Moraine 50 m above WV 5 pit site. . . . 174
xiii Figure Page
35. Upper Portion of WV 5 Profile, Alpine II Moraine • • ■ • • 175
36. Lower Portion of WV 5 Profile, Alpine II Moraine . • • • • 176
37. Ice-cemented Layer, WV 5 Profile, Alpine II Moraine. . . . 177
38. Surface of Alpine III Moraine, downslope from WV 1 soil pit ...... 180
39. Upper Portion of WV 1 Profile, Alpine III Moraine...... 181
40. Upper Portion of WV 1 Profile, Alpine III Moraine...... 182
41. Completely Shattered Metasediment Boulder ia WV 1 Profile, Alpine III Moraine ...... 183
42. Free Salt-crystals at Depth in WV 1 Profile, Alpine III Mo r a i n e ...... 184
43. Salt Encrustations beneath Pebbles in WV 1 Profile, Alpine III Moraine ...... 185
xiv CHAPTER I
INTRODUCTION
A. The Ice-Free Region, of Southern Victoria Land
Antarctica is a roughly circular land mass with a diameter of 6 2 4500 km and an area of 14 x 10 km . The Antarctic Peninsula and two embayments, the Weddell Sea and Ross Sea, break the circular outline
(Fig. 1). Two major portions of the continent are referred to: East
Antarctica, comprising three-quarters of the total land area, and West
Antarctica, which lies west of the Transantarctic Mountains and the
Filchner Ice Shelf (Fig. 1). Reviews of the geology and geomorphology of Antarctica are numerous (e.£., Adie, 1964; Ford, 1964; Harrington,
1965; and Nichols, 1966) and only information pertinent to the ice- free regions of southern Victoria Land (Fig. 2) will be presented here.
More than 957. of the area of the Antarctic continent is covered by ice and snow. The ice-free areas exist along the margins of the ice-sheet and as nunataks. The Transantarctic Mountains bound the ice-sheet of East Antarctica and extend from 70° S to 83° S (Fig. 1).
They contain many ice-free areas, the largest of which is about 2 4000 km in southern Victoria Land (Fig. 2).
This largest ice-free area lies between 77° S and 77°45' S, and
160° E and 163° E, and includes three major valley systems: Taylor,
Wright, and Victoria (Fig. 2), Taylor Valley is ice-free for 35 km
1 Wtddtll So Tilehner let *-LSh*If. -■
EAST ANTARCTICA
In s Kntx let Cent Skill
ini s«>~fY Itn I. \ INVESTIGATES Vietirii
500 110
Figure 1. Outline Map of Antarctica 3
Clark Cl-^
lihyriBtk talc
Figure 2. Ice-free Region of Southern Victoria Land.
Glaciers: Bartley (B)t Meserve (M), Hart (H), Goodspeed (G), Denton (D). -I • Ice-free Region of Southern Victoria Land. lers : Bartley (B), Meserve (M), Hart (H), Goodspeed (G), Denton (D).
i 4 and opens directly onto McMurdo Sound. It is bounded on the south by
the Kukri Hills and on the north by the Asgard Range. Wright Valley
is ice-free for more than 50 km and is separated from McMurdo Sound by
the Wilson Piedmont Glacier. Wright Valley is bounded on the south by
the Asgard Range and on the north by the Olympus Range.
Wright Valley and the Victoria Valley system to the north are
connected through the Olympus Range by Bull Pass. The Victoria Valley
system consists of five interconnected valleys: Upper Victoria, Lower
Victoria, Barwick, Balham, and McKelvey. Between the Barwick and
McKelvey valleys is the Insel Range. The Wilson Piedmont Glacier also
separates this valley system from McMurdo Sound. The Victoria Valley
system is bounded on the south by the Olympus Range and on the north
by the St. Johns Range.
Portions of the ice-free area west of McMurdo Sound, particularly
Taylor Valley, were first visited by field parties of Scott's
expeditions of 1901-04 and 1910-13, and Shackleton's expedition of
1907-09. Geologists from Victoria University of Wellington,
New Zealand, initiated investigations of Wright Valley in the summer of
1958-59. Since this time field parties from several nations have
worked in Wright Valley.
Bull and others (1962) have shown that the deglaciation was
caused by a decrease in the surface level of the inland ice plateau
with consequent emergence of high rock-thresholds at the western ends
of the valleys, cutting off the supply of plateau ice to the valley
glaciers. With the exposure of increasingly larger areas of rock,
solar radiation slowly ablated any remaining stagnant ice of the 5 outlet glaciers. A present positive annual net radiation balance in 2 the ice-free region, (8,712 ly (1 ly = 1 cal/min/cm ) in 1969-70 at
Vanda Station (Table 1))* combined with relatively warm and dry katabatic west winds and low winter precipitation, accounts for the continued ice-free nature of the area.
B. Statement of the Problem
Wright Valley, one of the U-shaped ice-free valleys of southern
Victoria Land, is about 50 km long and ranges in width from 3 to 5 km.
It was shaped by outlet valley-glaciers from the inland ice of East
Antarctica and has since received sediments as a result of numerous glaciations which have partially occupied the valley. The chronological sequence of glaciations and the development of soils on the glacial deposits in Wright Valley are examined in this report.
An effective organic component is lacking in the pedogenic processes in the Wright Valley cold desert, and the soils are ahumic
(Tedrow and Ugolini, 1966). These ahumic soils developed on a wide variety of glacial, fluvial, and lacustrine deposits resulting from glaciations in the valley since the valley-cutting stage and provide a means of comparing the chronological sequence of deposits.
Many authors (e^.£., Nichols, 1961a; Bull and others, 1962; Calkin and others, 1970) have studied the complex history of recurring axial and alpine glaciations in Wright Valley. After valley-cutting, axial glaciations (ice-flow in the direction of the main axis of the valley) occurred when the inland ice-sheet was sufficiently high to supply and maintain an eastward-flowing outlet glacier, and when ice in
McMurdo Sound extended westward into Wright Valley. Alpine glaciers 6
TABLE 1 . Meteorological Observations at Vanda Station, Lake Vanda, Wright Valley. Partial data: November 1968 to July 1970. Unpublished data courtesy: Graig, R.M.F., and Thompson, D.C., 1969; Bromley, A.M., and Thompson, D.C., 1970; New Zealand Meteorological Services.
Nov. Dec. Jan. Feb. Mar. Apr. May 1968 1969 Temperature 0900 (°C) (From 23“ Mean + 1.0 -6.8 -18.8 -32.1 -34.3 r,d OI° - 0.6 Mean Maximum +2.7 +4.5 -3.1 -14.8 -28.7 -28.5
Mean Minimum -4.0 -2.5 -10.5 -24.9 -35.5 -40.0
Extreme Maximum +9.5 +8.3 +3.6 -3.4 -8.9 -8.0 30ch 22nd 13th 29th 2nd L6lh Extreme Minimum -9.5 -7.3 -21.8 -34.6 -46.7 -48.8 6th 29th 28th 17th 23rd 10th Mean Wind Speed (Knots) 12.4 12.0 7.5 3.0 3.6
Maximum Cust 170/51 270/50 260/48 270/54 270/71 270/52 (Direction/Knots) 29th 12th 14th 24th 25th 4 th Date 230/54 26th Number of Gales 0 2 0 4 2 1
Days of Snowfall 3 3 4 8 4 9
Days of Adjacent Snow 14 14 11 12 7 9
Days of Snow Lying 0 0 1 14 12 13
Cistern Pressure (mbs) Mean 0900 990.2 981.8 979.5 985.8 982.7
Mean (Thrce-hourly totals) 977.8 900.1 990.0 981.5 979.4 985.4 982.5
Extreme 0900 1002.1 994.0 1001.2 L000.2 998.4 Lowest 0900 978.8 966.5 960.7 964.0 962.4
Cloud Cover (Mean) tenths 4.6 4.3 3.8 3.6 4,2 2.9 4.0
Solar Radiation (Langleys) 266 0
Net Flux Radiation (Ly.) -2151 -2633
Soil Flux Radiation (2")(Ly.) ■744.7 -535.5
Mean Relative Humidity 0900 43 46 53 61 71 60 (7.) Soil Temperatures (°C) Mean: 6" Depth -5.4 -17.1 -26.2 -31.7 Mean: 10* Booth ■d 1 *9... -12.9 -15,7 . 7
TABLE 1. Meteorological Observations at Vanda Station, Lake Vanda, Wright Valley. Partial data: November 196S to July 1970. Unpublished data courtesy: Graig, R.M.F., and Thompson, D.C., 1969; Bromley, A.M., and Thompson, D.C., 1970; New Zealand Meteorological Services.
June July Aug. Sept. Oct. Nov. Dec. 1060 Temperature 0900 (°C) Mean -35.6 -39.3 -39.2 -32.8 -18.5 -5.8 +1.3
Mean Maximum -31.2 -33.9 -34.1 -26.7 -12.6 -2.1 44.4
Mean Minimum -40.0 -44.6 -44.2 -38.8 -24.3 -11.3 -1.8
Extreme Maximum -6.1 -12.3 -6.9 -5.7 40.7 +2.3 48.5 5th 15th 30“ 30th 29“ 19“ 13“ Extreme Minimum -49.4 -56.9 -52.4 -46.0 -33.2 -17,9 -7.2 30th 12th 20th 18“ 20“ 1st 1st Mean Wind Speed (Knots) 4.1 8.9 4.5 6.2 9.6 14.0 12.8
Maximum Gust 260/50 280/72 280/78 210/65 270/63 270/58 210/53 (Direction/Knots) 7th 25“ 31st 30“ 29th 25426“ 13“ Date
Number of Gales 0 8 3 2 3 2 0
Days of Snowfall 7 3 6 0 2 2 11
Days of Adjacent Snow 11 6 6 8 10 12 22
Days of Snow Lying 15 12 23 0 5 0 0
Cistern Pressure (mbs) Mean 0900 992.6 973.6 972.8 976.3 976.4 972.5 977.8
Mean (Three-hourly totals) 992.6 973.3 972.7 976.2 975.9 972.2 981.6
Extreme 0900 1018.1 999.3 988.5 993.5 991.1 984.2 993.1 Lowest 0900 964.3 950.7 951.6 955.9 955.8 964.5 961.1
Cloud Cover (Mean) tenths 3.2 2.2 3.3 3.8 3.5 4.3 5.6
Solar Radiation (Langleys) 0 0 108 841 . 6539 L5257 18489
Net Flux Radiation (Ly.) -2687 -4184 -2341 -2104 -206 +5791 +7284
Soil Flux Radiation (2")(Ly.) -591.4 -443.4 -398.1 -213.8 +310.5 +678.7 +792.1
Mean Relative Humidity 0900 78 78 71 83 77 65 39 ( ’/,) Soil Temperatures (:C) Mean: o" Depth -32.3 -39.4 -38.5 -33.4 -21.2 -7.4 +0.9 Mean: 10' Denth -21.9 -24.7 -26.6 -27.3 -26.6 -22.1 -18,2 8
TABLE 1 . Meteorological Observations at Vanda Station, Lake Vanda, Wright Valley. Partial data: November 19641 to July 1970. Unpublished data courtesy: Graig, K.M.F., and Thompson, D.C., 1969; Bromley, A.M., and Thompson, D.C., 1970; New Zealand Meteorological Services,
Jan. Feb. Mar. Apr. May June July 1970 Temperature 0900 (°C) Mean ,+2.4 -5.2 -18.2 -30.2 -25.1 -25.0 -36.9
Mean Maximum +5.7 -1.5 -13.6 -25.7 -18.7 -19.2 -33.1
Mean Minimum -1.8 -8.8 -22.9 -34.7 -31.4 -30.9 -40.8
Extreme Maximum +10.4 +4.4 -0.1 -27.6 -3.1 -0.9 -7.6 8th 2nd 6th (24'h) 18th 13ch 3lst Extreme Minimum -5.6 -16.8 -38.4 -42.9 -45.0 -44.3 -53.0 15eh 28th 13th l9u. 28th 13th 31st Mean Wind Speed (Knots) 12.6 11.8 6.6 3.3 14.2 10.0 1.5
Maximum Gust 210/47 (Direction/Knots) 16th Date
Number of Gales
Days of Snowfall •
Days of Adjacent Snow
Days of Snow Lying 0 -- -- 9
Cistern Pressure (mbs) Mean 0900
Mean (Three-hourly totals) (997.6)
Extreme 0900 Lowest 0900
Cloud Cover (Mean) tenths 4.3 4.6
Solar Radiation (Langleys) 19404 9741 2097 181 0 0 0
Net Flux Radiation (Ly.) +7086 +2216 +1963 -1591 -3638 -2914 -2153
Soil Flux Radiation (2")(Ly.) +606.4 +74.3 -461,6 -532.6 -322.5 -232.0 -811.6
Mean Relative Humidity 0900 38 (70 Soil Temperatures (°C) Mean: 8” Depth +3.0 Mean: 10* Denth -14.2 9 originating in high-level cirques along the south wall have advanced
at least three times since valley-cutting occurred.
Calkin and others (1970) established that the oldest Alpine
Glaciation (Alpine III) predated at least seven of the eight post-
valley-cutting Axial Glaciations recognized in Wright Valley. Fleck
(Appendix E) has obtained K-Ar dates from a volcanic cone in the
accumulation basin of one alpine glacier, Meserve Glacier, and from
volcanics included within lateral moraines of this glacier. I inter
pret these dates as indicating the Alpine III Glaciation in Wright
Valley occurred between 2.7 and 3.2 m.y. ago. The Alpine III
Glaciation in Taylor Valley occurred between 2.1 and 3.5 m.y. ago
(Denton and others, 1970). The youngest Alpine Glaciation (Alpine I)
post-dates at least seven of the eight Axial Glaciations and has a maximum age of 12,200 y. at Hobbs Glacier (Black and Bowser, 1969).
Black (personal communication) has now reported organic material
dating 30,000 y. B.P. at the same site. Dating of two volcanic cones near the bottom of Wright Valley by the K-Ar method indicates the valley-cutting stage occurred prior to 4.2 m.y. ago (Fleck, Appendix E).
If pedogenic rates could be obtained for locations proximal to an alpine glacier, then the stage of ahumic-soil development on one chronological sequence of Alpine Glaciation moraines could be used as an index of relative age for other soils in Wright Valley.
Meserve Glacier (Fig. 2) has been the object of intensive glaciological investigations (e.£., Carnein, 1967; Holdsworth, 1969;
Bull and Carnein, 1970; Holdsworth and Bull, 1970). Because glacio logical information was already available, and a permanent camp was 10 established, soil investigations were planned for the Meserve Glacier area. During the 1967-68 field season, K. R. Everett and I investigated the soils of the Meserve Glacier area (Everett and Behling,
1968, 1970; Everett, in press) with the support of the National Science
Foundation. We recognized that Alpine and Axial Glaciations did not occur in-phase, and another proposal to NSF was submitted by
P. E. Calkin and myself to study the glacial history and soils of
Wright Valley.
Preliminary results of the 1968-69 field season have been published (Behling and Calkin, 1969; Calkin and others, 1970). I returned to the field during the 1969-70 field season to collect soils on deposits representative of all glaciations in Wright Valley
(Behling and Calkin, 1970).
This report is the basis for using soil development as a method of relative dating of glaciations in Wright Valley, Antarctica. A detailed analysis of a very small area of the valley was necessary before increasing the scope of the method to include all of Wright
Valley and perhaps other ice-free areas of southern Victoria Land as well. Three soil pits were described and collected from each of the three moraines marginal to Meserve Glacier (Appendix B). These profiles represent the very small study area. CHAPTER II
WRIGHT VALLEY: PHYSICAL GEOGRAPHY, GEOLOGY, PEDOLOGY - PREVIOUS INVESTIGATIONS AUGMENTED BY THIS WORK
A. Physical Geography
Wright Valley is an asymmetrical glacial trough with bedrock benches at 1200 and 1500 m. Bull and others (1964) maintain that the benches were carved by glaciers broader, shallower, and higher than those which later cut the deeper U-form of the present valley. There is a prominent northward bend in the valley east of Bull Pass (Fig. 2) and a bedrock threshold (Fig. 3) determined by Bull (1960) from a single gravity survey across the Wilson Piedmont Glacier.
Elevations in the ranges north and south of Wright Valley are generally above 1500 to 1800 m with peaks more than 2400 m. Elevations increase to the west. Many high-level cirques are present in the
Asgard Range but only in the eastern half of the range do glaciers of significant size extend down the valley walls. High-level cirques in the Olympus Range are small and empty or contain only small quantities of stagnant ice.
At the western! end of the valley (Fig. 4), ice flowing eastward from the inland ice-sheet is channeled between nunataks and subglacial extensions of the Asgard and Olympus ranges. This ice flows over high rock-bastions flanking Mt. Fleming and coalesces to form the 10 km long, 4 km wide Wright Upper Glacier at an altitude of 1400 m (Bull
11 Wright Wilson 750 Lower Piedmont Glacier Glacier Elev. 5 0 0 ' L.Vanda m 250 ^ . 7 — S.L.
Figure 3. Longitudinal Profile of Wright Valley.
Vertical exaggeration about 14X. Note bedrock threshold beneath the Wilson Piedmont Glacier.
(After Bull, 1960) and others, 1962).
Wright Lower Glacier occupies the eastern end of the valley as a westward extension of Wilson Piedmont Glacier (Fig. 5). Maximum elevation of Wright Lower Glacier is about 500 m.
The ice-free floor of Wright Valley slopes westward for 30 km, from an elevation of approximately 400 m at the snout of Wright Lower
Glacier to about 50 m on the floor of Lake Vanda (Bull, 1960). A large shallow lake exists in front of Wright Lower Glacier and melt- water from Wright Lower Glacier and this lake initiates flow in the
Onyx River about the first week in December. By mid-December, Onyx
River is a continuous, meandering stream 30 km long flowing into
Lake Vanda; it ceases to flow during mid-February.
Onyx River first flows through and fills several shallow bedrock- based lakes before emptying into Lake Vanda. Lake Vanda occupies a closed bedrock basin and all water loss is by evaporation and sublimation. The present surface of Lake Vanda is at 123 m. Lake
Vanda is about 8.5 km long, 2,4 km wide, and up to 72 m deep. It is perennially ice-covered, with a range in ice thickness of 3 to 4 m, but in summer a moat up to 10 m wide forms along the shoreline.
West of Lake Vanda the valley separates into parallel branches, the North Fork and the South Fork, divided by the Dais. The floors of these smaller valleys are covered with thick ground moraine over a length of 8 km, and numerous undrained depressions prevent the small quantity of meltwater available from reaching Lake Vanda, The North and South Forks unite again to the west in an area of dolerite terrain cut by anastomosing incised channels known as the Labyrinth. The u
Figure 4. Wright Valley, looking west toward inland ice-plateau. (U.S. Navy aerial photograph).
Glaciers:
B Bartley D Denton G Goodspeed H Hart M Meserve T Taylor Glacier, Taylor Valley U Unnamed W Wright Upper
Physiographic features;
BP Bull Pass D Dais LM Loop end-moraine L Lake Vanda 0 Onyx River V Volcanic cone 15
Figure 5. Wright Valley, looking east toward Mount Erebus and Ross Island. (U.S. Navy aerial photograph).
Glaciers:
B Bartley C Clark D Denton G Goodspeed H Hart M Meserve U Unnamed W Wright Lower
Physiographic features; E Mount Erebus, Ross island L Loop end-moraine MS McMurdo Sound R Recessional moraines of Alpine II Glac iation, Unnamed Glacier. T Taylor Valley V Volcanic cones. 16 origin of this topography has been attributed to: (1) subglacial dissection (Cotton, 1966; and Gunn and Warren, 1962); (2) catastrophic erosion caused by either fluvial (Smith, 1965) or volcanic-induced fluvial (Warren, C, R., 1965) processes; and (3) differential salt weathering of the dolerite along a major joint pattern (Selby and
Wilson, 1971). This feature apparently extends westward beneath
Wright Upper Glacier.
B. Climate
Wright Valley is a cold desert and the climate is characterized by low annual temperature, low precipitation, and extremes in relative humidity. The mean annual air temperature at Vanda Station, Lake
Vanda (elevation 125 m), between December 1968 and July 1970 was
-20.0°C. In boreholes in Meserve Glacier at 480 m elevation, the temperature below 8 m averages -18°C (Holdsworth and Bull, 1970).
Bull and Carnein (1970) state that the mean annual precipitation in
-2 the valley probably is not greater than 5 g cm (all as snow) except on Wilson Piedmont Glacier.
Prior to 1968, only intermittent meteorological records were available for the ice-free valleys (see Bull, 1966; Carnein, 1967;
Bull and Carnein, 1970). During the 1968-69 austral summer, Vanda
Station was constructed on the southeast shore of Lake Vanda under the auspices of the New Zealand Antarctic Research Program. Year-round meteorological records are now available for at least this one site in these ice-free valleys of southern Victoria Land (Table 1).
During the first year of operation, the minimum temperature recorded at Vanda Station was -56.9°C on July 12, 1969 (Thomson, personal communication). Although strong westerly winds had been predicted during the winter months (Bull, 1966), Vanda Station experienced little wind; calm periods of up to three weeks were not uncommon. During calms, the temperature dropped steadily (reaching
-56.9°C during one prolonged calm) but rose sharply when wind arrived. Occasional winter warm spells of a few degrees below zero were observed during periods of wind (Thomson, personal communication).
The highest summer temperature reported by Bull (1966) for Lake Vanda is 8.3°C.
Surface wind directions in Wright Valley are controlled almost completely by the orientation of the valley. Katabatic winds originate on the ice plateau to the west or southwest of Wright Valley and descend over Wright Upper Glacier to the valley floor. The air is heated during 1200 m of descent by adiabatic compression and the specific humidity does not increase appreciably; thus the relative humidity of the westerly winds is low.
At Lake Vanda, Bull (1966) observed that on several occasions strong westerly winds were limited in vertical extent. Above 800 m on the valley walls, calm or light variable winds were experienced.
Similarly, easterly winds are also limited in vertical extent, with calm or light variable wind experienced above 1200 m on the valley walls. Although Bull (1966) reports that no westerly winds have been recorded in the eastern half of the valley, this author encountered westerly winds on several occasions 4 km west of Wright Lower Glacier.
The dominant wind direction for much of Wright Valley during the summer months is easterly, blowing in from McMurdo Sound. As air moves westward, it is cooled by adiabatic expansion in crossing the
Wilson Piedmont Glacier, elevation 600 m, and often becomes saturated.
Thus low cloud and associated precipitation is prevalent over the
Wilson Piedmont Glacier, Wright Lower Glacier, and the eastern end of the floor of Wright Valley.
During December 1958 and January 1959, dominant southeasterly winds were observed at Marble Point (Bull, 1966). With these winds, the mean temperature was about -2.7°C and the relative humidity about
757.. For this same period, easterly winds were observed at Lake Vanda and the mean temperature was -0.5°C. The mean relative humidity was 687..
Easterly winds are dominant in Wright Valley because of the strong tendency of Antarctic storm tracks to follow a path from west to east along the Oates Coast and across the mouth of the Ross Sea.
Storms then turn inland and circle around or over the Ross Ice Shelf and strike the mountains of southern Victoria Land from the eastern or seaward side.
Precipitation in Wright Valley has been determined from snow pit studies on glaciers because complete meteorological records for Vanda
Station have not yet been published. Precipitation was light at Vanda
Station during 1968-1969 as snow fell only 5 or 6 days in ten months and each fall was of less than one inch (Thomson, personal communication)•
At an elevation of 450 m on Wright Lower Glacier, about 12 km from the McMurdo Sound coast, the mean annual accumulation for three -2 years 1956-1959 was about 6 g cm (Bull, 1966). Above 1200 m in the -2 19 nev^ basin of the Meserve Glacier, accumulations of 3 to 7 g cm /yr _2 with a high of 16 g cm /yr were observed (Holdsworth, 1969). Dull and Carnein (1970) give the probable mean annual precipitation as not -2 greater than 5 g cm anywhere in the valley except on Wilson Piedmont
Glacier.
During the summer 1965-66,. snow fell at the Meserve Glacier site _2 (490 m) on 8 of 91 days, totaling about 1.2 g cm (Carnein, 1967).
Snowfall was generally associated with persistent stratus cloud from the northeast, and seven of the eight snowfalls occurred in conjunction with low-velocity northeasterly winds.
The precipitation effected by the easterlies in Wright Valley is usually restricted to elevations below 800 to 1000 m, and field observations suggest that Clark Valley and Wright Valley east of the
Loop Moraine have more days of summer precipitation than does Wright
Valley west of the Loop Moraine.
Carnein (1967) obtained meteorological information for
11 November 1965 to 13 February 1966 at two sites in the Meserve
Glacier area. Data from Moraine Station, on a flat part of the moraine 50 m east of the ice-cliff, at about 450 m elevation, and
Glacier Station, on the glacier surface, about 90 m west of the moraine site, at 490 m elevation, are given in Tables 2 and 3 and
Fig. 6.
Intermittent weather observations in the Meserve Glacier area were made during subsequent summer field seasons by Holdsworth (1966-
1967), Everett and Behling (1967-1968), McSaveney (1968-1969), and
Behling (1969-1970). The data have not been published. 20
TABLE 2, Percent Mean Cloud Amounts at Moraine Station, Meserve Glacier, Summer 1965-1966.
Time Mean Estimated Month 0700 1300 1900 Total Clouds Low Cloud
11-30 Nov. 60 58 64 61 35
Dec. 47 52 54 51 24
Jan. 43 44 56 48 24
5-13 Feb. 85 86 95 89 70
Carnein (1967) 21
TABLE 3 . Monthly mean and extreme temperatures (°C) at Base and Glacier Stations (Stevenson Screens).
November December January February 1965* 1965 1966 1966**
Mean Base -8.7 -2.8 -4.9 -6.1 Monthly Glacier -3.0 -5.8 -6.7
-0.6 +5.3 +1.5 -0.3 Base 29 Nov. 22 Dec. 30 Jan. 7 Feb. Maxima +3.7 +1.5 -1.1 Glacier 22 Dec. 30 Jan. 7 Feb.
-17.8 -10.8 -11.4 -12.7 Base 16 Nov. 3 Dec. 18 Jan. 5 Feb. Minima
-11.3 -12.2 -13.3 Glacier 3 Dec. 18 Jan. 5 Feb. Mean Base -4.7 +1.1 -0.9 -2.2 Monthly Glacier -0.1 -2.3 -2.6 Maximum Mean Base -12.0 -5.7 -7.5 -8.5 Monthly Glacier -6.0 -8.3 -9.2 Minimum
*Record for November 11-30 at Base Station. **Record for February 1-13 at both stations. NOTE: Minimum winter temperature for year 1966: -4l°C (Base Station)
Carnein (1967) SOI RADIATION FLUX 09 04 03 az
10 30.1 20 29 30 (l 9 INCOMING RADIATION '1200 HOO coo 900 BOO TOO 600 900
MELT
rfrtf-ff- 20 I 2 0 M l
TEMPERATURE *10
MINIMUM
30120 •20
100-1 MESERVE GLACIER, ANTARCTICA •400 >0- u - if c & S C STATION ■ 90 •-•^O AO CR STATON •0- ■60 TO • TO CO- -CO 90- ■SO -40
20 10- TTTT 20 20 29
Figure 6. Meteorological Parameters at Base (Moraine) and Glacier Stations, Meserve Glacier, November 1965- February 1966.
Carnein (1967) 23 C. Bedrock Geology
The bedrock geology of Wright Valley has been studied in detail by several investigators (£•£•t McKelvey and Webb, 1962; Webb, 1963; and
Smithson and others, 1968, 1969). The geologic map (Fig. 7) and the bedrock chronology (Table 4) presented here are modified after McKelvey and Webb (1962).
In Wright Valley, the basement complex consists of Precambrian to
Lower Paleozoic metasediments, granite-gneiss, granite and associated dikes and veins. It is unconformably overlain by the Beacon Group of sedimentary rocks on upper slopes, and both the basement complex and
Beacon rocks have been intruded by dikes and sills of diabase.
Several small volcanic cones are present along the south wall of the valley and in the Meserve Glacier cirque basin (Fig. 4).
Metasediments of the Asgard Formation in Wright Valley belong to the Skelton Group of folded metasediments exposed throughout much of southern Victoria Land. They are the oldest rocks of Wright Valley and consist of more than 5000 m of marbles, homfels, and schists
(Gunn and Warren, 1962), The type rocks of the Asgard Formation extend from west of Mt. Loke to Mt. Valkyrie in the Asgard Range
(Fig. 7), and thus crop out east and west of the Meserve Glacier tongue.
Smithson and others (1968) characterize a typical sequence of metasedimentary rocks as being composed of marble (commonly graphitic), diopside granofels, plagioclase granofels, tremolite schist, quartzo- feldspathic gneiss, amphibolite, and some pelitic schist.
Three fold systems are present in the raetamorphic rocks within
Wright Valley (Smithson and others, 1969). Emplacement of Olympus "TT
• • • ♦
•• • • • l*ll • •
• •• •,*, V//J
7
AiUtiUMZl
Figure 7 Bedrock Geology of Wright Valley. Diagrammatic representation of Vanda Lamprophyre, Theseus Granodiorite, and Loke Microdiorite. Bartley Glacier (B), Denton Glacier (D), Goodspeed Glacier (G), Hart Glacier (H). (After McKelvey and Webb, 1962.) f//
7 r 3 0 - i mm IB □ E 3 »•*« crj.it* Glacial Bapasit* I^ M Thasaaa Graaatfiarita Farrar Dalarita h.i-.l laka llcratfiarita I Baacaa Graap |«v*l B ijt Graaita
V'A Vaada Laa^rapkyrt|111 !l Pliapaa Graaita-Gaain
O ^ A i i a r r i Fa. AUAIdllifil nile* ght Valley, esentation of Vanda Lamprophyre, Theseus Granodiorite, and , Bartley Glacier (B), Denton Glacier (D), Goodspeed Glacier (G),
hO (After McKelvey and Webb, 1962.) 25 Granite-gneiss and regional metamorphism accompanied the folding, and granitic dikes were emplaced between formation of the second and the
third fold systems. Smithson and others (1969) are of the opinion
that the Larsen Granodiorite (Dais Granite of McKelvey and Webb, 1962)
is synkinematic with respect to the third fold system.
Deutsch and GrBgler (1966) obtained an age of 610 m.y. for zircons from the Olympus Granite-gneiss by the U-Pb method. Rubidium-strontium analyses of Olympus Granite-gneiss, Dais Granite, and Vida Granite indicate an age of 490 + 14 m.y. for all three units (Jones and Faure,
1969). Jones and Faure (1969) concluded that these igneous and meta- morphic rocks either crystallized 490 + 14 m.y. ago or that they were extensively recrystallized and isotopically homogenized at this time.
Loke Microdiorite intrudes Olympus Granite-gneiss at Mt. Loke and to the east of Mt. Theseus (Fig. 7). Dais Granite (Larsen Grano diorite of Smithson and others, 1969), Olympus Granite-gneiss, and
Loke Microdiorite are intruded by dikes of Theseus Granodiorite. These
four formations are termed the Wright Intrusives by McKelvey and
Webb (1962).
Basement intrusives younger than the Theseus Granodiorite, the
Victoria Intrusives of McKelvey and Webb (1962), include the Vida
Granite and Vanda Lamprophyre and Porphyry. Smithson and others (1968) consider the Vida Granite a quartz monzonite which is a cross-cutting postkinematic intrusive. Vanda Lamprophyre and Porphyry dikes intrude all other rocks of the basement complex. Jones and Faure (1968) dated these rocks at 470 m.y, old by the Rb-Sr method.
An erosional episode followed the intrusion of the Vanda TABLE 4. Bedrock Chronology of Wright Valley. (Modified after McKelvey and Webb, 1962)
AGE GROUP FORMATION
Quaternary McMurdo Volcanics Upper Tertiary
Victoria Orogeny
Cretaceous Ferrar Dolerites Jurassic
Mid-Mesozoic (Jurassic) Beacon (Sandstone) Mid-Paleozoic (Devonian)
Kukri Peneplain
>■» • Lower Paleozoic Victoria Intrusives Vanda Lamprophyre and Porphyry e >. a • Vida Granite to 6 o Wright Intrusives Theseus Granodiorite tJ o o o Loke Microdiorite m w i Dais Granite (Larsen Granodiorite) to o o tn Upper Cambrian Olympus Granite-Gneiss efi *
Cambrian c Skelton Group Precambrian Aseard Formation Lamprophyre and Porphyry dikes. The resulting erosion surface,
recognizable throughout the Transantarctic Mountains and elsewhere in
East Antarctica, was described by Ferrar (1907) and Debenham (1921)
from the Kukri Hills south of Taylor Valley and subsequently named the
Kukri Peneplain by Gunn and Warren (1962).
Sediments of the Beacon Gro,up (Beacon Sandstone of McKelvey and
Webb, 1962) lie unconformably on the basement complex in the western
Olympus and Asgard ranges (Fig. 7). The Beacon Group ranges from
Lower Devonian (Boucot and others, 1963) to at least Upper Jurassic
(Plumstead, 1962), and has a maximum thickness of more than 1550 m in
the region of Wright and Taylor valleys (Webb, 1963). Subgreywacke,
arkose, and orthoquartzite compose the major sedimentary rock types of
the Beacon Group. Shale and thin siltstone beds are present at
Mt. Odin (Fig. 7). In the eastern part of Wright Valley, erosion has removed most of the Beacon Group sediments, but remnants are preserved
locally beneath a dolerite sill.
Ferrar Dolerite sills and dikes of Jurassic age Intrude rocks of
the Beacon Group and the basement complex (McDougall, 1963). Individual
sheets of diabase attain thicknesses up to 460 m with total thicknesses up to 1550 m (Hamilton and Hayes, 1963). Diabase sills commonly occur at the unconformity between the basement complex and the Beacon Group.
Regional block faulting (Victoria Orogeny) occurred during Upper
Tertiary and Quaternary time (Gunn and Warren, 1962). This uplift gave rise to the present mountains of Victoria Land and caused the peneplain surface with its overlying Beacon Group and Ferrar Dolerite sills to dip gently (6 to 10°) to the west and southwest. 28 Harrington (1969) has reviewed the evidence for the Paleocene or
Eocene fossil biota first found in a small erratic from Minna Bluff and considers it very unlikely that they have been derived from the west side of the Transantarctic Mountains. Rather, he considers it probable that a Cretaceous and Tertiary sedimentary sequence of the
New Zealand type is widespread ip Marie Byrd Land and possibly also under the floor of the Ross Sea. Very little is yet known about the age and tectonic history of the Ross Sea.
Late Tertiary-Quaternary basic volcanics (McMurdo Volcanics) are the next youngest formation recognized in southern Victoria Land.
These are located mainly on Ross Island, but cones are abundant in
Taylor Valley and occur along the south wall of Wright Valley above the Loop Moraine, in the cirque basin of the Meserve Glacier (Fig, 4), and on the west side of Bartley Glacier. Potassium-argon dates as old as 27.3 m.y. have been obtained for McMurdo Volcanics in the vicinity of Mount Early (V. H. Minshew, in preparation), but the oldest basalts from Wright and Taylor valleys are less than 4 m.y. (K-Ar dates reported by Armstrong and others, 1968; Denton and Armstrong, 1968; and Fleck, Appendix E). Mount Erebus on Ross Island (Fig. 1) is the only active volcano in the immediate vicinity of Wright Valley.
Most of the bedrock types in Wright Valley crop out in the Meserve
Glacier area. From the pronounced shoulder of the Asgard Range at about 1130 m to the valley bottom, the Meserve Glacier passes over the type rocks of the Asgard Formation (McKelvey and Webb, 1962). The aretes and peaks of the Asgard Range above the Meserve Glacier are composed of Ferrar Dolerite, but no Beacon Group sediments have been 29 recognized in situ on the south wall, east of Bartley Glacier (Fig, 7),
Two volcanic cones occur within the accumulation basin of the
Meserve Glacier (Fig. 4). Other cones may be present beneath the ice
or beneath the morainal debris on the west side of the Meserve Glacier.
D. Glacial Geology
(1.) Introduction
An introduction to the chronology of glacial events in the
McMurdo Sound region is essential in order to establish the
chronological sequence of surficial deposits in Wright Valley,
especially near Meserve Glacier.
Glacial events in Wright Valley were first described by Nichols
(1961a) and Bull and others (1962) (Table 5). They were hampered in
their investigations by a lack of absolute dates, but the correlation
of glacial events with K-Ar dates from associated volcanics elsewhere
in southern Victoria Land by Calkin and others (1970) did not
significantly change the basic chronology. It has now been shown,
however, that multiple glaciations by alpine glaciers provides a means
of partially correlating glacial events at opposite ends of Wright
Valley which are not stratigraphically interrelated (Fig. 8). It is
again called to the reader's attention that in this report, glaciations
resulting from ice advance following the main axis of the valley are
called axial glaciations, and that glaciations resulting from ice
advance from cirques in the Asgard Range are called alpine glaciations.
Bull and others (1962) recognized that major glaciations in
Wright and Victoria valleys were responsible for cutting benches, accordant cirques, and floors, at elevations up to 1500 m, across the TABLE 5. Glaciations in Southern Victoria Land*
McMurdo Sound Region Wright Valley
(Pewe, 1960) (Bull and others, 1962) (Nichols, 1961a) Glaciations from the west Glaciations from the east young
Koettlitz Glaciation Fourth Glaciation Trilogy Glaciation
Fryxell Glaciation Third Glaciation Loop Glaciation
Taylor Glaciation Second Glaciation Pecten Glaciation
McMurdo Glaciation First Glaciation Unnamed Glaciation* old
*Glaciation from the west, the "valley- cutting" stage. entire width of the present-day ice-free area. They called it the
"First Glaciation" and correlated it with the McMurdo Glaciation of
P^we (1960) in Taylor Valley. Nichols (1961a) studied the glaciations in the eastern end of Wright Valley and termed the glaciation which carved the bedrock basin of Lake Vanda as "pre-Pecten". None of these authors, however, suggested that the oldest recognizable glaciation in 1 * Wright or Victoria valleys was pre-Quaternary in age. A K-Ar date of
3.7 m.y. for volcanic cones in Wright Valley provided the first absolute minimum-date for the valley-cutting by outlet glaciers in southern Victoria Land (Nichols, in press; Fleck, Appendix E; Denton and others, 1970),
Continued investigations have shown that three major glacier systems have affected the ice-free valleys in the McMurdo Sound region eastward ice-flow from the East Antarctic Ice Sheet over col divides in the Transantarctic Mountains; westward ice-flow from an expanded and grounded Ross Ice Shelf; and valley-sided glacier ice-flow from cirques in the Transantarctic Mountain ranges.
Throughout this report, the term "glaciation" is not restricted to a climatic episode. According to the definition of the American
Commission on Stratigraphic Nomenclature (1961, Articles 39 and AO, p. 660): "A glaciation was a climatic episode during which extensive glaciers developed, attained a maximum extent, and receded." A glaciation herein defined is an event in which glaciers advanced
(perhaps only 10 m in the case of valley-sided glaciers and a few tens of meters for axial-ice advances), attained a maximum extent, and retreated. This definition allows for the description of axial and Figure 8. Extent and Tentative Correlation of Glaciations in Wright Valley, Antarctica. (After Calkin and others, 1970)
C lirk
S km
r~-
Meserve Glacier
WRIGHT UPPER I 6,000-9,500 y. — ALPINE I — WRIGHT LOWER 12,200 y 34,800 y. or older
WRIGHT UPPER II— —TRILOGY — ALPINE II— WRIGHT UPPER III— 0.5 m.y. —LOOP -— MUDFLOWS AND FANS— 800,000 y. —PECTEN 2,1 m.y. 1.2 m.y. 2.1 m.y, -— ALPINE III— WRIGHT UPPER IV— 3.5 m.y. 10 3.7 m.y. to Valley-cutting Episode(s)-- alpine glaciation relationships which did not necessarily react
synchronously with climatic changes. The complex relationships between
axial and alpine glaciations have been described by Denton and others
(1969, 1970) in Taylor Valley and by Calkin and others (1970) in
Wright Valley. Correlation of recognized axial and alpine glaciations
in these valleys are presented in Table 6 and Fig. 8. A brief synopsis
of all glaciations in Wright Valley follows,
(2.) Glaciations from the West: Wright Upper Glaciations
The accumulation of a thick ice-sheet over East Antarctica
flooded the now ice-free area of southern Victoria Land with outlet glaciers. Multiple erosion surfaces led Bull and others (1964) to suggest that more than one glaciation occurred as ice from the inland
ice-sheet flowed through Wright Valley to McMurdo Sound. Glacial erosion was intense and cirques in the Asgard and Olympus ranges were truncated as the thick wet-based ice sculptured the asymmetrical trough-shaped valley with its high bedrock threshold and deeper head ward portions. Deposits from these glaciations in Wright Valley have apparently been reworked or buried by subsequent glaciations, but a record of glaciations representative of the valley-cutting stage may be recorded further south in the Transantarctic Mountains (Oliver,
1964a; Mercer, 1968a, 1970).
Potassium-argon dates of small basaltic cones on the floor of
Wright Valley west of Bartley Glacier and along the south wall east of
Goodspeed Glacier give a minimum age of about 4 x 10^ years for the valley-cutting by outlet glaciers (Denton and others, 1970; Nichols, in press; Fleck, Appendix E). Outlet glaciers from the inland ice- 34 TABLE 6. Correlation Chart and Chronology of Glacial Events in the McMurdo Sound Region. (After Denton and others, 1970)
TAYLOR GLACIATIONS (Ice sheet in East ROSS SEA GLACIATIONS ALPINE GLACIATIONS Antarctica west of (Ross Ice Shelf) Taylor and Wright Valleys)______
TAYLOR I -49490 y. B.P. ALPINE I
12,200 y. B.P.
ROSS I
34,800 y. B.P. ALPINE II to 2.1 to /v0.4 m.y. >49,000 y. B.P. K/Ar dates; Walcott Glacier area. ROSS II TAYLOR II ROSS III
ROSS IV 3.1 to 1.2 m.y. TAYLOR III K/Ar dates; Walcott 1.6 to 2.1 m.y. Glacier area. K/Ar dates; Taylor Valley.
2.1 m.y.; K/Ar dates; Taylor Valley.
TAYLOR IV ALPINE III 2,7 to 3.5 m.y. 3.5 m.y.; K/Ar dates; K/Ar dates; Taylor Taylor Valley. Valley. 3.7 m.y., Wright Valley.
TAYLOR(S) V 35 sheet have not flowed through the valley to the sea since this time.
Glaciers advancing into the valley from the west since the valley-
cutting period have apparently been frozen to the underlying bed,
either because they were thinner or because the mean annual air
temperature was lower than at the valley-cutting stage (Ugolini and
Bull, 1965). Thick deposits of drift in the North and South Forks of
the valley and along the valley floor to the eastern end of Lake Vanda
are evidence of these Wright Upper Glaciations (Fig. 8).
Wright Upper Glaciation XV was the most extensive of these ice
invasions from the west and extended 23 km east of the present terminus,
to the east end of the depression now occupied by Lake Vanda. If this
advance is correlative with Taylor Glaciation IV as suggested by
Calkin and others (1970), it occurred between two and three million
years ago. Wright Upper Glaciation III was less extensive than Wright
Upper Glaciation IV (Fig. 8) and left thick drift exhibiting stagnant-
ice features in the South Fork of Wright Valley. If this advance did
not occur before Taylor Glaciation III, this glaciation has a maximum
age of 1.6 m.y. (Denton and others, 1970).
A much more recent advance, Wright Upper Glaciation II, extended
only 2 km east of the present glacier terminus. The terminal position
of this advance is marked by a line of very large cavernously weathered boulders of Beacon Group sandstone, and of fine-grained diabase blocks
that still retain their columnar form (Calkin and others, 1970).
Wright Upper Glaciation I is defined by the present position of Wright
Upper Glacier as it is advancing over weathered deposits of Wright
Upper Glaciation II (Wilson, letter to C. Bull, 1968). 36
(3.) Glaciations from the East
GLacial invasions from the Ross Sea and McMurdo Sound areas have in the past extended 26 to 30 km west from the present Wright Lower
Glacier terminus, but at present Wright Lower Glacier is a relatively inactive lobe of Wilson Piedmont Glacier extending only a few kilo meters into Wright Valley (Fig. 4). . Terminology proposed by Nichols
(1961, and in press) is used here to describe glaciations from the east. The earliest and most extensive westward advance recognized in
Wright Valley is the Pecten Glaciation. Ice extended farthest (26 to
30 km) into Wright Valley from the coast during this advance and carried pecten shells and volcanic erratics in addition to debris from the bottom of McMurdo Sound. The shells occur in outwash which has been covered by mudflows from Bull Pass. Radium-uranium measurements show that the shells are more than 200,000 years old and possibly more than 800,000 years old (Nichols, in press).
The maximum extent of the second westward advance, the Loop
Glaciation, is 18 km west of the present Wright Lower Glacier and
7 km west of the prominent looped end-moraine that Nichols (1961a) described as the type deposit. Prominent lateral moraines lie along the north and south walls, inside the 75 m high looped end-moraine, but the maximum extent of the Loop Glaciation is represented only by small nested kame terraces a few tens of meters above the valley floor north of the Onyx River.
The third glaciation from the area now occupied by the Ross Sea is known as the Trilogy Glaciation in Wright Valley and is marked by an ice-cored terminal moraine 9 km west of the present Wright Lower 37 Glacier terminus. Deposits resulting from this glaciation are distinct
from the older Loop and Pecten deposits in that they exhibit marked stagnant-ice features and include numerous ice-cored moraines. The
abundance of volcanic erratics in the Trilogy deposits suggests that
this ice advance was from an ice-sheet grounded in McMurdo Sound.
Wright Lower Glaciation occurred between 9500 and 34,800 years % ago and perhaps extended 2 km westward from the present ice-front position (Calkin and others, 1970), An ice-cored moraine at this position was originally considered the youngest Trilogy deposit (the
"Anomalous" moraine of Nichols, 1961a), but it may represent the terminal position of the last westward glaciation in Wright Valley.
I have studied the weathering of the Trilogy deposits in great detail and found that from the oldest to youngest Trilogy deposits, there is only a slight color change and a gradual decrease in depth to the ice-cemented layer or to ice-core. No significant break in degree of surface weathering occurs on Trilogy deposits, from the
"Anomalous" moraine to a discontinuous series of ice-cored moraines
10 to 50 m from the present terminus. I propose, therefore, that
the Wright Lower Glaciation extended no more than several tens of meters westward from the present ice-front position, perhaps due to expansion of the Wilson Piedmont Glacier. There is no evidence that during this time Wright Lower Glacier was an extension of a grounded ice-sheet in McMurdo Sound.
(4.) Advances of Valley-sided Glaciers
The advances northward of the alpine glaciers in the Asgard Range appear to have been out of phase with advances of the westward-moving and possibly the eastward-moving axial glaciers. This is shown by erratics deposited on portions of the Alpine III lateral moraines by
Pecten and Loop ice and by the erosion or burial of Pecten and Loop deposits by the Alpine II Glaciation. Accumulation rates for the
alpine glaciers would probably be reduced by the presence of an ice-
sheet covering McMurdo Sound and the western part of the Ross Sea, as
easterly storm tracks cross the Ross Sea and provide most of the nourishment for the alpine glaciers. The oldest recognizable advance
of the alpine glaciers, Alpine III Glaciation, has been correlated
with deposits in Taylor Valley that are between 2,2 and 3.6 m.y. old
(Calkin and others, 1970). In Wright Valley, deposits of Alpine III
Glaciation remain around Goodspeed, Hart, Meserve, and Bartley glaciers,
and around the unnamed glacier west of Bartley Glacier. Where
preserved, end moraines of this Alpine III Glaciation reach to the
bottom of the valley, indicating that the glacier flowing westward
along the main axis of the valley was absent at the time of formation
of Alpine III moraines. However, Alpine III deposits of these five
valley-sided glaciers are crossed and in part covered both by moraines
of the Pecten Glaciation and, with the possible exception of the
Alpine III deposits of the unnamed glacier west of Bartley Glacier, by
deposits of the Loop Glaciation. The age relationship of Alpine III
to the Wright Upper IV is not well established.
Calkin and others (1970) suggest that following the Alpine III
Glaciation but preceding the Alpine II Glaciation, a moister climate
prevailed which was marked by construction of mudflows and alluvial
fans. These conditions may have produced an alpine glacier advance 39 but no deposits of such an event have been definitely recognized.
Looped end-moraines of the unnamed glacier west of Bartley Glacier and the lateral moraine (Ila, Fig. 9) on the east side of Meserve Glacier may be evidence of a glaciation during this interval.
Moraines of the Alpine II Glaciation cross moraines of the Loop and Pecten Glaciations. Multiple lateral moraines indicate that ice margins fluctuated often during this glaciation. From drift relationships in front of Clark and Denton Glaciers, the Alpine II
Glaciation appears to post-date the Trilogy Glaciation. The age of the Alpine II Glaciation is not known, but estimates by weathering comparisons are that it is about 500,000 years old (Calkin and others,
1970). Denton and others (1970) have dated volcanics in the Walcott
Glacier area at about 0.4 m.y. that are older than the middle
(Alpine II) glaciation at that location.
Since the Trilogy Glaciation, all of the alpine glaciers have shown a slight advance and subsequent minor retreat. Ice-cored moraines of this Alpine I Glaciation are 5 to 50 m from the present ice-margins. Algae incorporated in the present basal moraine of Hobbs
Glacier, 70 km to the southeast, have been dated by Black and Bowser
(1968) at 12,000 years B.P., and if correlative with the Alpine I
Glaciation in Wright Valley, the date may provide a minimum age for this glaciation.
(5.) Fossil Record in Quaternary Marine Deposits
Locations and faunal assumblages of fossiliferous Quaternary marine deposits in the McMurdo Sound region have been reviewed by
Speden (1962) and referenced by Harrington (1969). Speden (1962) 40
Meserve G|.
WVMC 6
Pecten WVM 24 x
Figure 9. Diagrammatic Relationships between Axial and Alpine Glaciation Deposits, and Pit Sites, Meserve Glacier, Wright Valley. 41 recognized two formations, the Scallop Hill Formation and the Taylor
Formation. The Scallop Hill Formation consists of cemented tuffacoous
sandstones, grits, and conglomerates containing the extinct thick-
shelled lamellibranch Chlamys (Zygochlamys) anderssoni (Hennig). This
formation frequently occurs 120 to 600 m above sea level. The
formation has been glaciated and Speden (1962) suggests an early
Pleistocene interglacial age for the Scallop Hill Formation.
The Taylor Formation consists of frozen but unconsolidated marine
sediments containing the Recent thin-shelled Adamussium colbecki
(Smith), These sediments occur up to approximately 60 m but most
localities are below 20 m. The deposits have not been glaciated at
the type locality near the south side of the mouth of Taylor Valley.
Fossils collected by Nichols (1961a) from the "Pecten Moraine" have been named as a new species, Chlamys (Zygochlamys) tuftsensis, by Turner (1967). The new species of fossil Chlamys has been described
only from the glacio-fluvial gravels in the deposits below Bull Pass.
Turner (1967) gave an age of early to middle Pleistocene for the new
species and considered the fossils to be possibly younger than those
of the Scallop Hill Formation. However, Turner states that the
fossils from "Pecten Moraine" are definitely older than the Recent
lamellibranchs in the Taylor Formation. New radium-uranium dating suggests that the shells in Wright Valley are more than 200,000 years old and possibly more than 800,000 years old (Nichols, in press).
Bull (personal communication) has collected two pecten shell
fragments several hundred meters above the type locality described by Nichols, along the north side of Wright Valley. One fragment was 42 found at an elevation of 600 to 800 m near the top of the west side of the bedrock gorge leading from Bull Pass, and the other fragment was found 1 to 3 km east along the north wall, at about the same elevation. These locations are significantly higher than would be expected if the terminal position of the Pecten Glaciation was no further west than Bull Pass, but Behling (1970) has found evidence suggesting that the Pecten Glaciation extended nearly 4 km further west than the "Pecten Moraine", The mechanics of shell deposition at these two higher sites and the ultimate source of all pecten shells in
Wright Valley remain undetermined. No fossiliferous marine deposits have been reported either in Wright Valley or along the coast south of
Wright Valley to the type location of the Taylor Formation.
(6.) Quaternary Climate Changes
Pewe' (1966) considered that the best record of Quaternary climatic change in Antarctica comes from the history of multiple glaciation in the areas now ice-free. Methods employed in determining climatic changes in the McMurdo Sound region have included the intrepretation of the wide variety of interglacial features (Thomas, 1959, 1960;
Hough, 1960; Calkin, 1964; Wilson, 1964; Nichols, 1965; Berg and Black,
1966; Pewd", 1966; Mercer, 1968b; Denton and others, 1970), natural thermoluminescence (Zeller and Pearn, 1960; Ronca, 1964; Ronca and
Zeller, 1965), oxygen- and hydrogen-isotope analyses of ice samples from the Byrd Core (Epstein and others, 1970), and the fossil record in marine sediments marginal to the continent (Bandy and Casey, 1969,
1970). Because the time scale to be considered covers the Late
Tertiary to Recent, a logarithmic representation of climatic changes 43 is presented in Fig. 10.
Meserve Glacier at present is in equilibrium or has a slightly
positive mass balance (Bull and Carnein, 1970). Unless dry calving
from the cliffs, evaporation, or sublimation increases during
glaciations, a positive mass balance of Meserve Glacier would be
maintained by increased snow accumulation. It is reasonable to assume
that areas marginal to the expanding ice-tongue would also be subjected
to a wetter climate during periods of increased precipitation, although
total water equivalent supplied to debris marginal to the ice-tongue need not have corresponded to the annual positive accumulation-balance.
Surficial deposits in the vicinity of Meserve Glacier have probably
been subjected to at least four climatic variations since the Alpine II
Glaciation, 2.1 to 3.5 m.y. ago (Table 7).
Holdsworth (1969) concluded that debris, now seen in the lower 3 4 tongue area, could have been in transit 10 to 10 years. Alpine I
lateral moraines are thin, discontinuous, and ice-cored, and they 3 4 could have been formed in 10 to 10 years despite the small basal
load carried by the glacier at the elevations where they have been
formed. Construction of the Alpine II deposits, however, under similar 4 5 ice-flow conditions, may have taken at least 10 to 10 years.
E. Soils in Wright Valley
(1.) Introduction and Classification
Soils of the polar regions are divided into three zonal great soil
groups, Arctic Brown, Polar Desert, and Cold Desert (Tedrow, 1968), with Arctic Brown and Polar Desert soils predominating in north polar regions and Cold Desert soils apparently existing only in south polar 44
* 1 1 *!..?! •'!* ...... 'I* ..... ll* ite m PIEISTQCINI wise...... 1 ■ III.. j IUCL. , |NTP1ITNER. i QTIIIII wiitim i CDll
I. I I. I * . II I. I I. II hil.l WU. II I h Wl. Trllao 1 . 1- 1. II I -H«L-.c?UL *ruiV a a a W * » •( •I IT III IT II 1. Ill Ac. I. II *. I I. lilutt Cl. Mil ■ Callt r__ t '| Na Ica-i■rillaV hn< Imi J SaCiaiaala I A. taliail | laa la Tartar •ail lltir lta> |-- 1 WU. Cl. Valla) liaiaitat aMia. I(a WII. Ill
Figure 10. Postulated Climatic Changes in Antarctica During the Past 5 x 10^ Years,
Key: Gl. Glaciations A. Alpine Glaciations WU. Wright Upper Glaciations WL. Wright Lower Glaciations T. Taylor Glaciation R. Ross Sea Glaciation RY. Reedy Glaciation B. Beardmore Glaciation H. Horlick Glaciation S. Sirius Glaciation
I.G. Interglacial TEMP. Temperature TROP. Tropical c. Cold w. Warm Temp. Temperate i 1
44
l a i n IP. m u c iy*» r i n t u lost
I c»ti [t Im p. "cm;.. inij, e. Mia. la ia t
I . Ill Ma I .C l. Ka I. Gl. MU. II MU. Ill laaa Paclaa I— Mai
la Cl. . Ill III
CL. QaU.f____ Ha Ict.rallii S«4i*«ftti
tMla. t(a MU. Ill
imatic Changes in Antarctica he Past 5 x 10^ Years, iations ne Glaciations ht Upper Glaciations ht Lower Glaciations or Glaciation Sea Glaciation y Glaciation dmore Glaciation ick Glaciation us Glaciation rglacial erature ical erate 45
Figure 10. Postulated Climatic Changes in Antarctica During the Past 5 x 10^ Years. (Continued).
References: , ,
A Harland (1964).
B Ericson (1964); Goldthwait (1966); Hays and Updyke (1967). Glaciations in North America and New Zealand.
C Minshew (in preparation).
D Bandy and Casey (1969).
E Goodell and others (1968).
F Hays (1970).
G Denton and others (1969, 1970).
H Calkin and others (1970).
I Epstein and others (1970).
J Ronca (1964); Ronca and Zeller (1965).
K Mercer (1968b, 1969, 1970).
L Dort (1970).
M Berg and Black (1966).
N Thomas (1959, 1960) and Nichols (1965) after Hough (1950).
0 Wilson (1964, 1970).
P Roberts (1965).
Q Bell (1966). 46
TABLE 7. Possible Climatic Changes in the Vicinity of Meserve Glacier during the past four million years, based upon weather ing analyses in this report and paleo-climate data from Fig. 10,
Occurrence Estimated Years. B.P. Possible Duration
Alpine I 103 to 104 m x 10 years
4 5 Alpine II about 10 minimum 10 to 10 years
Mudflows and 4 5 Alluvial Fans about 10 10 to 10 years Alpine Ila ?
4 6 Alpine III 2.1 x lo!? to 10 to 10 years 3.5 x 10° 47 regions, with the possible exception of the high mountain country in
Tien Shan (Glazovskaia, 1952) and regions of Peary Land, northern
Greenland.
Soils in southern hemisphere polar regions, in Antarctica and the
sub-Antarctic Islands, were studied very little prior to 1956. The
highly alkaline nature of these soils was first reported by Jensen
(1916) and many authors (e.£■» Markov, 1956; Glazovskaia, 1958;
McCraw, 1960; Claridge, 1965; Tedrow and Ugolini, 1966; and Linkletter,
1971) have since conducted pedologic studies in Antarctica. The nomenclature of Tedrow and Ugolini (1966) (Table 8) will be used
throughout this report when describing soils in Wright Valley.
In the ice-free regions of Antarctica, soils characteristically
have a very small amount of organic matter, and physical weathering
predominates over chemical weathering. Temperatures are low, usually
averaging less than 0°C in the warmest months, and precipitation is -2 low, about 5 g cm annually. An ice-cemented substrate is common as
are salt efflorescences, and soils tend to be ahumic but not every where abiotic.
(2.) Organic Constituents of Antarctic Soils
Vegetation of the Antarctic consists almost entirely of lichens, algae, mosses, and fungi (Rudolph, 1966), and the indigenous fauna consists of flies, sucking and biting lice, mites, springtails, and
ticks (Boyd and Boyd, 1963). Reviews of the early botanical
investigations and the microbiology in Antarctica have been presented by Rudolph (1966) and Sieberth (1965) respectively.
Bacteria are present in some Antarctic soils and are perhaps the 48 Table 8, Soils of the Cold Desert
1.) Ahumlc soils
Common to the dry valleys (sic), mantling rolling valleys and talus slopes. Organic matter almost nonexistent, soluble salt content and pH rather high throughout.
2.) Evaporite soils
Common in the dry valleys (sic), in depressions, basins, and low, flat drainage ways. No out standing morphologic features except for concentration of salt.
3.) Protoranker soils
A tentative term for those places where plants (moss and algal material) colonize the mineral substrate. More common in the northern Antarctic Peninsula. The term is an approximation after the ranker soil (Kubiena, 1953).
4.) Omithogenic soils
Organic soil of penguin rookeries of Antarctica, as proposed by Syroechkovsky (1959). Organic matter has the characteristic of low-rank guano. Should probably be redefined to include organic soils resulting from any faunal occupation.
5.) Regosols
Areas of fluvial, recent glacial, and other deposits. No apparent genetic features. Chemically, a saline soil.
6.) Lithosols
On valley walls and nunataks; comprised of bedrock with almost no loose surficial mantle. Of the six soils, perhaps the most extensive on the continent. The predominant soil of the Asgard and Olympus ranges and the north wall of Wright Valley.
after Tedrow and Ugolini, 1966 49 most important organic constituent of the ahumic soils in the ice-free valleys of southern Victoria Land, At one soil site in McKelvey
Valley, Cameron (1967) found aerobic, anaerobic, and microaerophilie bacteria or yeasts, but abundance was low. The pH, electrical
conductivity, and rn situ Eh values indicated that the soil environment was restrictive to some microorganisms but favorable for salt-tolerant organisms.
Cameron and others (1968a) outline the ecological factors determining abundance and diversity of microorganisms in the ice-free valleys. Unfavorable environmental conditions, such as east-west valley orientation, south-facing slopes, low solar-radiation flux, high southerly winds, low humidities, short duration of available water, and salt soils, restricted the existence and activity of microorganisms.
Under the least favorable conditions, either no microorganisms or only a single population of heterotrophic, aerobic, nonpigmented bacteria was observed.
In three-fourths of the sites investigated in the Asgard Range
(Taylor Valley), subsurface microflora was more abundant than the 5 surface microflora, but maximum total abundance did not exceed 10 per gram of soil (Cameron and others, 1968a), The presence of boron
(7 to 16 ppm) at some locations could have presented toxicity problems, however (Cameron and others, 1968b),
Ugolini and Perdue (1968) reported that at one site in Wright
Valley, ferric iron tends to increase in quantity at the abiotic surface of rocks, whereas its quantity remains almost constant under a lichen crust, Ugolini and Grier (1969) studied Ornithogenic Soil 50 samples to determine the effect of the biological component of soils, but quantitative results are not yet in print. Preliminary results indicate that the ratio of uric acid to oxalic acid is a possible technique for providing the relative age of guano and thus, indirectly, of the site.
Protozoa, primarily ciliates, rotifers, tardigrades, and nematodes have been described from numerous lakes and ponds in southern Victoria
Land. Tardigrades and nematodes are present in Lake Vanda and the small pond south of Lake Vanda, Canopis Pond. Two arthropods are present in Wright Valley in areas where meltwater is present:
Collembola (springtails) and mites. Mites have been collected from areas covered by meltwater on the east side of Meserve Glacier
(Miss T. Tickhill, personal communication).
Primary environmental factors influencing the distribution of terrestrial plants are wind, soil composition, soil moisture, substrate characteristics, and atmospheric water-vapor content
(Scofield and Rudolph, 1969). The number and activity of arthropods and soil microorganisms are greatly restricted by lack of available water. Soil sites were chosen on the crests of moraines marginal to
Meserve Glacier to eliminate the effect of organic components in soil formation. The crests are situated above the water supply from seasonal melt, and wind abrasion, rapid evaporation, and a lack of snow cover inhibit plant growth at these locations.
(3.) Salts in Antarctic Soils
(a.) Location of Salts
The accumulation and efflorescence of salt in the cold deserts of 51 Antarctica are evidence of the extreme aridity and low precipitation
in ice-free areas. Salts are ubiquitous in exposed areas of southern
Victoria Land, Antarctica, but there is great variation in
composition and concentration (Table 9).
Salts may be dispersed throughout the dry-permafrost and active
zones of soils, or they may be concentrated in layers within 5 to 10 cm
of the surface. Salts accumulate at depth in older soils and cement
finer-grained particles to pebbles and boulders. When salts are
concentrated within the soil, completely indurated zones 4 to 10 cm
thick may be formed. Crusts of free salt and carbonate are found
beneath surface pebbles, cobbles, and boulders, but the presence of
carbonate crusts depends on a suitable source rock for CaCO^,
apparently either marble or limestone, within the underlying soil.
Calcium carbonate crusts beneath surface fragments are conspicuously
absent from all alpine lateral moraines of Meserve Glacier.
Numerous geochemical studies have been made of lakes and ponds
in southern Victoria Land Barghoom and Nichols, 1961; Angino
and others, 1964, 1965; Armitage and House, 1962; and Jones, 1969).
Ionic concentrations many times greater than that of sea water are
reported, and upon drying, brines of small saline ponds produce highly soluble chloride, sulfate, nitrate, and iodate minerals (Table 9).
(b.) Movement of Salts
The presence of salt efflorescences is a result of arid conditions, but the origin and the mechanism of ionic/molecular translocation are
still imperfectly known. Ugolini and Grier (1969) investigated ionic
transport in continuous liquid-phase water films within soils in the 52 TABLE 9. Identification and Location of Salt Efflorescences Described from Ice-free Areas of Antarctica.
Salt Reference
NaCl a, c, e, f, g, i, k, n, o
MgCl2 a# g
CaCl2 d
CaCl2 »6H20 Ji s
CaSO.*2H„0 b, d, e, f, g, i, k, 1, m, n, q, r 4 2
MgS04 g» i
MgS04»7H20 (Epsomite) d, e, m
Na2S04»10H20 (Mirabilite) d, h, 1, p
Na2S04 (Thenardite) a » f» S» m» o» P
CaCO^ a, b, f, g t if k f «nf q, r
NaN03 d, e, f
NaI03 f, m
K2S04*CaS04H20 (Syngenlte) q
Sulfur
References i a - Ball and Nichols (1960) Marble Point b - P6w£ (1960a) Miers Valley c - Kelly and Zumberge (1961) Marble Point d - Gibson (1962) Victoria Valley e - Hamilton and others (1962) Taylor Valley f - Johannesson and Gibson (1962) Victoria Valley g - Nichols (1962) Wright Valley h - Rivard and P e W (1962) Taylor Valley i - Nichols (1963) Wright Valley j - Tedrow and Ugolini (1963) Don Juan Pond k - R. Black and others (1965) Taylor Valley 1 - Black and Bowser (1968) Hobbs Glacier m - Claridge and Campbell (1968) Roberts Massif n - Black (1969) Taylor Valley o - Black and Twomey (1969) Hobbs Glacier p - Dort and Dort (1969) Miers Valley, Prince Olav Coast q - Lindholm and others (1969) Roaring Valley r - Stephens and Siegel (1969) Taylor Valley s - Wilson (1970) Don Juan Pond 36 Ross Sea region by use of radioactive sodium chloride (NaCl ). The 3 6 radioactive NaCl was placed either at the surface of the frost table or at the surface of the ice-cemented permafrost. Soil samples were collected approximately one month afterward and the redistribution of 36 Cl was determined.
Afert 40 days, the radioactive chloride tracer moved 21 cm to the surface in moist (approximately six percent water content), dark, volcanic ahumic soil at Cape Royds, Ross Island (Fig. 1). The soil had thawed during this time to a maximum of 27 cm. Thawing extended only 7 cm in the lower Wright Valley (Trilogy Glaciation surface), where the soils are lighter in color, extremely dry (one to two percent water content), and colder than those at Cape Royds, Here, the radio- 36 active Cl moved only 7 cm in 25 days, from a depth of 18 cm to a depth of 11 cm, and the frost table remained unchanged during the period of observation (mid-November to early December). 36 Radioactive Cl moved a maximum of 7 cm in a soil in the upper
Wright Valley (South Fork, west of solifluction lobe above Don Juan
Pond) which had a water content intermediate between those of soils of
Cape Royds and of the lower Wright Valley. The experiments indicated that ionic migration occurred under continuous freezing conditions and that soil formation is proceeding under extreme climatic conditions
(Ugolini and Grier, 1969).
(c.) Sources of Salts
Several sources have been proposed for the salts present in the ice-free regions of southern Victoria Land: (1) marine salts carried inland by winds or through precipitation; (2) preglacial weathering; 54 (3) present chemical weathering; (4) geothermal, either from volcanoes
or thermal springs; (5) concentration of brines and selective
precipitation from sea water, perhaps when an arm of the sea extended
into the valleys; (6) reworking of a Paleozoic salt deposit.
The majority of authors favor a wind-transport mechanism as the
source of most salts within the valleys (£•£•» Hamilton and others,
1962; Nichols, 1962; Jones, 1969; Wilson, 1970). Preglacial weathering
during warmer, Tertiary climates, with subsequent remobilization and
concentration has been suggested as the source of salts by Nichols
(1962b), Black and Berg (1963), Jones (1969), and Everett (in press).
It is difficult, however, to distinguish between relict weathering
products and salts released under the present conditions of chemical
alterations. Gibson (1962) stated that the ultimate source of salts in
Victoria Valley was chemical weathering, and Everett (in press)
suggested that the origin of salts in Wright Valley was due to both
past and present weathering.
Most authors attribute the salts to more than one source. Jones
(1969) concluded that there were multiple sources for ions in Lake
Vanda, as much of the chloride, sodium, and potassium ions may have been derived from the sea, whereas most strontium, calcium, and magnesium were probably derived from local bedrock by weathering, both relict and present.
Black and Berg (1963), considering thermal springs as the source
of salts, admitted that their presence is hypothetical. Salts in
Taylor Valley could have originated when an arm of the sea occupied
the valley bottom, but a high bedrock threshold (Bull, 1960) at the 55 east end of Wright Valley, if continuous across the valley, would have
prevented sea water from entering. No evaporite beds have been
described from the Paleozoic section in Wright Valley.
Brocas and Delwiche (1963) studied ion concentrations in snow near Roi Baudouin (70°26* S, 24°19' E) and stated that chloride ion concentrations decrease from the coast but the 1.8 Cl/Na ratio of sea water was not found in any precipitation sample. Wilson and House
(1965) analyzed snow at the South Pole (1700 m altitude, 1600 m from
the ocean in summer) and concluded the following annual ionic infalls:
Na, 10 ^ g/cm^; K, 5 x 10 ® g/cm^; Cl, 2 x 10 ^ g/cm^; NO2 + NO^ , -8 2 5 x 10 g/cm . They concluded that the sodium, potassium, and chloride came from the oceans and that the nitrogen, as N0£ and NO^ , came from auroral activity and other geophysical phenomena in the upper atmosphere. Surface snow from the edge of the air strip at the foot of the Beardmore Glacier (100 m altitude, 800 km from the ocean in summer) contained 0.13 ppm Na and 0.05 ppm K, ten times greater than at the South Pole.
Fischer and others (1969) reported concentrations of particles in
3 the air of Antarctica between 0.01 particles/cm in upper Taylor Valley
3 and on the Ross Ice Shelf, to 1.0 particles/cm at 5000 feet on Mount
Discovery. More than 50 percent of all particles ranged from nearly pure sulfuric acid to nearly pure ammonium sulfate, and some (less than 10 percent) may have consisted of sodium chloride.
Ice from Wright Lower Glacier was analyzed by Angino and others
(1964), with the following results: conductivity, 76 pmohs; HCO^ ,
12 (ppm); Cl, 14; K, 4; Na, 6; Ca, 7; Mg, 1, Wilson and Hendy (1968) 56 found consistent values for sodium and calcium in ice samples from
(1) the polar plateau above Taylor Glacier, (2) ice cores from Wright
Upper Glacier (sic), and (3) ice which had fallen down the Airdevron 6
Icefall to Wright Upper Glacier (sic). The concentration of sodium was
0*08 ppm, and the total salt content was 0.2 ppm. They calculated the
total salt production at the front of Wright Upper Glacier of 800 tons/ 2 1000 years assuming a yearly ablation rate of 10 cm over the 41 km
surface. 87 86 Jones and Faure (1967) reported the Sr/ Sr ratio in ice and
snow from the Meserve Glacier to be identical with the isotopic
composition of Sr in water of the Ross Sea, but as yet no one has
analyzed precipitation at Meserve Glacier for salt content. Ionic
concentrations of sodium and calcium in surface ice samples from the
Meserve ice-tongue were consistent with concentrations in surface neve at Meserve Glacier (Na, 0.55 ppm; Ca, 0.33 ppm) while potassium ion concentrations varied between 0.2 and 0.5 ppm (Holdsworth, 1969).
These concentrations represented salts carried by winds and precipitation and recycled salts blown from the surrounding cirque walls.
(4.) Characteristics of Soils of Ice-free Regions
Most of the ice-free areas of Antarctica are in the coastal climatic region (Weyant, 1966). The characteristics of soils of
Victoria Land, Ross Island, Inexpressible Island, Cape Hallett, Mirny and the Bunger Hills, and Enderby Land have been reviewed by Ugolini
(1970). Soils from southern Victoria Land were first analyzed by
Jensen (1916) who reported on four samples (three from Cape Royds, one from Taylor Valley) collected during Shackleton’s 1907-09 expedition. 57 He described the alkaline nature, the low organic content, and the high soluble salt content of the soils. Blakemore and Swindale (1958)
confirmed these findings through analyses of soils from Scott Base,
Ross Island, and, in addition, emphasized the very high content of
exchangeable potassium and sodium. The first attempt at grouping soils according to length of time that the parent materials had been exposed to soil-forming processes was made by McCraw (1960), in
Taylor Valley.
During the past ten years, numerous pedological investigations have been made in southern Victoria Land. The following are major references pertinent to the study of soils developed on moraines of
Meserve Glacier: Mount Erebus (Ross Island): Ugolini (1967); Taylor
Valley: McCraw (1960, 1967), Claridge (1965), Linkletter (1971);
Marble Point: Kelly and Zumberge (1961), Nichols and Ball (1964);
Wright Valley: Ugolini (1963, 1964), Ugolini and Bull (1965), Tedrow
Ugolini (1966), Ugolini and Perdue (1968), Cameron and Conrow (1969a, b), Jones (1969), Everett and Behling (1970), and Everett (in press).
All soils in southern Victoria Land are similar in that they reflect development under cold-desert conditions. Low moisture availability and low temperatures lead to very slow rates of chemical weathering, so that physical weathering predominates. High evaporation rates result in the concentration of calcium carbonate and soluble salt efflorescences on or near the surface. Significant differences in soils in this region are caused by one or more of the following conditions: increased organic activity, increased water supply, geothermal heating, or evaporation of saline ponds. Ugolini (1963) has shown that the moisture regimen of soils uninfluenced by local snow patches is dictated by the depth of the ice- cemented layer below the soil surface. Evaporation and movement of soil-moisture in the active zone results in the formation of salt efflorescences on or near the soil surface (Ugolini and Perdue, 1968).
With time, the ice-cemented surface recedes below the zero-isotherm level resulting in a zone of "dry permafrost" (Ugolini, 1970).
Ugolini and Bull (1965) attempted to relate soil formation to the glacial history in Wright Valley. They concluded that with appropriate precautions, parameters such as moisture content, depth to the ice- cemented layer, percentage of silt and clay, salt concentration, and free-iron oxide content could be used as criteria for soil development and as indices of the relative age of moraines. Calkin
(1964a) and Everett and Behling (1970) reported that surface weathering- indices and particle-size distribution within soil profiles were valid indices of the relative age. These authors, however, as well as
McCraw (1960, 1967) and Claridge (1965), stressed the difficulty in distinguishing the effects of time from local variables (lithology, microclimate, etc.) in the formation of soils.
According to Claridge (1965), the dominant process of clay formation in Antarctic soils under the present climate is the weathering of mica. Through chemical weathering, micas tend to expand and become vermiculite A (hydrated mica) or vermiculite B (non collapsing, after potassium saturation). He interprets the presence of montmorillonite in soils derived from marble, dolomite, and greywacke as being favored by aridity and high pH. Halloysite tubes 59 were revealed by electron microscopy, but their origin was not determined. These results were not in accord with those obtained by
Kelly and Zumberge (1961); an intensive study of exposed quartz-diorite rocks revealed that clays were not being formed and that the only chemical alteration was the oxidation of ferrous iron, in biotite and pyrrhotite, to ferric hydroxides,
Ugolini (1970) and Everett (in press) stress the importance in the Antarctic of considering that chemical weathering may be a relict of past climatic conditions rather than a result of present conditions.
The chemical breakdown of feldspars to form clay minerals, as reported by Ugolini (1964) and Claridge (1965) in southern Victoria Land, may have occurred during a wetter climate, while the salt accumulations developed under even more arid conditions than presently exist
(Ugolini, 1964). CHAPTER III
MESERVE GLACIER: PHYSICAL GEOGRAPHY, GLACIAL GEOLOGY, AND PEDOLOGY
A. Physical Geography
Meserve Glacier (Fig. 11) is one of several cold-based glaciers which flow northward from separate cirques in the Asgard Range into
Wright Valley. The glacier is about 8 km long with an accumulation 2 2 area of 8.1 km and an ablation area of 1.8 km . Most of the accumulation area lies between 1200 m and 1500 m elevation. There is a pronounced shoulder of the Asgard Range at about 1130 m, and the glacier extends to 400 m elevation with an average slope of 12° *
The tongue of the glacier is approximately 600 m wide before narrowing to a point, and it terminates in a vertical cliff about
20 m high. This cliff extends with diminishing height for 1200 m and 2400 m on the east and west sides, respectively, before changing into a ramp (Holdsworth, 1969). Bull and C a m e i n (1970) state that the mass balance of the Meserve Glacier is nearly in equilibrium.
A plan of the Meserve Glacier ice-tongue and a cross-section of the glacier and the moraines on the east side of the glacier are presented in Fig. 12. The topographic profile and projected cross- section of the moraines on the east side of Meserve Glacier (Fig. 13) were drawn from tape and level data collected by Everett and Behling in 1967.
60 61
Figure 11. Meserve Glacier. Lateral moraines on west (right) side are darker due to abundance of Ferrar Dolerite and volcanic rock fragments. Volcanic cones in Meserve accumulation basin are not visible from this angle. Onyx River (0), Ferrar Dolerite (F), Asgard Formation (A). B. Glacial Geology
Five of the alpine glaciers originating from cirques in the
Asgard Range in Wright Valley have similar records of past glaciations.
From east to west, these glaciers are: Goodspeed, Hart, Meserve,
Bartley, and an unnamed glacier (Fig. 5),
The unnamed glacier west of Bartley does not maintain an ice- tongue extending into the valley under present climatic conditions.
This glacier was very sensitive to fluctuations in accumulation in the past, however, and six or more distinct looped end-moraines are present on the valley wall (Fig. 5). Alpine III moraines of this glacier are several times larger than younger moraines, indicating a relatively longer stillstand during Alpine III Glaciation, At least one axial glacier from the east (Pecten Glaciation) overran portions of Alpine III moraines of this alpine glacier.
Bartley Glacier is the largest of the five glaciers; its ice- tongue reaches the valley bottom. Alpine II moraines cover the up- slope portions of Alpine III moraines on the east side, and the diff erences in surface weathering characteristics are striking. The Alpine
II moraines appear to be constructional features representing several glaciations (Behling and Calkin, 1970). A massive lateral moraine complex on the west side of the glacier extends to the valley bottom,
A ground moraine apron 3 to 4 m thick spreads in front of Bartley
Glacier at the bottom of the slope. Moderate topographic relief is provided on this apron by two intermittent looped end-moraines and stagnant-ice features. These constructional features were a result of the multi-phase Alpine II Glaciation, with the most recent phase 63 ° 371 in
468m
490m
0 100 400 m
a. Plan of the Ice-tongue. Location of b' on the Alpine II Moraine at the Meserve Glacier Hut.
b. Cross-section of the Ice-tongue and Alpine II and Alpine III Moraines. No vertical exaggeration.
Figure 12. Meserve Glacier Snout.
(After Holdsworth, 1969) MORAINE CROSS-SECTION MESERVE GLACIER W
3E o 490.7 m \ a.*.I. ICE CLIFF n r
BEDROCK V.E. 4 m
Figure 13, Topographic Profile and Projected Cross-section of Alpine II, Ila, and III Moraines on the East Side of Meserve Glacier.
O' -p- extending the farthest out.
A minimum date for the Alpine I retreat in Wright Valley may be
provided by a date of 1970 + 95 radiocarbon years B.P, (1-4984) at
Bartley Glacier (Behling and Calkin, 1970). Skin and fractured bones
of a crabeater (?) seal are incorporated in small terraces 15 to 30 cm high, 3 to 5 m from the ice-cliff.
Alpine III moraines of the Bartley Glacier were overrun at least once by westward-flowing axial ice (Pecten Glaciation) and perhaps
twice (Loop and Pecten Glaciations). Volcanic erratics are present only on the surface of Alpine III laterals on the east while volcanics
are numerous upon and within Alpine II laterals on the east. The volcanic cone dated by Armstrong and others (1968) at 3.5 m.y. is on the west side of the Bartley ice-tongue and was overrun during the
Alpine III Glaciation, Younger volcanic cones are probably present beneath the ice along the eastern portion of the glacier and account for the volcanic material found within Alpine II but not within Alpine III moraines on the east side. A similar situation exists for the Meserve
Glacier, where volcanic eruptions apparently pre- and post-date the
Alpine III Glaciation.
Hart Glacier has distinct Alpine II lateral and end moraines,
Alpine Iil laterals and especially end-moraines have been reorganized by both Pecten and Loop axial Glaciations. Hart Glacier ice-tongue extends to the foot of the slope at the present time. Very little debris was deposited on the eastern side of the glacier. Alpine I moraines are small, discontinuous, and ice-cored, and they are present only at high elevations near the present equilibrium line. 66 Goodspeed Glacier has in the past formed two ice-tongues. At about
the present equilibrium-line elevation, a small ice-tongue flowed down
a northeast-facing slope. The main ice flow was channeled northwest
and flowed obliquely down the south wall of Wright Valley. Alpine III
deposits were reorganized by later axial and alpine glaciations, and
Alpine II lateral moraines are multiple. Ice-cored Alpine I moraines
are present a few meters from the margins of the present ice-tongue.
Lateral moraines of the Alpine III Glaciation are prominent on
both the east and west sides of Meserve Glacier (Fig. 11). A looped
end-moraine is absent, although the dashed line in Fig. 9 connects
mounds which may represent reworked Alpine III deposits. A single
Alpine III lateral moraine on the east side forms a distinct ridge
which ends at a large kame-like knob at an elevation of 371 m. Alpine
III laterals on the west side are multiple and form a thin cover which
cannot be traced to the valley floor. Subsequent Alpine Glaciations
covered much of this complex and meltwater reworked surface materials.
The drift is composed of volcanics, Ferrar Dolerite, and metasediments.
At soil pit WVM-22 (Fig. 9) more than ninety percent of the parent material is volcanic. Either part of the Alpine III moraine on the west side is in fact a volcanic cone, or one or more volcanic cones
are present beneath the western half of Meserve Glacier. Wind-blown volcanic fragments are present on the surface of the Alpine III lateral moraine on the east side, but no volcanics have been recognized at
depth within the moraine.
Large volcanic erratics (greater than 10 cm long) on the surface
of the Alpine III moraine on the east side of Meserve Glacier mark the minimum extent of the Pecten Glaciation on the south wall. The erratics 67 are the principal evidence for establishing that the Pecten Glaciation
post-dates the Alpine III Glaciation. The Pecten Glaciation apparently
overran portions of Alpine III laterals without destroying their form.
This suggests that Pecten ice was cold-based. Neither an ice-core nor
an ice-cemented layer is present within two meters of the surface of
the Alpine III moraine, and neither seismic nor resistivity investiga- ■ » tions have located an ice-core within the moraine.
A subdued Alpine III ridge less than 100 m in length lies between
the major Alpine III moraine and the Alpine II complex at 470 m ele vation on the east side. It is partially covered by Alpine Ila drift.
Bedrock crops out between the Alpine III and Alpine Ila moraines on the east side and between the Alpine III and Alpine II moraine complex on
the west side. In the bedrock-based channel between the Alpine III and
Alpine Ila moraines on the east side, microdiorite dikes stand about
0.5 m above the surface of the metasediments, Meltwater, originating from the ice-margins of younger glaciations, once flowed in this channel. Glacial-fluvial sands are deposited against the proximal slope of the Alpine III moraine and sand wedges are buried by the alluvial fans.
Alpine II lateral and looped end-moraines are not continuous around the Meserve Glacier ice-tongue. The lateral moraines are mul tiple on the east side and the volume of drift decreases markedly below
450 m elevation. Discontinuous deposits on the steep bedrock face be tween 370 and 240 m elevation line up with a looped end-moraine 3 to 7 m in height on the valley floor. Till was deposited on the valley floor and some rhythmites collected in melt pools on thin, stagnant ice. The 68 rhythmites are now incorporated in the end-moraine and dip at steep
angles toward the glacier.
The Alpine II lateraL moraine is ice-cemented 90 to 114 cm below
the surface at an elevation of 470 m on the east side and an ice-core
may still be present. Volcanic rocks are present at depth within all
Alpine II moraines. A line of boulders on bedrock connects the looped 1 end-moraine with a complex of Alpine II ridges on the west side of the
glacier. Ridge crests are discontinuous and a melt channel cuts through
this complex at an elevation of 600 m. Meltwater has affected much of
the ground moraine between the proximal slope of the Alpine II moraine
and the present ice cliff. Active solifluction features and stream
flow continue to reorganize debris 100 to 150 m from the ice-tongue.
Meltwater cut two channels in bedrock in front of the present ice-front:
one at the apex of the snout, the other near the margin of the Alpine II
deposits on the east side. The time of formation of these channels is not known. There is a greater volume of meltwater on the eastern side of Meserve Glacier than on the western side because of longer exposure
to direct sunlight.
Small terraces 10 to 20 cm high continue to form under saturated
ground conditions near the snout on the east side of the glacier. Steps
1.0 to 1.5 m in height are also forming by snowbank- and spring-sapping
in the bedrock rubble to the west of the snout. Several meltwater channels breach the looped end-moraine and join Onyx River during the summer (Fig. 11). Alluvial fans, solifluction, and mudflows are not active on the distal side of Alpine II moraines, except where the moraines are breached by running water. 69 Discontinuous Alpine I moraines are present on both sides of the
ice-tongue between 500 m and 900 m altitude. These mounds are adjacent
to blue glacier-ice at their upper end near the equilibrium line and
are 5 to 10 m from the ice-cliff at lower elevations. They are ice-
cored and stand 1.0 to 1.5 m high. A boulder-rubble mantle 10 to 50 cm
thick overlies the ice-core (Fig. 14).
t Patterned ground is present on gentle slopes where meltwater is
available during part of the year and where an ice-cemented layer is
close to the surface. In addition to the previously described steps
and terraces, nonsorted polygons are forming about 950 to 1000 m above
sea level on the east side of Meserve Glacier, where an active layer
10 to 12 cm thick overlies ice-cemented debris. Wind-drifted snow
banks probably retreated from this site during the past few hundred
years. Sand- and ice-wedge polygons are present on the flanks of the
volcanic cones in the accumulation basin and at the edges of snowfields
in the accumulation zone. Relict sand-wedges and mudflows can be dis
cerned on the surface of Alpine II moraines. Non-sorted polygons are
absent from Alpine III moraines, but patterned ground is commonly
found on reorganized Alpine III debris near meltwater channels asso
ciated with the Alpine II Glaciation. Sorted stone nets are present
in the area affected by meltwater east of the snout.
Surface weathering characteristics of Alpine III, Ila, II, and I moraines are distinct. Observations on cavernous weathering, boulder
erosion, and ventifaction have been used by many authors as evidence
for relative age of materials in southern Victoria Land (£.£_•, Pewe^
1960; Calkin and Cailleux, 1962; Cailleux and Calkin, 1963; Everett and 70
Figure 14. Crest of Alpine I moraine and WVMC 6 Profile. Looking upslope near top of ice-fall of Meserve ice-tongue. Note lack of cavernously weathered boulders and ice-core at a depth of 6 to 8 cm. Only a portion of the ice-core is exposed; material in foreground is downslope crest of moraine. 71 Behling, 1970). Few upstanding boulders remain on the surface of the
Alpine III moraine below the minimum elevation of the Pecten Glaciation.
Above this elevation, in the vicinity of WV-1 (Fig. 15), the few
boulders remaining above the surface are cavernously-weathered.
Occasional ventifacts can be found on the desert pavement, but slopes
of 10 to 20° prevent formation of ventifact fields. Polished surfaces
are common on fine-grained dike rocks.
The surface of the Alpine III moraine is dark because of the
abundance of microdiorite- and lamprophyre-dike pebbles, cobbles, and
boulders. A weathering index based on a ratio of the percent of
resistant rocks at the surface (r^) to the percent of resistant rocks
at a depth of 50 cm 3,43 for the Alpine III moraine (Table 10).
Other physical weathering indices determined within a circular area 20 m
in diameter are 4.5 boulders more than 10 cm above the surface; 37.8
boulders planed to surface; 7.5 dike rocks more than 20 cm long.
Calkin (personal communication) and Everett (in press) consider
the Alpine Ila moraine to be a phase of the Alpine II Glaciation. The
surface weatheting-indices, however, are intermediate between those of
Alpine Glaciations III and II (Appendix A). The Alpine Ila surface is much lighter in color than the Alpine III surface, and numerous up
standing boulders are present (Fig. 16). Nearly all upstanding boulders are cavernously-weathered. Weathering indices are as follows:
surface to depth resistant rock index, X-Jx2. ~ 41*5 boulders more
than 10 cm above surface; 20,0 boulders planed to surface; 21.5 dike rocks more than 20 cm long (Appendix A).
Some boulders on the Alpine II moraine are cavernously weathered. 72
Figure 15. Surface of Alpine III lateral moraine; view upslope from WV 1 soil pit. Note cavernous ly- weathered and planed boulders. Compare this surface with that downslope (Fig. 38) on the same crest, to observe effect of Loop and Pecten Glaciations in leveling the surface. The ice-axe for scale is 1 m long. Alpine II moraine (II), Meserve Glacier (M), Asgard Formation (A) with Lamprophyre and Porphyry Dikes. Figure 16. Crests of Alpine II, Ila, and III moraines, looking downslope from an elevation of 900 m. Meserve Glacier to the left. Note Alpine III looped end-moraine in valley bottom (E) which has been altered by Axial Glaciations. TABLE 10. Physical Weathering Criteria, based on condition of larger clasts
ALPINE I ALPINE II ALPINE III
Resistant Rocks 10 0 7 ?0 ft 7 lj a 7 At Surface X 1 10,0 7o 20,8 7o 4 2 *6 %
Weathering Index 3 N*D» ^ 2,88
Number of Boulders: Circular Area, Radius 10 m
Boulders >10 cm N.D. 90.0 4.0 Above Surface
Boulders Planed To Surface N.D. 22.5 37.6
Dike Rocks, Max. N.D. 21.0 4.3 Dimension >20 cm
r^: Percent resistant rocks at a depth of 50 cm. k Not Determined. fmJ The bouldery surface distinguishes the multiple crests of this moraine from the crest of the Alpine III moraine. A surface to depth resistant rock ratio of 1.14 is close to unity which would define a moraine for which there was no increase of resistant rocks on the surface.
Weathering parameters within the circular areas are as follows: 90.0 boulders more than 10 cm above surface; 22.5 boulders planed to surface
* 21.0 dike rocks more than 20 cm long (Appendix A).
Alpine I lateral moraines are presently forming and the weathering parameters could not be applied. Boulders on the surface are un weathered, but they may be iron-stained; cavernous weathering is absent
Finer material winnows down between the boulders to insulate the ice- core. Boulders are commonly frozen to the ice-core and the debris is poorly sorted by winnowing (Fig. 14).
C. Soils of the Meserve Glacier Area
Soils of the Meserve Glacier area have been studied in detail by
Everett and Behling (1968, 1970) and Everett (in press), while Holds- worth (1969) and Jones (1969) have described the salts associated with
Meserve Glacier and the surrounding glacial drift. The soils are quite simple morphologically and are differentiated on color, texture, amount of free salts, degree of salt induration, and the amount of granules and cobbles up to a size of 35 cm (coarse skeleton).
Soil color (Munsell color values on dry, loose soil) is generally pale brown (10YR6/3) except for the upper few centimeters of older profiles (Alpine II, Ila, and III) which may be yellowish brown
(10YR5/4). Below 50 cm it is common that both chroma and hue increase to very pale brown (10YR7/3 or 7/4) (Everett, in press). Profiles of 76 the Alpine I moraines seldom show even weak color differentiation.
Textures of all soil horizons described from the Meserve Glacier area are characterized by coarse or medium sand. Everett (in press) reported an increase in total clay-size particles within the upper 20 cm of profiles from moraines of Alpine III and Ila glaciations. This increase is frequently associated with an increase in total silt and T is always associated with a salt-indurated horizon. Both the intensity and the depth of the clay-bulge peak appears to be greater in the older soils.
The most significant physical or chemical characteristic of the soils around Meserve Glacier is the salt-indurated layer or horizon.
Salt induration in younger soils is present as delicate, thin, weakly bound zones, small patches of aggregated fines and skeletal material, or both. In older soils, the salt indurated layer is massive and thick
(up to 15 cm) and can withstand repeated blows with a trenching shovel.
Salt concentrations may vary within a single moraine but in general the depth of the salt horizon within the profile and the degree of develop ment of the induration are greater in older deposits. Thin sections of the salt-indurated horizon from the Alpine III moraine indicate that individual sand grains are in a salt matrix. Thin sections, prepared by impregnating the samples with Castolite, revealed that grains of pyroxenes and feldspars within salt horizons in the ground moraine distal to the Alpine III crest, the Alpine III crest proper, and
"Pecten Moraine" deposits, are corroded on the edges and displayed a lustrous, pebbly birefringence (Everett, in press).
The coarse skeleton (up to 35 cm in diameter) is nearly completely 77 disintegrated to a depth of 30 cm in the Alpine III moraines, hut it
is relatively fresh in the Alpine II moraine. Boulder skeleton is very high in all moraines but compaction is greatest in the older moraine,
•where boulders are firmly keyed and interstices nearly filled with
sands and other fines. Excavations in the Alpine III moraine were
opened with difficulty but walls did not cave. It was nearly
impossible, however, to keep the walls of the pits in the Alpine III moraine from caving in, although digging was relatively easy. Everett
(in press) attributed the compaction of the morainal debris to settling,
as the ice-core melted.
Age relationships cannot be based solely on depth to ice-cemented
permafrost in moraines of Meserve Glacier (Everett and Behling, 1970),
In late November, 1967, the depth of ice-cemented permafrost on the east side of the glacier was 6 to 8 cm on the Alpine I moraine, 98 cm on the Alpine II moraine, 110 to 150 cm on the Alpine Ila moraine, and greater than 190 cm or absent on the Alpine III moraine. These depths were determined at about 500 m elevation for the Alpine II, Ila, and
III moraines and at about 950 m elevation for the Alpine I moraine.
The contact between the loose soil and the ice-cemented layer is abrupt and uneven. Pebbles are frozen to the ice-cemented layer and protrude above its surface. The surface appears to have either melted and refrozen or have resulted from sublimation. Below a depth of 1 m, only sublimation can lower the surface of the ice-cemented layer under present climatic conditions.
Everett (in press) described several chemical characteristics of the soils which correlate with an increase in clay content and the salt- indurated layer. Sulfate-ion concentration, exchangeable sodium and 78 electrical conductivity profiles are similar to those of silt-clay and si t distribution. Profile development of these same chemical parameters increases in intensity with age. A decrease in pH with depth is diag nostic only of the salt-indurated layer due to soluble sulfates, and pH profiles show no particular trends among moraines of different ages.
Everett (in press) located montmorilIonite in horizons coinciding with an increase in silt and clay, and in the salt-indurated layer of three profiles on the Alpine III moraine (east side). He does not consider clay-mineral identification to be a conclusive index of chemical weathering, however. Everett also suggests that most, if not all, of the exchangeable sodium present in soil profiles on Meserve
Glacier moraines was added to the profile rather than resulting from chemical weathering. The relatively strong morphological and chemical development of many profiles suggests that the bulk of the salts present in the soils are products of past environments. There was more chemical weathering in these relict environments, but they were also desertic as salts were not leached from the soils. There was sufficient moisture to allow at least seasonal migration of salt to specific horizons. Everett suggests that pedologic development took place under slightly warmer and more moist periods which were separated by colder, drier periods, similar to present conditions. CHAPTER IV
PHYSICAL PARAMETERS OF PEDOLOGICAL DEVELOPMENT
A. Soil Temperature
Soil temperatures from several Antarctic climatological regions have been reported (e.£., Benes, 1960; Black and Berg, 1963; Ugolini,
1963; Ugolini and Bull, 1965; Chambers, 1966; and Solopov, 1967).
Soil temperatures were recorded at sites in Wright Valley by Ugolini
and Bull (1965), and monthly averages of temperatures at depths of
8 inches and 10 feet are available from Vanda Station (Table 1).
In 1968-69 and 1969-70, thermistors (Yellow Springs Instrument
Company) were buried 50 cm in the Alpine III moraine and to the
ice-cemented layer in the Alpine II moraine, and temperatures were recorded by a YSI telethermometer Model 42 SL. Temperatures in the
Alpine II moraine were recorded discontinuously during 1969-1970 while
temperatures in the Alpine III moraine were monitored discontinuously during 1968-69 and 1969-70 (Figs. 17 and 18, and Appendix D), A minimum of one week was allowed for soil and probe to reach
temperature equilibrium with the surroundings before readings were monitored.
Temperatures at the ice-cemented layer (91 cm) in the Alpine II moraine increased 8.5°C between 18 November 1969 and 19 January 1970.
The largest temperature difference measured in this 91 cm was 26.3°C on 19 January 1970, at 1415 McMurdo time, when the surface temperature
79 Surface
2 0 "----!---K 1700 Depth 0------o 2 2 0 0 "------* 0 8 0 0 8 January, 1969 cm 30 +— +2200
4 0
50
.4 -2
Degrees Centigrade
Figure 17. Selected Temperature Profiles: Alpine II: Moraine, 1969 ai TEMPERATURE PROFILES
011170 - 011570
SURFACE
10 cm 20 cm •C 30cm
AIR
-10 1000 22001000 2200 1000 2200 1000 1000 JAN. 13 HOURS ALPINE HI
c
3 0 cm
30cm
AIR
-10 1000 2200 1000 2200 1000 2200 1000 2200 1000 JAN. 13 HOURS ALPINE H Figure 18. Selected Temperature Profiles: Alpine II Moraine, 1970. 82 was +20.1°C (Appendix D). Temperature differences of 20°C or more
between the surface and the ice-cemented layer during mid-November
are common.
The microclimate at the two sites monitored on the crests of
Alpine III and II moraines east of Meserve Glacier differ, due to
proximity of the Alpine II moraine to the ice-cliff. Strong easterlies
passing over Alpine III moraine continue over Meserve Glacier (Fig, 13) with a lessening of wind velocity at the Alpine II moraine. Numerous
upstanding boulders on the Alpine II surface disrupt cooling winds,
so that surface temperatures are higher there than on the Alpine III moraine, despite the dark-pebble armor covering the Alpine III moraine (Fig. 16). Westerlies over Meserve Glacier also affect the
Alpine III moraine to a greater extent than the Alpine II moraine.
The ice-tongue casts evening shadows upon Alpine II moraine
about two hours before the sun passes behind the Asgard Range. In
the morning, the sun shines on Alpine III moraine only slightly
earlier than on Alpine II moraine. Although net radiation flux is
greater on the Alpine III surface under cloudless conditions, the
Alpine II soil is warmer to depths of 20 cm because winds are deflected
from the surface. Surface temperatures of +14°C to +16°C are not
uncommon and are maintained for eight to ten hours per day under
cloudless conditions. The amplitude of diurnal temperature variations
decreases with depth, being only 1 to 2°C at 30 cm and being discernible
at 50 cm in the Alpine III moraine. Diurnal temperature variations
in Alpine II soil are nearly dampened out at a depth of 30 cm due to
the high heat capacity of the ice-cemented layer.
Ice and adsorbed water can be in equilibrium in a soil at 83 temperatures several degrees below freezing, and as moisture content
is reduced, the freezing point is depressed further below 0°C
(Schofield, 1935). The deepest penetration of the zero-degree iso
therm therefore does not precisely define the depth of the active
layer. Black and Berg (1963) have proposed that as the active layer
warms and cools, air is pumped in and out of the soil and moisture is
transferred by that circulation and by the impetus of a marked vapor
pressure gradient. The upper 30 or 40 cm of soils studied in the
Meserve Glacier moraines would be subjected to such air exchange, and
small quantities of moisture are probably added to the soils by this
mechanism.
Owing to the transfer of moisture from the ice-cemented layer to
the surface (Fig. 19) the depth to the ice-cemented layer increases with time. This mechanism provides moisture to the profile which then
serves to promote ionic translocation, as shown by Ugolini and Perdue
(1969). It is not known at what rate water and ions are translocated
in a profile where there is no apparent ice-cemented layer. Certainly
the unfrozen film is not continuous through the soil matrix, and it is
doubtful whether a continuous film can exist except where ice-cemented material is within 30 to 50 cm of the surface. Where a potential water
source is near the surface, however, temperature and vapor pressure
gradients are steep enough to maintain a moisture content of several percent throughout the profile.
Representative salt concentrations for Alpine-moraine soil
profiles indicate lowering of freezing point on the order of 3 to 5 degrees Centigrade depending upon the salts present. Moisture pumped Surface
/Y DIURNAL AIR PUMP ACTIVE ZONE
Max. Depth N Zero Degree 3 0 ' 40 Isotherm
DRY PERMAFROST SUBLIMATION / ' l
ICE * CEMENTED
Figure 19. Diagrammatic Cross-section of Theoretical Soil Profile. 85 into the soils, if condensed, will become unfrozen salty soil water at a temperature of about -3°C. Thus, ice crystals formed during the winter below depths of 30 or 40 cm probably do not melt under summer water vapor pressure gradients, heat influx, and temperatures.
B. Soil Moisture
The in situ soil moisture content was determined gravimetrically for samples from the Alpine II and Alpine III soil profiles (Table 11).
Soil moisture content exclusive of ice-cemented samples averages about one percent of the oven-dry soil weight. Variations are found in the upper ten centimeters of both profiles, where drying at the surface reduces water content, and near the contact with the ice-cemented layer where water content increases substantially (Table 11). The slight increase in moisture in the region of the salt horizon of the Alpine
III profile suggests the presence of deliquescent salts.
The Alpine II soil profile has a lower average soiL-moisture content than the Alpine III profile because it is subjected to greater heat energy influx and because it has a lower salt content. Heating of the upper 10 cm during exposure to direct sunlight causes evaporation and moisture migration towards the surface. Once direct sunlight no longer warms the surface, the temperature of the surface soil quickly equilibrates with the air temperature, and within two hours (Fig. 18) the temperature gradient reverses through the upper 10 cm. Cold, moist air is then pumped into the soil from the atmosphere. By early morning the highest temperature in the profile is often at a depth of about
30 cm. During the summer, the upper 10 to 30 cm of soil is subjected to diurnal changes of both temperature and direction of moisture 86
TABLE 11. Soil Moisture Content.
ALPINE II ALPINE III
Depth Moisture Content Depth Moisture Content cm Percent by Weight cm Percent by Weight
0-5 0.54 0-5 0.89
0-10 0.68 0-10 0.95
10-20 0.88 10-20 1.14
20-30 0.98 20-30 1.12
30-40 0.95 30-40 1.29
40-50 0.92 40-50 1.08
50-60 0.92 50-60 0.98
60-70 0.92 60-70 0.91
70-80 1.06 70-80 1.02
80-(88-90) 1.20 80-90 1.02
Ice-cemented 44.99 90-100 1.12
100-110 U l l
FROZEN BASAL TILL (Meserve Glacier Core): 6.03%. transport. Snowfalls, though infrequent, can be heavy enough to
provide meltwater to the soil before sublimation occurs, so that
the upper 5 to 10 cm is wetted but never saturated,
I consider the water content in the ice-cemented layer in the
Alpine XI moraine to be post-depositional, probably as a result of
ground water accumulation from meltwater flowing between the Alpine
II and Ila moraines or between the margin of the ice and the Alpine
II moraine complex. The ice-cemented mineral soil is oxidized and
iron-stained, and there is no distinct weathering change across the
ice-cemented boundary; the weathering profile must have been developing
prior to the introduction of the water. There is no preferred
particle-size distribution within the profile, indicating that the water probably moved laterally rather than percolating down through
the soil profile.
Strong vapor pressure and temperature gradients between the ice- cemented layer and the surface result in sublimation from the surface of the ice-cemented layer and vapor movement vertically in the profile.
This causes the 20 cm of soil immediately above the ice-cemented
layer to have a higher moisture content than.the rest of the profile.
The movement of soil moisture within the profile results in the
translocation of mobile ions. The accumulation of salts between 10 cm
and 40 cm in the Alpine III profile has occurred as a result of the
pumping of moist air into the soil and the percolation of meltwater
from occasional snowfalls. The horizon of maximum salt accumulation coincides with the maximum depth of diurnal temperature-gradient reversals; it remains the warmest in the evening and early morning hours when cold, moist air is being pumped into the soil from the atmosphere. Thus, salts added to the soil surface through precipita
tion are translocated to that portion of the profile which does not undergo marked diurnal temperature changes but remains warmer than the
incoming moisture-laden air.
Water can also be transported as a result of electro-osmosis in the frozen soils when there is an excess of cations over anions near soil particles (Hoekstra and Chamberlain, 1964). The horizon of increased salt concentration in Alpine III soils could effect an electrical potential within the profile, but there is no substantial water-source at depth in the Alpine III moraine. The accumulated salt horizon in Alpine II soils is much less pronounced, and although there is a substantial water source at depth, the amount of water transported by electro-osmosis must be very small.
Although soil moisture is very low, the water adsorbed by soil particles can promote slow physical and chemical reactions. Adsorbed water remains unfrozen at temperatures below zero and the expansion of such water on the surface of fine-grained particles in response to ordering or freezing aids in disintegration. Adsorbed water must certainly assist in the translocation of ions in the absence of a continuous water film.
Cameron and Conrow (1969a) measured relative humidity in soils at four sites in the ice-free valleys of southern Victoria Land, The sites were shallow, with an underlying ice-cemented permafrost layer, and they concluded that under these conditions soil moisture is present in the vapor phase. Sites were monitored during December and January, 89 and during this time their measurements indicated no obvious movement
of soil moisture in the vapor phase through the profile from the perma
frost layer to the surface. Determinations of relative humidity in a
soil in Victoria Valley indicated that despite low relative humidities
in the atmosphere (20 to 407.), there is a general increase in soil
relative-humidity with proximity to permafrost: 407. at 5 cm depth,
607, at 15 cm depth, and 907, at 30 cm depth. I suspect that in the
deeper Alpine II sites, soil relative-humidity increases only occur within 10 to 15 cm of the ice-cemented boundary due to lower temperature
gradients.
C. Soil Air
Soil-air composition in the vicinity of Meserve Glacier was not
determined. Gas compositions of Antarctic soils has been determined
in the ice-free valleys of southern Victoria Land by Cameron and Conrow
(1969b) from soils on an island in Lake Bonney, Taylor Valley, and from
a McKelvey Valley soil site. The gas samples from soils in Taylor and
McKelvey valleys suggest that the CC>2 concentration in soils is similar
to or lower than the CC^ concentration in air circulating over them,
provided there is low microbial activity. Low CO^ concentrations
within soils in southern Victoria Land probably do not accomplish clay-
mineral weathering as suggested by Wayman (1963) at sites in more
temperate climates with a marked level of organic activity.
D. Weathering of Boulders on Moraine Surfaces
Surface weathering parameters on moraine crests on both sides of
Meserve Glacier are presented in Appendix A and summarized in Table 10.
The distinct weathering surfaces of Alpine Glaciation moraines were 90
TABLE 12. Average Gas Analyses of Air: Taylor Valley and McMurdo Station,
Sample Description Volume Percent Composition
0 2 C02 N 2 Ar H20
Taylor Valley:
Air, 1 meter; 21.4 0.05 77.5 1.01 0.11 Wind NE; Dec. 7, 1967.
Air, 1 meter; 20.0 0.07 78.7 1.00 0.02 Wind SW; Dec. 8, 1967.
Air, Surface; 20.5 0.07 78.5 1.01 0.02 Wind NE; Dec, 7, 1967.
Soil, 15 cm.; 20.8 0.03 78.2 1.01 ---- Wind NE; Dec. 7, 1967.
Soil, 30 cm.; 21.2 0.03 77.9 1.02 ---- Wind NE; Dec. 7, 1967.
Soil, 60 cm.; 21.5 0.04 77.5 1.02 Wind NE; Dec. 7, 1967.
McMurdo Station:
Air, 1 meter; 20.7 0.46 77.7 0.95 0.12 Wind S; Jan. 31, 1968. 91 compared statistically by counting the number of boulders which were:
(1) more than 10 cm high, (2) weathered to the surface, (3) dike rocks more than 20 cm long. Areas 20 m in diameter were compared from all moraine surfaces. The principal factor governing the rate at which boulders are weathered is grain-size rather than lithology. Coarse grained Ferrar Dolerite disintegrates more rapidly than fine-grained
Ferrar Dolerite or microdiorite from contact zones; Asgard meta sediments, particularly marbles, and granodiorite are especially susceptible to granular disintegration.
Cavernous weathering, or taffoni, occurs when surface boulders are subjected to intergranular salt-growth, diurnal heating, and wind abrasion (Fig. 20). Boulders which are most susceptible to the variety of erosional processes are eventually planed to the surface and become part of the desert-pavement armor against further erosion. The number of boulders of all lithologies which remain standing 10 cm or more above the surface plus the number of boulders which have been eroded suggests
that the Alpine II moraine initially had more boulders at the surface
than did the Alpine III moraine. The quantity of boulders at depth within the respective moraines could not be determined.
Dark microdiorite boulders are fractured by thermal expansion and supply additional pebbles to the surface (Fig. 21). This breakdown aids in the formation of a dark-colored, resistant, desert-pavement by
increasing the percentage of these resistant rocks (r^) on the surface of older moraines (Table 10; Fig, 16).
The mineral grain-sizes within the boulders undergoing dis
integration determine the particle-sizes which accumulate on the 92
Figure 20. Cavernously Weathered Metasediment Boulder, Alpine III Moraine, East Side, Meserve Glacier. Note rounded but competent dolerite boulder in upper left, which is protected by desert varnish. Figure 21. Surface of Alpine III Moraine at Site of WV 1 Profile. Note abundance of dolerite pebbles and relative abundance of metasediment pebbles. Dolerite pebbles have been overturned to show salt- and silt-encrustations on undersides. moraine surface. Medium and coarse sand- and gravel-sized particles accumulate as coarse-grained boulders weather, while pebbles and cobbles are formed as fine-grained boulders disintegrate,
E. Pebble Lithologies: Labile versus Resistant
Because the surface of Alpine III moraines is distinctly darker than those of younger moraines (Fig. 16), surface pebble counts and pebble counts at a depth of 50 cm at the same site were compared to obtain a weathering index. A depth of 50 cm was chosen because it is below the level of boulder disintegration in the oldest soils of the sequence. At least one hundred pebbles with a maximum dimension of
5 to 10 cm were collected for each determination, and rocks were catagorized according to their susceptibility to weathering. Fine grained dolerite and metasediment, quartz, quartzite, and microdiorite are resistant rocks; coarse-grained dolerite and metasediment, grano- diorite, and marble are labile. A weathering index based on the ratio of the percent resistant rocks at the surface (*^) to the percent resistant rocks at depth (r^) was calculated (Table 10). This weather ing index for the Alpine III moraine on the east side of Meserve
Glacier was 2.88; for Alpine II, 1.13. It was not determined for the
Alpine I moraine, but the value for an unweathered moraine should theoretically be 1.00.
F. Particle-Size Distribution
Size limits of soil separates below 2.0 mm diameter (sand) were determined according to the scheme accepted by the Soil Survey Staff
(1951)(Appendix C). Particle-size distribution within representative soil profiles in Alpine I, II, and III moraines shows that the oldest soil in the chronological sequence has undergone particle-size y-) comminution iui situ causing a slight increase in percent total silt at the expense of the sand fraction (Table 13; Fig. 22; Appendix C).
Physical comminution of boulders first causes an increase in sand and gravel in the upper 50 cm, as is shown by the comparison of sand/silt ratios in the Alpine II profile. Once the boulders have comminuted to coarse-grained particles, continued breakdown decreases the sand/silt ratio in the upper 50 cm of the profile.
There is no evidence of marked particle-size concentration at any particular depth within the profile as a result of particle movement, but there is a very slight increase in the fine-clay fraction in the region of the salt horizon in the Alpine III profile (Fig. 23). Everett
(in press) has shown a slight increase in total clay in the salt horizon in the Alpine III moraine and he argues that the salt translocation and possibly the additional clay were formed when the climate was not as dry as it is today. The marked increase in clay-size particles in the upper 20 cm of the Alpine III profile and in the upper 10 cm of the
Alpine II profile is due to chemical weathering. There is also a definite increase in silt in the upper 5 cm of the Alpine III moraine and possibly in the upper 2.5 cm of the younger Alpine II moraine. TABLE L3a. Particle-size Analysis and Sand/Silt Ratios, Based on Less than 2 mm Fraction. ALPINE I ALPINE II ALPINE III Weight Percent Weight Percent Weight Percent )epth cm Sand Silt Clay Sand/Silt Depth cm Sand Silt Clay Sand/Silt Depth cm Sand Silt Clay Sand/Silt
0-6(8) 74.9 19.5 5.6 3.8 0-2h 79.8 13.4 6.8 --- 0-2% 73.3 21.0 5.7 —
2^-5 86.7 8.9 4.4 --- 2^-5 73.2 20.5 6.3
5-10 81.9 13.4 4.8 7.0 a 5-10 79.5 15.5 5.0 4.4 a
10-20 82.6 15.3 2.2 5.4 10-20 75.2 20.3 4.4 3.7
20-30 79.8 15.9 4.3 5.0 20-30 80.1 16.5 3.4 4.8
30-40 79.8 16.2 4.1 4.9 30-40 81.4 15.3 3.3 5.3
40-50 80.9 15.3 3.9 5.3 40-50 80.4 15.7 3.9 5 04
50-60 81.2 14.7 4.1 5.5 50-60 76.0 19.1 4.9 4.0
60-70 78.1 18.4 3.5 4.2 60-70 83.3 13.2 3.6 6.3
70-80 76.3 19.0 4.7 4.0 70-80 85.3 11.3 3.4 7.6
80— Ice- cemented 78.9 16.1 5.0 4.8 80-90 75.8 20.8 4.5 3.6
90-100 ——*------79.3 16.5 A.2 4.8
Average 80.1 15.9 3.9 5.1 79.2 16.7 4.1 5.0
0-50 cm 5.5 0-50 cm 4.7 interval. 50 cm + 4.7 50 cm + 5.3 TABLE 13b, Partlcle-Size Distribution of Coarse Fraction Greater than 2 mm.
ALPINE I ALPINE II ALPINE III Weight Percent Weight Percent Weight Percent Depth cm > 4 mm 4-2 mm Depth cm >4 mm 4-2 mm Depth cm > 4 mm 4-2 mm
0-6(8) 47,46 13.57 0-2% 29.23 11.31 0-2% 41.22 8.09
2%-5 17.00 9.42 2%-5 41.13 7.83
5-10 24.90 7.93 5-10 26.18 8.69
10-20 20.08 9.07 10-20 36.50 7.32
20-30 26.39 8.88 20-30 25.37 7.46
30-40 29.56 7.77 30-40 24.30 10.50
40-50 28.94 8.70 40-50 23.88 8.32
50-60 29.68 9.68 50-60 31.32 7.92
60-70 28.92 8.05 60-70 34.62 8.64
70-80 34.66 7.54 70-80 20.66 10.84
Ice-cemented 38.72 7.89 80-90 31.54 8.74
90-100 27.32 9.08
Average over 10 cm Intervals 29.00 8.52 28.92 8.71 98
A ftlpint I X Alp!** II Alpine III
20
Sapd slit 3 0 Sand Silt
4 0
Depth tn
eo
7 0
BO
00
BO 80 100 Percent
Figure 22. Particle-size Analysis. 99 o r
*
to i I ! 20 i ! I i i r f 30 i / i/ 4 0 L if 2 - 0.2 p Depth I - 0.2 p CM ¥
BO i ft f* 60 a ii
ft 7 0 w
* 80 i \ I
90
100 0 .0 1.0 2.0 8.0 4.0 S.O e.o 7.0 Perciat
Figure 23* Clay-aize Particle Distribution with Depth# CHAPTER V
CHEMICAL PARAMETERS OF PEDOLOGICAL DEVELOPMENT
A. Eh, pH, Abrasion pH, and Electrical Conductivity
(1.) Oxidation-Reduction Potential
The chemical factors most important in this environment are the
oxidation-reduction potential (Eh), the acidity-alkalinity (pH), and
the salinity. Measurement of the in situ oxidizing capacity (Eh) of
the soils in moraines marginal to the Meserve Glacier was not possible because of low soil-moisture content; thus a laboratory procedure was devised.
The measure of oxidizing capacity was determined from a 1:1 soil: water slurry stirred for two minutes; 10 grams of untreated soil, particles less than 4 mm in diameter, was stirred in 10 ml of double distilled water. One minute was allowed for the platinum and reference electrodes to stabilize, and the oxidation-reduction potential of the slurry was compared to a standard solution of 10 ^ M CaC^ (+48.6 mv).
Results of this procedure are presented in Table 15.
The highest oxidation potential recorded was from Alpine I soil due to the proximity of moisture, the ice-core at a depth of 6 to 8 cm.
Relative increases in oxidation potentials at depths of 10 to 50 cm in the Alpine III moraine and 10 to 30 cm in the Alpine II moraine reflect the higher soluble-salt content of these portions of the
100 101 profiles (Table 14), The slight rise in Eh with proximity to the ice- cemented layer in the Alpine II moraine could be caused by increased moisture content above the ice-cemented layer,
(2,) Acidity-Alkalinity
Determination of the hydrogen-ion activity of the soils was made electrometrically using an Orion 404 portable specific-ion meter. A
1:10 soil:water slurry was prepared in the laboratory using untreated particles which passed a 2 mm sieve, and pH was determined after 4 minutes of stirring. Soil pH as a function of depth is shown in Fig.
24. The pronounced decrease in pH between 10 cm and 40 cm in the
Alpine III profile is due to the increased concentration of neutral salts, £.£., NaCl and CaSO^»2H20. Despite the influence of the salts, it is apparent that there is at least one-half pH unit difference with in the Alpine III and Alpine II profiles.
(3.) Abrasion pH
The changes in soil pH brought about by chemical weathering were examined by determining abrasion pH of rock fragments by the method of
Grant (1960). Rock fragments 2 to 5 mm in diameter which contained abundant feldspar (granodiorite, light-colored metasediment) were picked from a washed sample; 3.0 g were added to 60 ml double-distilled water, ground for minutes, and the abrasion pH of the slurry was determined after two minutes of stirring. Particle size-range was dictated by ability to identify fragment lithology while maintaining maximum surface-area. The results of this procedure are presented in
Fig. 25. The washing procedure prior to determination of abrasion pH removed water-soluble salts as well as any authigenic kaolinite from 102
TABLE 14. Oxidation-Reductlon Potential in a 1:1 soiliwater slurry.
Standard: 10-1M CaCl2 (+48.6 mv)
ALPINE IALPINE II ALPINE III
Depth cm mv Depth cm mv Depth cm mv
0-6(8) +58.0 0-2% +27.0 0-2% +33.5
2%-5 +32.5 2%-5 +30.0
5-10 +31.5 5-10 +36.5
10-20 +47.0 10-20 +50.0
20-30 +37.5 20-30 +56.5
30-40 +23.5 30-40 +56.0
40-50 +21.5 40-50 +54.0
50-60 +18.5 50-60 +46.0
60-70 +24.5 60-70 444.0
70-80 +27.0 70-80 +38.0
Ice-cemented +22.0 80-90 +46.0
90-100 +39 „ 5 103
£0
30
40
Dtflfc CM
00
eo
TO
eo
eo
100 7.0 8 . 0 8.0
Figure 24* Soil pH 104 the rock fragments.
Abrasion pH determinations measure the availability of cations upon grinding: as abrasion pH declines, so does the amount of cations
(Na, K, Ca, Mg) in solution (Grant, 1969). Jenny (1950) proposed that
_L H may replace cations (M ) at the mineral surface causing the pH of
the liquid phase to rise. Stevens and Carron (1948) examined a variety of minerals and found that alkalies and alkaline earths yield abrasion pH values greater than 7.0; apparently the processes
of hydration, hydrolysis, and hydrogen replacement of cations continue
until a state of equilibrium is reached:
M+(mineral)" + H+0H~ H+(mineral) + M+0H .
Grant (1969) considers the abrasion pH as an index of weathering
comparable to the "weathering potential index" developed by Reiche
(1943, 1950) and utilized by Ruxton (1968a).
Abrasion pH values (Fig. 25) derived from Alpine-moraine soils
indicate a greater loss of cations from alkalies and alkaline earths
in the Alpine XXI profile than in the Alpine II profile. The Alpine I
soil is within the active zone above an ice-core and has been subjected
to anomalously moist conditions, so abrasion pH in Alpine I is similar
to that in Alpine III despite the great age difference. The rock
fragments obtained from a drill core through Meserve Glacier is used to
represent "fresh" parent material. Abrasion pH of the parent rock,
however, is influenced by an increased abundance of mafic accessory
minerals; a pH of about 9.0 is assumed for one unweathered sample of
the Asgard Formation. 105
i o
□ Meteree Core A Alpine I 20 X Alpine II O Alpine 111
BO
40
Depth CB
60
60
70
eo
00
10 0 7. 0 6.0 0.0
Figure 25. Abrasion pH. 106 (A.) Electrical Conductivity
Electrical conductivity of a 1:1 soiliwater mixture gives an indication of the total concentration of ionized constituents. Ten grams of untreated soil and 10 ml double-distilled water were thoroughly mixed with a magnetic stirrer and allowed to stand for
24 hours. Electrical conductivity was then measured on a Wheatstone bridge (Table 15). A high degree of positive correlation between the electrical conductivity and the total concentration of cations or anions allows the following relation:
Total cation concentration (me/liter)
= 10 x Electrical Conductivity (m mho/cm)
(Black, C. A., and others, 1965).
The total concentration of cations determined by this method has been compared with total salt content by acid digestion (Fig. 26).
B. Soluble Salt and Specific Ion Determinations
(1.) Soluble Salt
Total salt content of Alpine II and Alpine III soils was determined gravimetrically after treatment with acetic acid buffered with sodium acetate according to the method of Jackson (1958). Insufficient
Alpine I soil was available to obtain reproduceable results by this method. Soil:salt ratio as a function of depth is presented in
Fig. 26.
(2.) Specific Ion Determinations
Specific ion determinations suitable for fieldwork in Antarctica were made of selected soil samples. Relative Na and Cl concentrations were determined using specific ion probes and a 107
TABLE 15. Electrical Conductivity of a 1:1 soiljwater Extract.
ALPINE I ALPINE II ALPINE III
Depth cm mhos/cm Depth cm mhos/cm Depth cm mhos/cm
0-6(8) 1.30 0-2% 8.20 0-2% 9.15
2%-5 9.00 2%-5 9.50
5-10 9.10 5-10 19.50
10-20 8.90 10-20 51.50
20-30 8.00 20-30 59.00
30-40 6.00 30-40 61.00
40-50 5.50 40-50 34.00
50-60 5.10 50-60 24.00
60-70 4.20 60-70 13.40
70-80 3.90 70-80 12.60
cemented 2.80 80-90 13.20
90-100 10.30 108
" • / m . r 100 zoo 300 400 BOO 600
10
zo
30
40
SO
60
TO
80 Salt Content
Total Cation Concentration
00
IOO 10 Percent Salt
Figure 26* Electrical Conductivity and Total Salt Content by Acid Digestion. portable Orion 404 expanded-scale specific ion meter, A 1:2 soil; water slurry was prepared and stirred for two minutes, with an additional two minutes allowed for stabilization of probes. For each determination, the following standards were used: 1.0M NaCl:100;
0.2M NaCl:20. The relative concentration of Na+ and Cl are presented
in Fig. 27. This method is not sensitive enough to be used on soils with low soluble-salt content such as Alpine I. Low concentrations of chlorine are detectable, but the procedure is only of use in the field when comparing older profiles with definite salt-horizons.
The absence of detectable Na+ in the upper 5 cm of the Alpine III profile (Fig. 27) suggests differential ion-migration rates, when the upper few centimeters of the profile are moistened through infrequent snowfalls. Sublimation and evaporation quickly dissipate the moisture, but some wetting does occur and sodium (ionic radius 0.95 A) could migrate in molecular films of water on soil particles in preference 0 to chlorine (ionic radius (1.81 A).
C. Free Iron Oxides
Ferric oxide minerals, generally called free iron oxides, can be selectively removed from soils and clays. The common minerals constituting iron-oxide coatings with their theoretical compositions are listed in Table 16. Both X-ray amorphous coatings ("limonite") and crystals of free iron oxides (predominantly hematite and goethite) are removed by a dithionite-citrate system buffered with sodium bicarbonate (Mehra and Jackson, 1960). A photosensitive acid ammonium oxalate treatment in total darkness extracts only amorphous iron oxide coatings (deEndredy, 1963; Schwertmann, 1964; McKeague and Day, 1966). 110
ION CONCENTRATION : ALPINE IE
ALPINE
20 20
30 30
40 40
DEPTH cm Cl' N a 50 50
60 60
70 70
8080
90 90
100 J 1----1--- 1100'--- N.R. 20 40 60 8 0 100 N.R. 20 40 60 80 100 RELATIVE CONCENTRATION 20*0.2M NoCI IOO-I.OM NaCI 20 ml H 2 0 10 g SOIL
Figure 27. Relative Ion Concentration: Chlorine and Sodium. TABLE 16. Iron Oxides and Hydroxides
Magnetite Fe+ ^Fe2+ ^0^
Hematite Fe2^3
Goethite -<-FeO*OH (yellow)
Lepidocrocite Tf-FeO*OH (brown)
"Limonite" FeO*OH*nH2C 112 The oxalate and dithionite extracts were made from 0.500 g of cl.ay-.slze material from the soil profiles, and iron in solution was determined by a Perkin-Elmer 303 Atomic Absorption Spectrophotometer. Table 17 presents the amount of extractable iron by each method, and Fig. 28 compares the ratios of oxalate/DCB extractable iron for the chrono logical sequence.
The ratio of oxalate-extractable iron (FeQ) to dithionite- extractable iron (Fe^) provides an index of chemical weathering as a function of time; yellowish iron oxide (limonite) coatings convert to hematite upon aging (Walker, 1967). Berner (1969) contends that finely-divided limonitic goethite is thermodynamically unstable relative to hematite plus water under practically all geological conditions; goethite, in a finely-divided, poorly crystallized form, probably constitutes a major portion of the pigmenting material known as limonite. Examination of mineral particle sizes as well as knowledge of associated temperatures and water vapor pressures must be known before stating the relative stabilities of goethite and hematite in soils (Langmuir, 1970). The premise in oxalate-DCB analyses, however, is that amorphous iron-oxide coatings originally formed by chemical weathering become more crystalline with time; crystalline goethite is not differentiated from crystalline hematite.
Total free iron is more abundant in the Alpine II moraine than in the older Alpine III moraine. I attribute this to the fact that during its formation, the Alpine II moraine was subjected to optimum weathering conditions in the polar desert climate: seasonal meltwater marginal to an ice-cliff. The amount of iron extracted from crystalline TABLE 17. Free Iron Oxides Extracted by Oxalate (FeQ) and Dithionite-citrate (Fe^) Treatments from Clay-size Particles.
ALPINE I ALPINE II ALPINE III Fe Fe Fe Fe Fe, Fe,-Fe o Fe Q Fe H,-Fe i-s o Fe Q o o d d o Fed U U Fed Fed‘Feoa o Depth cm ppm ppm ppm Fe^ Depth cm Depth cm ppm Fed PP™ PPm _ _ Ppm Fed PPm PPm
0-6(8) 3.6 5.4 0.66 0-2% 3.4 3.9 0.5 0.87 0-2^ 2.7 3.5 0.8 0.77
2%-5 3.0 3.7 0.7 0.82 2%—5 2.4 4.0 1.6 0.61
5-10 3.0 4.0 1.0 0.76 5-10 2.4 4.4 1.0 0.55
10-20 4.4 4.9 0.6 0.87 10-20 2.2 4.2 2.0 0.52
20-30 3.8 4.9 1.1 0.78 20-30 2.4 4.0 1.6 0.60
30-40 3.8 4.9 1.2 0.76 30-40 2.4 4.3 1.9 0.56
40-50 4.2 4.9 0.6 0.87 40-50 2.2 4.2 2.0 0.53
50-60 3.8 4.8 1.1 0.78 50-60 2.4 4.5 2.1 0.53
60-70 4.2 5.1 0.8 0.84 60-70 2.7 4.9 2.2 0.55
70-80 4.2 5.0 0.8 0.83 70-80 2.4 4.9 2,5 0.48 Ice- 3.6 4,6 1.0 0.78 80-90 2.2 4.3 2.1 0.50 cemented
90-100 2.4 4.5 2.1 0.53
03 114
20
3 0
4 0
5 0
& Alpine I
6 0
7 0
BO
9 0
0 .5 0 0 6 0 0 . 7 0 0.60 X
Figure 28. Ratio of Extractable Iron Removed by Oxalate and Dithionite-citrate Treatments. hematite and goethite coatings is obtained by the relationship
Fe,-Fe (Table 17). The average percent crystalline-iron over 10 cm d o intervals indicates Alpine III clay particles are coated with about twice as much hematite and goethite as Alpine II clay. The clay-size material in Alpine I, again because of its proximity to the ice-core, is subjected to optimum Pe2°3 + equilibrium conditions; there is nearly as much crystalline iron as in Alpine III samples.
D. Heavy Mineral Analysis
A Frantz Isodynamic Separator was used to determine heavy-mineral concentration of the 0.125-0.105 mm diameter fine-sand fraction.
Mineral identification was based on microscopic examination. All grains within this size range were separated based on mass magnetic susceptibility, Mafic-mineral inclusions in sufficient quantities will cause a grain to be susceptible regardless of its predominant mineral- ogical nature. There is no obvious chemical alteration of individual grains in any separate and there is little or no iron oxide coating.
The stability of iron-bearing minerals is best analyzed by separation based on mass magnetic susceptibility; it is rapid, and separates include similar mafic-mineral suites. Weight-percent composition of four separates is listed in Table 18,
Hand-magnet separation does not provide a reliable estimation of magnetite content because magnetite occurs as inclusions and aggregates as well as individual grains: the abundance of the hand-magnet separate does not serve as a reliable index of weathering. After a sample is cleaned with a small hand-magnet, it is passed through the separator
(side slope 5°, 1.2 amps). These settings are the basis of a light: TABLE 18. Heavy Mineral Separation with the Franz Isodynamic Separator: 0.105-0.125 mm Size-fraction; values represent weight percent,
ALPINE I ALPINE II ALPINE III
Depth cm H.M. N.S. A B Depth cm H.M. N.S. A B Depth cm H.M. N.S. A B 0-6(8) 1.0 49.8 33.1 16.0 0-2% 1.0 45.0 33.0 21.0 0-2% 0.6 53.3 26.5 19.2 2%-5 2.2 41.4 32.6 23.8 2%-5 0.8 53.3 25.0 17.8 5-10 2.6 ------5-10 1.4 45.2 27.7 25.7 10-20 2.7 39.2 39.1 19.0 10-20 0.7 52.2 28.9 18.2 20-30 1.9 42.0 37.0 19.1 20-30 1.0 49.4 29.4 20.2 30-40 1.0 44.3 36.5 18.2 30-40 2.3 48.1 29.1 20.5 40-50 1.8 43.7 36.6 18.0 40-50 1.2 49.7 29.3 19.8 50-60 2.0 ------50-60 0.5 53.6 27.3 18.6 60-70 2.5 41.1 35.8 20.6 60-70 1.0 48.4 31.0 19.6 70-80 1.9 45.2 36.6 16.3 70-80 2.6 46.4 30.5 20.5 Ice-cemented 2.3 42.1 35.6 20.1 80-90 0.9 54.8 26.2 18.2
90-100 2.1 53.2 27.0 17,7 Average Over 10 cm Intervals 2.0 42.6 36.2 19.2 1.3 50,5 28.6 19.5
H.M. Hand Magnet; N.S. Non-susceptible; A Susceptible: II Susceptible at side slope 5°, 1.2 amps side slope 5°, side slope 10°, Nonsusceptible side slope 10:, 0.5 amps. 1.2 amps. 0.5 amps. Fragments and grains with numerous Felsic grains, Mafic grains, inclusions; considered mafic grains. feldspar, quartz, micas, hornblende, minor zircon and pyroxenes, garnet, rutile. accessory heavy minerals. cr> 117 heavy separation. The nonsusceptible fraction is predominantly
feldspar and quartz, with minor zircon and rutile.
The fraction which is susceptible at the first setting is itself
separated (side slope 10°, 0.5 amps). Micas (biotite and phlogopite),
hornblende, pyroxenes, garnet, and other accessory heavy-minerals
(Group A, Table 18) are susceptible, while the nonsusceptible fraction
(Group B, Table 18) is composed of grains with numerous inclusions.
Comparison of weight-percent composition averaged over 10 cm
intervals shows a higher concentration of quartz and feldspar mineral
grains in the Alpine III soil than in the Alpine II soil. The
difference in composition is compensated by increased mafic-mineral
content in the Alpine II soil; the weight-percent of grains with
inclusions remains remarkably constant throughout the sequence of
soils. Labile mafic minerals as inclusions within resistant silicates
(predominantly quartz) are inaccessible to chemical weathering agents
in a cold desert weathering environment.
E. Elemental Analysis by X-Ray Fluorescence
Samples of the very-fine sand (75 to 50 ji) and three fractions
of silt (50 to 20 }it 20 to 5 p, 5 to 2 ji) were analyzed for total Ti,
Zr, Fe, and K by X-ray fluorescence. The samples were mixed with a
binding agent, reagent grade boric acid, in a 7:3 ratio and were
ground for three minutes in a Steib-teckinik grinder to obtain
uniform particle-size and complete mixing. The sample-boric acid mixture was then pressed into briquettes in a hydraulic press at a
pressure of 25 tons/inch . Briquettes were prepared and analyzed in
triplicate. Standards were prepared by the addition method of Handy and Rosauer (1959), and a standard curve was run at the beginning of each elemental analysis. Reference standards were run each hour to check for machine drift.
(1.) Titanium and Zirconium
Titanium and zirconium content of the four size-fractions was determined to obtain a Ti:Zr ratio as an index of lithological uniformity. The most common occurrence of titanium in soils is the oxide: three oxide polymorphs (TiC^) (rutile, anatase, and brookite) and ilmenite (FeTiO^). The weathering product leucoxene, normally finely crystalline rutile, is not recognized in these soils. Rutile and ilmenite are common accessory minerals in igneous and metamorphic rocks, and rutile often occurs as inclusions in other minerals, especially quartz. Zircon (ZrSiO^) is a common accessory mineral of igneous rocks and is often enclosed in later minerals such as biotite and amphibole.
Minerals containing these two elements weather at different rates in a cold desert environment; zircon remains relatively stable whereas titanium can be released from labile minerals. In the cold desert, a Ti:Zr ratio compares titanium content in weakly resistant minerals (magnetite and ilmenite) to titanium and zirconium in strongly resistant minerals (rutile, zircon). Titanium and zirconium concentration is presented in Tables 19 through 22. Table 23 is a composite of the average values of percent composition over 10 cm intervals within profiles. There is no indication of translocation of titanium within profiles, but the Ti:Zr ratio in the upper 5 to
10 cm varies in all grain-sizes. TABLE 19. Elemental Analysis: Titanium and Zirconium, Very-Fine-Sand Fraction: 75-50 p.
ALPINE I ALPINE II ALPINE III %Ti %Zr? %Ti %Zr %Ti XZr„ Depth cm xlO xlO Ti/Zr Depth cm xlO xlO Ti/Zr Depth cm xlO xlO Ti/Zr
0-6(8) 4.0 2.2 18.2: 0-2^5 5.1 4.3 11.8 0-2^ 3.6 2.8 13.0
2^-5 5.4 4.2 12.6 2^-5 3.0 2.3 13.2
5-10 5.5 3.7 14.8 5-10 3.6 3.6 10.2
10-20 6.4 4.9 12.S 10-20 3.6 2.8 12.4
20-30 5.6 4.5 12.4 20-30 4.3 3.7 11.4
30-40 5.2 3.5 14.9 30-40 4.2 3.0 13.8
40-50 5.6 3.9 14.2 40-50 4.0 3.6 11.2
50-60 5.7 4.2 13.4 50-60 3.6 3.2 11.4
60-70 5.6 4,4 13.0 60-70 4.2 4.0 10.4
70-80 5.1 3.4 15.0 70-80 4.4 4.4 10.1
Ice-cemented 5.2 3.6 14.1 80-90 3.6 3.2 11.6
90-100 3j9. 3*4 11,1
Average Over 10 cm Intervals 5.6 4.0 13.7 4.0 3.4 11.5 TABLE 20. Elemental Analysis: Titanium and Zirconium, Coarse-Silt Fraction: 50-20 p.
ALPINE I ALPINE II ALPINE III XTi, 7oZr„ 7=Ti %Zr„ 7oTi. %Zr„ Depth cm xlO* xlO" Ti/Zr Depth cm xlO xlO Ti/Zr Depth cm xlO xlO Ti/Zr
0-6(8) 5.4 2.5 21.2: o-2h 5.7 4.5 12.6 0-2^5 4.7 3.8 12.3
2h-5 6.0 4.4 13,5 2h-5 4.3 3.6 11.7
5-10 606 3.5 18.9 5-10 4.3 4 o0 10.6
10-20 6.6 3.5 18.6 10-20 4.8 3.4 14.0
20-30 6.0 3.2 18.4 20-30 4.2 4.1 10.4
30-40 6.2 3.7 16.6 30-40 4.0 4.2 9.4
40-50 6.2 3.4 18.6 40-50 4.6 3.8 12.1
50-60 6.8 3.6 19.2 50-60 4.6 3.4 13.1
60-70 7.0 3.8 18.4 60-70 4.6 3.7 12.3
70-80 7.4 3.5 21.0 70-80 4„6 3.6 1207
Ice-cemented 6.6 3.6 18.2 80-90 4.4 3.5 12.6
90-100 4.4 3.4 12 c 8
cm Intervals 6.5 3.6 18.4 4.4 3.7 12.1 TABLE 21. Elemental Analysis: Titanium and Zirconium, Medium-Silt Fraction: 20-5 p..
ALPINE I ALPINE II ALPINE III
7oTi. 7«Zr„ 70Ti, 7,Zr? 7„Ti %Zr9 Depth cm xlO xlO Ti/Zr Depth cm xlO xlO Ti/Zr Depth cm xlO xlO Ti/Zr
0-6(8) 5.1 1.5 33.8 0-2% 7.7 1.7 44.4 0-2% 5.4 2.2 25.3
2%-5 8.0 1.6 47.5 2%-5 5.6 2.1 26.3
5-10 7.0 1.6 43.7 5-10 5.3 2.4 22.4
10-20 6.6 1.8 36.4 10-20 4.8 2.4 20.4
20-30 5.6 1.8 31.0 20-30 4.7 2.8 1606
30-40 6.0 1.8 32.0 30-40 4.6 2.8 16.2
40-50 6.2 1.7 35.4 40-50 4.7 2.4 20.0
50-60 6.6 1.7 38.4 50-60 4.6 2.2 20.6
60-70 6.6 1.7 38.8 60-70 4.6 2.4 19.2
70-80 6.6 1.8 35.1 70-80 4.4 2.4 18.2
Ice-cemented 6.4 1.8 36.4 80-90 4.8 1.8 25.6
90-100 4.6 2.1 22.0
ir 10 cm Intervals 6.4 1.8 36.5 4.7 2.4 20.3 TABLE 22. Elemental Analysis: Titanium and Zirconium, Fine-Silt Fraction: 5-2 p.
ALPINE I ALPINE II ALPINE III
y.Tij^ %Zr2 7.TI- 7.Zr? %Ti, 7=Zr Depth cm xlO xlO Ti/Zr Depth cm xlO-1 xlO Ti/Zr Depth cm xlO xlO" Ti/Zr
0-6(8) 5.4 1.0 59.8I 0-21; 8.4 1.1 74.6 0-2% 7.4 2.0 36.5
2*2-5 8.3 1.2 70.0 2*2-5 7.4 1.9 35.4
5-10 8.0 1.2 64.8 5-10 7.0 2.2 31.6
10-20 7.7 1.4 55.4 10-20 6.4 2.2 28.4
20-30 6.8 1.4 46.2 20-30 6.1 2.6 22.6
30-40 7.3 1.5 46.0 30-40 6.0 2.6 22.6
40-50 7.4 1.4 51.1 40-50 6.2 2.3 26.6
50-60 8.1 1.4 57 c4 50-60 6.0 2.1 25.0
60-70 8.0 1.4 59.0 60-70 6.0 2.3 25.5
70-80 7.8 1.4 54.6 70-80 5.8 2.4 23.8
Ice-cemented 7.6 1.4 54.8 80-90 6.2 1.8 35.2
90-100 6.1 2.0 29.9 m CO • cm Intervals 7.6 1.4 6.2 2.2 27.7 122 123
TABLE 23. Summary of Elemental Analysis for Titanium and Zirconium; Average Values, 10 cm Intervals (TABLES 19, 20, 21, 22).
ALPINE I ALPINE II ALPINE III %Ti1 7.Zr %Ti %Zr„ ZTi 7„Zr xlO xlO Ti/Zr xlO xlO Ti/Zr xlO- xlO"
75-50/i 4,0 2.2 18.1 5.6 4.0 13.7 4.0 3.4
50-20/1 5.4 2.5 21.2 6.6 3.6 18.4 4.4 3.7
20-5p 5.1 1.5 33.8 6.4 1.8 36.5 4.7 2.4
5-2p 6.4 1.0 59.8 7.6 1.4 54.8 6.2 2.2 (2.) Potassium
Potassium is present as part of the crystalline structure of micas (principally biotite and phlogopite) and alkali feldspars.
Potassium content of the four size-fractions of the Alpine I sample does not vary significantly from that in the Alpine II profile
(Table 24), and I conclude that there has not been sufficient comminution of sand grains to increase the mica and feldspar content of the silt-size fraction. At depths of 20 to 40 cm in the Alpine II profile, there does appear to be a definite increase in potassium content in the four grain-sizes; mica and feldspar grains are in greater abundance than elsewhere in the profile. Percent composition of potassium in the Alpine III profile is 0.40 to 0.50 percent higher in all size-fractions analyzed than in younger profiles. There is no significant variation in potassium content with depth, however.
As rock fragments and mineral grains disintegrate through physical weathering, the concentration of micas increases in finer particle-sizes; in very old profiles, minerals other than the micas are also reduced in size. Heavy mineral analysis shows an eight- percent increase in the weight of quartz and feldspar in the fine- sand fraction of Alpine III soils (Table 18); in response to this increase, there is a 0.50 to 0.50 percent increase in potassium content in the very-fine sand and silt fractions.
There is also an increase in the fine-grained-mica content of the soils as weathering proceeds, but the small volume does not significantly alter potassium content. The relationship between potassium content in the 75 to 50 p fraction and the weight percent of TABLE 24. Elemental Analysis: Potassium. Percent Composition.
ALPINE 1 ALPINE II ALPINE III in’ o Depth cm 75-50*1 50-20*i 20-5, 5-2*i Depth cm 75-50/1 50-20p 20-5p 5-2*1 Depth cm 75-50*1 50-20*1 i 5-2*i
0-6(8) 1.39 1.64 2.28 2.52 0-21* 1.36 1.53 2.32 2.55 0-2% 1.90 2.18 2.57 3.14
2%-5 1.42 1.64 2.34 2.51 2^-5 1.58 2.10 2.75 3.00
5-10 1.49 1.68 2.36 2.57 5-10 1.82 2.23 2.84 3.08
10-20 1.47 1.79 2.34 2.57 10-20 1.90 2.10 2.70 2.94
20-30 1.62 1.90 2.46 2.68 20-30 1.92 - 2.16 2.80 3.04
30-40 1.63 1.89 2.46 2.66 30-40 1.91 2.16 2.84 3.08
40-50 1.56 1.77 2.36 2.60 40-50 1.94 2.19 2.SO 3.08
50-60 1.48 1.72 2.28 2.56 50-60 1.92 2.12 2.76 3.03
60-70 1.42 1.64 2.16 2.49 60-70 1.95 2.17 2.75 3.06
70-80 1.44 1.60 2.12 2.40 70-80 1.85 2,10 2.72 3.00
Ice-cemented 1.50 1.66 2.24 2.52 80-90 2.08 2.32 2.94 3.16
90-100 1.93 2.22 2.33 3,06
Average Over cm Intervals 1.50 1.73 2.30 2.56 1.92 2.17 2,50 3.05 125 126 magnetically susceptible mineral grains plus magnetite in the L25 to
105 fraction is shown in Fig, 29.
(3.) Iron
Iron content of the size-separates is present primarily in the crystalline structure of silicates (pyroxenes, amphiboles, olivine, micas, and chlorite), oxides (hematite, magnetite, ilmenite, goethite, and limonite (amorphous)), and possibly sulfides (pyrrhotite). The amount of total iron (ferrous and ferric) present as crystalline and amorphous coatings of grains is small compared with the total elemental iron.
There is good correlation between the iron content of the 75 to
50 p size-fraction (Table 25) and the magnetically nonsusceptible weight-percent of the 125 to 105 p size-fraction of the Alpine II soil (Fig, 30). Iron content increases with increasing weight-percent of mafic minerals. The correlation is not as good in Alpine III soil
(Fig. 30) but the fields of points for Alpine II and Alpine III values are mutually exclusive. In all four size-fractions examined by X-ray fluorescence, the iron content of Alpine I soil is comparable to that of Alpine III soil (Table 25).
Iron content in all profiles increases with decreasing grain-size.
Iron-rich accessory minerals released from rock fragments through physical weathering are of smaller grain-size than the host constituents; the iron-rich minerals therefore represent greater proportions of progressively smaller size-fractions. Higher than average iron content in the thawed zone of the Alpine II and Alpine III soils (Table 25) is caused by an increase in iron coatings with 2.5
X Alpine II
O Alpine III 2.0 Percent Potassium 75-50p
1.0 30.0 40.0 Weight Percent Iron-rich Heavy Minerals 125 • 105 p
Figure 29* Potassium Content as a Function of Iron-rich Heavy Mineral Fraction* TABLE 25. Elemental Analysis: Iron. Percent Composition.
ALPINE I ALPINE II ALPINE III Depth 5-2*i Depth cm 75-50*! 50-20ji 20-5*i 5-2ji Depth cm 75-50*i 50-20*i 20-5ji 5-2*1
0- 6(8) 3.19 5.48 0-2Jj 3.63 4.24 5.65 6.78 0-2*2 2.88 3.79 4.56 6.12
2Jj-5 3.84 4.61 5.91 6.66 2*5-5 2.62 3.64 4.68 6.20
5-10 3.78 4.57 5.20 6.40 5-10 2.85 3.65 4.56 6.08
10-20 3.88 4.50 4.86 6.08 10-20 2.95 3.90 4.36 5.81
20-30 3.64 4.42 4.52 5.66 20-30 3.27 3.76 4.47 5.80
30-40 3.59 4.45 4.77 6.00 30-40 3.17 3.62 4.40 5.72
40-50 3.73 4.48 4.70 5.96 40-50 3.12 3.82 4.26 5.55
50-60 3.75 4.60 4.86 6.16 50-60 2.94 3.70 4.12 5.25
60-70 3.78 4.73 4.94 6.26 60-70 3.14 3.84 4.26 5.35
70-80 3.70 4.74 4.76 5.86 70-80 3.24 3.88 4.28 5.26
Ice-cemented 3.66 4.40 4.61 5.68 80-90 2.91 3.66 4.18 5.30
3.04 3.78 4 0 2 5 t32
cm Intervals 3.71 4.54 4.84 6.02 3.06 3.77 .4.31 5.54 128 4.0 r
A Alpine I
* * X Alpine II f * * O Alpine III
Percent
Iron a 7 5 -50)i o 3.0 e o o
o
2.0 I | 40.0 50 .0 6 0 .0
Weight Percent Light Minerals I25-I05p •Figure 30. Iron Content as a Function of Light Mineral Fraction, 129 130 decreasing particle size*
F. Clay Mineral Determinations
Claridge (1960) has produced the most comprehensive examination
of authigenic clay minerals in the ice-free regions of southern
Victoria Land. His findings are summarized as follows:
1.) The dominant process of developemnt of clay minerals is
the slow hydration of micas.
2.) Clay minerals in the most expanded stage are
vermiculite A (hydrated mica) or vermiculite B
(non-collapsing after potassium saturation).
3.) Chlorites may be authigenic.
4.) Some montmorillonite is formed under conditions of
aridity and high pH in environments rich in
calcium and magnesium.
5.) Amorphous material seems to persist under the cold
desert conditions.
6.) The few halloysite tubes observed in electron micro
graphs may result from weathering of feldspars
or glassy volcanic ash.
7.) Clay minerals are actively forming in the Antarctic
environment at the present time.
Tasch and Gafford (1969) examined the weathering products of non-marine shale in the Ohio Range and determined that illite- montmorillonite mixed-layer clay minerals were formed from illite
(stripped form). They made no mention, however, of this weathering
occurring under present conditions. 131 Ugolini (1964) examined three soil horizons in Wright Valley
and found illite, chlorite, swelling chlorite, and kaolinite. He
suggests two distinct stages of formation: a wetter regime responsible
for the most intense weathering, and drier conditions during which salt
accumulated. He considers the weathering cycle to be relict and
suggests that the present conditions for the ice-free areas of Mirny
(Glazovskaia, 1958) are similar to that once occurring in southern
Victoria Land.
Meserve Glacier samples were disaggregated by shaking for
15 hours on a reciprocal shaker in a dispersing solution containing approximately 0.03 g Na^CO^ per gram of soil. Particles 2 p diameter and less were separated and saturated with sodium or magnesium, and oriented diffraction specimens were prepared by the suction-on-ceramic
tile technique (Kinter and Diamond, 1956). Diffraction patterns for
air-dried and ethylene glycol solvated samples saturated with sodium and magnesium were analyzed using CuKp< radiation. Samples were subjected to one-hour heat treatments and X-rayed. Sodium saturated samples were heated at 400°C and 550°C and magnesium saturated samples
at 400°C, On selected samples, iron coatings were removed by the dithionite-citrate method of Mehra and Jackson (1960) and the clay was saturated with magnesium, ethylene glycolated, and X-rayed.
Interpretation of X-ray patterns and clay-mineral identifications are based on the work of numerous authors (e.£., Brown, 1961; Bailey and others, 1967; and Carroll, 1970). The classification of phyllo- silicates follows Brindley and others (1968). Semi-quantitative estimations of clay minerals are determined by a modified method of 132 Johns and others (1954) (Table 26) and are presented in Table 27.
Clay-mineral concentrations are determined by dividing the derived sum
total of all ratios (Table 26; illite ratio = 1) into the ratio
obtained for each mineral species. Quartz and feldspars in the clay- size fraction were not included in the calculations.
Clay-mineral species identified are illite or hydromica,
0 vermiculite, chlorite, interstratified species (expand to about 16.3 A
upon glycolation), and kaolinite. Average clay composition over 10 cm
intervals (Table 27) indicates a higher concentration of interstratified
clays in the Alpine I and Alpine II profiles than in the Alpine III
profile; abundant secondary weathering products are located where water
is now available or where it was available in the past. Large variations in clay-mineral concentration are found throughout each
profile, and there appears to be no translocation of clay once it is
formed. Interstratified clay-minerals are absent in the upper 5 cm
of the Alpine III profile and are rare throughout the upper 10 cm of both Alpine II and Alpine III profiles.
Interstratified and smectite clay-minerals treated with dithionite-
citrate to remove iron coatings will normally expand to a greater
degree upon glycolation. Interstratified iron silicate clays in the
Alpine II profile and at depth in the Alpine III profile, however,
are destroyed by treatment with dithionite-citrate (Table 28). Inter
stratified minerals at depths of 5 to 20 cm in the Alpine III profile
remain after iron-removal treatment, but peak-intensities lowered
considerably. 133
TABLE 26. Semi-quantitative Estimations of Clay Minerals,
Based on planimeter area-measurements of appropriate peaks after magnesium saturation and treatment: ethylene glycol solvation (E.G.), heating (400°C or 550°C).
Clay Mineral Ratio
Illite 10.0-10.2A (E.G.)
16.7-18.0A (E.G.) MontmorilIonite 4x10.0-10.2A (E.G.)
14.0-14.7A (E.G.) - 14.0-14.7A (400°C) Vermiculite 2x10.0-10.2A (E.G.)
14.0-14.7A(400°C) Chlorite 2x10.0-10.2A (E.G.)
3.5A (400°C) - 3.5A (550°C) Kaolinite 4x10.0-10.2A (E.G.)
Interstratified 10.2-14.0A (E.G.) (10.5-13.8A) 2x10.0-10.2A (E.G.)
Interstratified 14.7-16.7A (E.G.) (14.7-16.7A) 4x10.0-10.2A (E.G.)
Only the clay-mineral-species content was determined; quartz and feldspar were also present in the clay-size fraction. To compute relative clay-mineral percentages, the sum total of all ratios (illite ratio = 1) is divided into the ratio obtained for each mineral species. TABLE 27. Semi-quantitative Clay Mineral Concentration
ALPINE I ALPINE II ALPINE III Percent Concentration (+5%)* Percent Concentration (+57.)* Percent Concentration*(+57.) Depth cm II I.S. Ve Cl Ko Depth cm II 1.5. Ve Cl Ko Depth cm II I.S. Ve Cl Ko
6(8) 33.2 21.6 29.4 12.0 3.6 0-2^ 55.2 7.2 23.7 12.2 1.5 0-2^ 53.0 ---- 31.3 12.0 3.6 2^-5 45.1 12.7 25.6 14.2 2.2 2^-5 48.9 tr 14.4 30.0 6.6 5-10 47.7 14.6 26.5 9.8 1.3 5-10 61.5 4.6 9.2 21.5 3.0 10-20 48.7 14.0 15.4 15.4 6.4 10-20 56.2 7.0 8.6 23.8 4.2 MESERVE CORE 20-30 46.4 17.0 23.2 10.6 2.6 20-30 67.6 7.8 10.2 12.2 1.8 Percent Concentration (+57.)* 30-40 48.0 13.0 24.0 10.0 5.0 30-40 36.2 6.2 48.6 7.4 1.6 11 I.S. Ve Cl Ko 40-50 30.1 18.8 37.6 8.6 4.8 40-50 69.4 2.9 12.7 12.7 2.2 60.3 ---- 9.6 9.6 20.5 50-60 39.6 16.6 32.5 7.9 3.2 50-60 54.2 5.2 24.0 12.4 4.1
60-70 29.9 22.4 28.8 15.0 3.7 60-70 52.7 6.9 18.6 17.0 4.6 70-80 41.0 14.6 30.2 11.7 2.4 70-80 44.8 8.4 38.3 4.6 3.7 Ice-cemented 36.0 18.0 27.5 14.8 3.6 80-90 46.3 5.4 29.9 14.6 4.2 90-100 59.6 _8.,4 21.7 7.4 2,6
Average Over 10 cm Intervals 41.0 16.3 27.2 11.7 3.7 54.4 6.0 22.8 13.4 3.4
* II: illite; I.S.: interstratified (14.7-16.7A expansion on glycolation); Ve: vermiculite; Cl: chlorite; Ko: kaolinite. 135
TABLE 28. Interstratified Mineral X-Ray Diffractogram Analysis: Glycolated after Removal of Iron Coatings.
ALPINE II ALPINE III Depth cm Untreated Fe Removed Depth cm Untreated Fe Remove*
0-2*8 7.2% None 0-2% None tr.
2%-5 12.8% None 2%-5 None None
70-80 14.6% (->* 5-10 4.6% (--)*
cemented 18.0% None 10-20 7.0% <--->*
20-30 7.8% (— )*
30-40 6.2% None
40-50 2.9% None
50-60 5.2% None
* Indicates peak intensity relative to untreated peak intensity: (-) = lower, (— ) = much lower, (---) = very much lower. CHAPTER VI
CONCLUSIONS
A. Present Weathering Processes in the Wright Valley CoLd Desert
(1.) Physical Weathering
Kelly and Zumberge (1961) stress the importance of physical processes and minimize the effect of chemical reactions at Marble
Point. The physical disintegration of rocks is accomplished by the growth and expansion of crystals of salts, wind abrasion, volumetric expansion due to temperature rises, and frost action. Salt weathering is the most effective and is very intense throughout Wright Valley.
Selby and Wilson (1971) attribute the formation of Labyrinth (Fig. 2) to salt weathering, and Selby (1971) has outlined its effect in landform development. Salts confined in pores and fissures in rocks undergo three major types of change in creating stresses which may lead to rock disintegration: (1) growth of crystals from solution;
(2) thermal expansion; (3) hydration (Cooke and Smalley (1968).
Non-porous and unfractured rocks are least affected by salt weathering and frost action. Experiments on pebbles covered with saline efflorescence (Birot, 1954) show disaggregation is aided by rough, cracked surfaces, with physical rather than chemical breakdown predominating over short time-periods. In Wright Valley, wind- polished surfaces and boulders sealed by desert varnish are immune to 137 salt weathering (Selby, 1971).
The disintegration of boulders alters the lithology and the particle-size distribution of the upper 5 cm of Alpine III soil
(Table 13b). Non-porous dolerite boulders undergo disintegration along fractures, increasing the amount of resistant pebbles and cobbles on the surface, while porous and highly fractured rocks are reduced to gravel, pebbles, and coarse sand-si2e particles.
Wind erosion from moraine crests continues as upstanding boulders are lowered until before a desert pavement is formed. Under present conditions, there is little wind erosion of either the Alpine III or
Alpine II surfaces on the east side of Meserve Glacier; the former is too old, the latter too young. There is no way of determining how much wind erosion of moraine crests has occurred, but I doubt if the surface has been lowered more than 10 to 20 cm. Following comminution below sand-size, fragments from totally disintegrated boulders are removed from the moraine crest by the wind; large boulders planed to the surface cannot be reconstructed from surrounding pebbles of the same lithology (Fig. 31).
If salt weathering is occurring at depth in the Alpine III soil profile, it does not create recognizable particle-size differentiation
(Appendix A). There is, however, a marked increase in percent very- coarse- and coarse-sand in the upper 5 cm of the Alpine III profile due to physical weathering of surface boulders and pebbles.
Average sand, silt, and clay composition of Alpine II and
Alpine III profiles are nearly identical, although there is a slight increase in silt and clay composition at the expense of the sand Figure 31. Metasediment Boulder Planed to Surface of Alpine III Moraine, East Side, Meserve Glacier. 139 fraction in the Alpine III profile (Fig. 22). The slight increase in
fine clay at depth in Alpine III soil is probably a result of chemical
reactions rather than winnowing (Fig 23).
The apparent absence of clay illuviation in both Alpine III and
Alpine II profiles implies that neither has been subjected to frequent
dessication-rewetting cycles. The Alpine II profile is partially
saturated by refrozen ground water, but there is no evidence of the
Alpine III profile having been similarly saturated.
I believe the similarity of some physical and chemical weathering criteria of Alpine II and Alpine III profiles to be a result of differential exposure to meltwater. The crests of all Alpine II
lateral moraines are presently isolated from the ice-cliff (Fig. 13),
The depression between the crest of Alpine II laterals and the ice- cliff is being altered by sheet-flood as dry-calved ice blocks and wind-drifted snow banks melt during the summer and marks the base of
the proximal slope of the moraine ridge.
A series of Alpine II recessional moraines in front of the small unnamed glacier west of Bartley Glacier (Fig. 5) indicates
Alpine II deglaciation was a relatively slow process with intermittent still-stands. During Alpine II deglaciation, therefore, the ice-cliff of Meserve Glacier was much closer to the lateral moraine than it is at present, and meltwater saturated the crest of the Alpine II lateral moraine. Initially, meltwater may have followed the bedrock channel between the Alpine III and Alpine II lateral moraines (Fig. 11).
Eventually, however, meltwater was confined to a small channel between the two prominent ridges on the crest of the moraine (Fig. 11) and 140 between the moraine and the ice-cliff.
I interpret the ice-cemented layer at depth in the Alpine II profile to represent refrozen meltwater which saturated the profile each summer. The water entered the moraine laterally as ground water rather than vertically through the profile from the surface. I find no evidence that silt and clay were washed from the upper portion of the profile and deposited in or near the present ice-cemented layer.
The ice-cemented layer has been subsequently lowered through sublimation.
Only one Alpine III recessional moraine is exposed marginal to alpine glaciers in Wright Valley. It is on the east side of Meserve
Glacier and is partially covered by the multiple Alpine II lateral moraine. I believe that margins of Meserve Glacier responded rapidly during deglaciation from the Alpine III maximum position, Alpine III ground moraine or recessional moraines may be buried beneath the prominent Alpine II deposits. The Alpine III lateral moraine now exposed was not subjected to meltwater saturation as was the Alpine II moraine, and the physical and chemical weathering criteria are based on the time factor rather than anomalous moisture conditions.
The surface weathering criteria (Appendix A) of the Alpine Ila moraine place its age as intermediate between that of Alpine III and
Alpine II moraines. This moraine may be indicative of a separate
Alpine Glaciation but is most probably a phase of the Alpine II
Glaciation. It has been altered by meltwater and I have found a buried paleosol covered with 10 to 30 cm of well-sorted gravel and sand. I believe this moraine surface was covered with meltwater during summers as the Alpine II crest formed. This seasonal wetting 141 accounts for the intermediate surface weathering criteria.
Physical weathering criteria prove useful only for local areas with similar depositional histories and close lithologic control.
Criteria from lateral moraines on the east side of Meserve Glacier are distinct from those on the west side (Appendix A) because of abundant volcanic rocks and Ferrar Dolerite on the west side. The
Alpine II looped end-moraine contains lithologies peculiar to each side, but internal chaotic bedding suggests a depositional history much different from the homogeneous-till deposition forming the lateral moraines.
Statistical analyses of upstanding and weathered surface boulders are applicable to individual moraines, but correlation between moraines must be done with extreme caution. On the east side of Meserve Glacier, an average of 42 upstanding and planed boulders were counted in circles 20 m in diameter described on the crest of Alpine III moraines; there were more than 112 on the crest of Alpine II laterals
(Appendix A, sum of A + B).
Variations in wind intensity and duration cause anomalous rates of boulder planation and must be considered when comparing physical weathering criteria. Air masses moving through the valley, for example, are channeled up and over the prominent Loop end-moraine and not one boulder remains upstanding on the crest. High-velocity winds constantly scour the surface and the moraine crest appears to be older than its chronological position in the sequence of glaciations.
Comparison of resistant lithologies at the surface with those at depth beneath the zero-degree isotherm is the most reliable physical 142 weathering criterion. It is independent of density or numbers of boulders in the drift, and it can be applied to moraines of all alpine glaciers and most axial ice-advances.
Satisfactory comparisons of quantitative physical weathering criteria are limited to closely adjacent moraines of the same ice- advance in Wright Valley. Variations in climate and lithologic differences are the limiting factors of temporal differentiation by surface appearance in the cold desert. The failure of physical weathering criteria for temporal differentiation over large areas is not peculiar to cold deserts, as Sharp (1969) described similar spatial restrictions in a more temperate climate near Convict Lake,
Sierra Nevada, California.
(2.) Chemical Weathering
Numerous authors attribute the presence of salts on and within soils in the ice-free valleys of the McMurdo Sound area to chemical weathering (£.£., Gibson, 1962; Claridge, 1965; Tedrow and Ugolini,
1966; Campbell and Claridge, 1967; McCraw, 1967a; Claridge and Campbell,
1968; Jones, 1969; and Linkletter, 1971). Other authors, however, suggest an aerosol origin for the salts (£•£•> Wilson, 1970; Dort,
1970).
Geochemical investigations in Wright Valley by Jones and Faure
(1967) and Jones and others (1967) show chemical weathering occurred at some time in Wright Valley, but the question of active chemical weathering under present climatic conditions remains. Jones (1969) 87 86 determined the Sr /Sr ratios of water-soluble salts in moraines of
Meserve Glacier and found them to be similar to the ratios of the 143 parent material (Table 29); she concludes the salts were formed in situ through chemical weathering. Jones (personal communication) considers the strontium in Lake Vanda to have been derived from chemical weathering of bedrock in Wright Valley. The chemical similarity between Ca and Sr dictates that calcium is also mobilized through weathering, as the Ca/Sr ratio in Lake Vanda compares favor ably with the Ca/Sr ratio in the "average" Wright Valley bedrock.
Analyses of snow and ice from several localities in Wright
Valley and at South Pole Station show that much salt is distributed as aerosols (Table 30). The chlorine found within the Alpine III soil was not derived through chemical weathering nor does there appear to be an available source for sulfur. There is very little pyrite in the various size fractions, and no pyrrhotite was identified. The sulfate in the soils must have originated as aerosols. I conclude that salts within the Meserve Glacier chronological sequence of soils were derived primarily from aerosols. The largest concentrations are in the oldest soil of the chronological sequence, yet this soil is apparently the least chemically weathered by most criteria. Salt accumulates from infrequent precipitation and is translocated very slowly to the maximum depth of diurnal temperature fluctuations during the austral summer.
Ferric oxide minerals which coat most silt- and clay-size grains in all soils of the chronological sequence are derived from minerals of the heavy mineral suite. The low concentrations of mafic minerals in the Alpine III profile, however, does not correspond to increased iron-oxide coating of the clay fraction (Fe^, Table 17; and A, Table 18). 87 88 TABLE 29. Sr /Sr Ratios of Water-Soluble Salts and Total Salt-free Soil, and the Lithologic Composition of Moraine Samples, Meserve Glacier, Wright Valley. (After Jones, 1969)
„ 87 /e. 86 a 87 y 86 a Sample depth Sr /Sr Sr /Sr Percent Pebble Composition ^ (cm) salt salt-free soil basalt dolerite basement
WVM-1 (2-4) 0.7121 0.7127 0.0 100.0 0.0
WVM-2 (5.5-27.5) 0.7146 0.7152 0.0 6.2 93.8
WVM-6 (3-16) 0.7137 0.7137 0.0 5.2 94.3
WVM-8 (2-12.5) 0.7130 0.7138 5.2 7.7 87.1
WVM-9 (2-12) 0.7145 - 2.2 2.0 95.8
WVM-19 (15-20) 0.7091 0.7046 89 10 1
WVM-22 (8-28) 0.7080 • 77 C 20 ° 3 C (106-109) 0.7066 0.7047 d d d
WVM-23 (2-9) 0.7142 _ 9.9 13.8 76.3 (9-19) 0.7142 - 15.0 6.1 78.9
WVM-24 (9-36) 0.7157 - 0.0 12.7 87.3
MAB 0.7099 0.7107 34.3 65.7 0.0 87 86 Sr /Sr : Average for bedrock in Wright Valley - 0.715; Basalt - 0.7040; Dolerite - 0.7123; Olympus Granite-gneiss - 0.7170; Vida Granite - 0.7169. cL 86 88 k Corrected for fractionation assuming Sr /Sr = 0.1194. d Pebbles greater than k inch diameter. C Pebble count approximate. Pebble count not available at present time; sample highly indurated; basalt with some dolerite. 145 Clay minerals in the Alpine II profile are coated with greater
amounts of iron oxide than clay in the Alpine III soils because there
is more total iron in the very-fine sand and the silt-size fractions
(Table 25). The smaller-sized particles are most susceptible to
chemical weathering.
I believe that the marked difference in heavy mineral concentration
between the Alpine III and Alpine II profiles results from a difference
in parent materials. The climate in Wright Valley after the valley-
cutting glaciations and prior to the Alpine III Glaciation could have been warmer than the present climate. It is postulated that the
heavy minerals in the sand- and silt-size fractions of exposed material were lost through chemical weathering. This weathered material along with unweathered bedrock was incorporated into moraines
during the Alpine III Glaciation. The material forming the prominent
Alpine II lateral moraines was created from unweathered bedrock,
Alpine III ground moraine, and minor volcanic rocks. The volcanics
and fresh bedrock increased heavy mineral content in the Alpine II
till.
A difference in parent materials may also account for the
anomalous grain surfaces in the 0.125 to 0.105 mm particle-size
range. Grains of hand-magnet separates were examined with a
reflecting microscope, and grain-surface variations were found between
soils of the chronological sequence. Extremely corroded crystals of
magnetite and perfect, uncorroded crystals are present in the Alpine III
soil. The surfaces of magnetite grains in the Alpine II and Alpine I
profiles are at least slightly etched, and most are moderately 146
TABLE 30# Partial Chemical Analyses of Snow and Ice: Wright Valley and South Pole Samples#
Wright Lower Glacier Meserve Glacier South Pole a Angino and others, surface nev£ and ice Wilson and House, 1964 HoIds worth, 1969 1965
2 ppm ppm ppm g/cm annual infall
Cl 14 — 0.027 2 x 10"7 b
K 4 0.2 - 0.5 0.007 5 x 10-8 b
Na 6 0.55 0.013 10-7 b
Ca 7 0.33
Mg 1 — — - ---
SO, 0
Altitude 2700 m, 1600 km from the ocean in summer, nearly twice as far in winter. b Marine origin.
Ice below the ice-fall, Wright Upper Glacier: 0.2 ppm total salt.
Wilson, 1968, letter to C. Bull. 147 corroded (Table 31).
The presence of magnetite crystals may result from:
(1) authigenic formation; (2) release from larger mineral aggregates through physical comminution; (3) isolation from chemical reactions by silt or clay coatings. Soil pH conditions and laboratory Eh values, if they truly represent the actual iri situ conditions, indicate magnetite and water are unstable and the magnetite cannot be authigenic
(Garrels, 1960).
Active physical weathering is presently confined to horizons containing moisture or in close proximity to a source of moisture.
Magnetite grains 0.125 to 0.105 mm in diameter freed from a larger aggregate would have been etched by chemical reactions during comminu tion or shortly thereafter. All magnetite crystals in horizons of maximum chemical alteration under present conditions are corroded.
I feel that magnetite crystals were deposited within the Alpine III moraine with protective silt or clay coatings, and they remained unaltered because the profile was not subjected to water-leaching.
Under the apparent in situ Eh-pH conditions, leaching would cause translocation of iron in the reduced ferrous state. Titanium would also have been released under more severe weathering conditions, but there is no indication of titanium having been translocated within the profile (Tables 19, 20, 21, and 22). Titanium released by weather ing in cold desert soils is not very mobile; the high pH environment and dehydration of titanium hydroxides results in formation of one of the crystalline polymorphs of Ti02» Leucoxene coatings on very-fine sand grains are not visible but these grains were also relatively free 148
TABLE 31. Examination of Surfaces of Magnetite Crystals.
Nearly uncorroded Spherical Corrosion* Crystals_____ Magnetite
Alpine I
WVMC 6 0-6(8) M
Alpine II
0-2*s M 2*5-5 M 5-10 M, S 10-20 M, S 20-30 E, M 30-40 M, S 40-50 M, S 50-60 M, S 60-70 M, S S 70-80 M, S S cemented M, S S
Alpine III
0 -2 ^ E , M, S 2*5-5 Ef M, S 5 -10 E , M, S S 10-20 E, M, S 20-30 E, M, S S 30-40 E, M, S S s 4 0 -5 0 E, M, S S s 50-60 E, M, S S 60 -7 0 E , M, S S 70-80 E , M, S s 8 0 -9 0 E , M, S S s 90-100 E, M, S s
*E - extreme M - moderate S - slight 149 from iron stains. Zirconium concentration of size fractions is most
uniform in the Alpine III soil (Table 23) as a result of physical
comminution of accessory minerals prior to incorporation in Alpine III moraines. Titanium/zirconium ratios are inversely related to particle
size: the smaller the size-range, the higher the ratios (Table 23).
The potassium content within cold-desert soil profiles does not
change appreciably with time for two reasons: (1) water does not leach
through the soil; (2) silicates, such as muscovite and potash feld
spars, are quite resistant to chemical breakdown. Some potassium is undoubtedly released from micas when the saline environment is moistened, but it is susceptible to fixation by clay mineral structures.
Potassium is not lost from cold-desert soil systems and the potassium
content with depth for a particular size range remains constant
(Table 24). Potassium concentration varies with particle-size due to
particle-size of parent materials and comminution of rock fragments.
(3.) Authigenic Clay Minerals
Under present cold desert conditions, weathering of soils marginal to Meserve Glacier is forming and altering clay minerals.
Unweathered parent material (till) has not been found in Wright Valley.
The Meserve Core material may in part be "unweathered" till but it is
predominantly ground bedrock beneath the drill hole and is not representative of soil parent material. The analysis of clay minerals
from the core sample (Table 26) indicates a lack of expandable species.
The abundance of kaolinite in the Meserve Core sample certainly
suggests that it originates in part from the bedrock; Claridge (1960)
suggested this possibility. 150 Jackson and others (1952) propose a layer-silicate weathering sequence as follows:
Mica illites "intermediates" -ss— vermiculite montmorilIonite.
This sequence was later expanded by Jackson (1963):
Mica Pedogenic Biotite Vermiculite MontmorilIonite 2:1-2:2 swelling Muscovite 18 A Illite intergrade
(Fe, Mg, Al) Secondary Pedogenic A1 Kaolinite and Chlorite — =- Chlorite — =** 2;l-2:2 — =*- Chlorite — ^ Halloysite. 14 A intergrade
Aluminum released by weathering is deposited in 2:1-2:2 intergrades with aluminohydroxyhydronium (Al^OFO^t-O^)^*^) (Jackson, 1963).
This polymeric cation in part balances the charge resulting from depotassication and causes the formation of 2:1-2:2 pedogenic forms.
The interstratified species (I.S., Table 27) identified in soils of the Meserve Glacier region expand on glycol solvation to about
0 16.35 A : they are not montmori1Ionites. The true nature of the interstratified species may be represented by a "swelling chlorite", where Mg(OH)^ is "precipitated" in a discontinuous manner resembling brucite "islands" allowing channels for passage of ethylene glycol
(Brown, 1961).
The following generalizations can be made of the present weathering conditions in Meserve Glacier soils:
(1) Mica (biotite, phlogopite, and hydromica (illite))
weathers to vermiculite in "wetted" horizons.
(2) Chlorite is present as a primary mineral in bedrock and
as authigenic species through the alteration of 151 biotite, hornblende, and other minerals.
(3) Interstratified clay minerals of the swelling chlorite
type or Jackson's Pedogenic Intergrade are the
weathering products under present conditions.
(4) Kaolinite (halloysite) may be authigenic under low pH
conditions at surfaces of oligoclase and plagio-
clase grains but is unstable due to high
| j concentrations of Mg and Ca .
(5) Authigenic kaolinite, and kaolinite released from bed
rock through comminution of particles, is altered
to X-ray amorphous hydrous alumino-silicate
(allophane).
The principal authigenic clay minerals in the soils studied are
interstratified species, vermiculite, and chlorite. Insufficient
information is available to interpret the frequency and degree of
association of multi-component interstratification. The greater
abundance of these minerals in the Alpine II and Alpine I profiles
(Table 27) is a result of the availability of moisture or water
vapor. Pedogenesis in the Wright Valley cold-desert is not at present
an open system, as basic cations and silica are not being removed.
Reactions are probably reversed by a build-up of a high concentration
of constituents normally removed by leaching (Jackson, 1968), and if montmorilIonite were once present, it would be altered to some
pedogenic intergrade.
Weathering reactions in more temperate climates occur at solid-
liquid interfaces. In the cold-desert climate, however, weathering 152 may be initiated or even controlled by a solid-gas reaction (Wayman,
1963). Little is known of these reactions but the diurnal "air-pump" in the Meserve soils causes gaseous exchange of water vapor and carbon dioxide between the atmosphere and the soil.
B. Relative Ages of Alpine Glaciations of Meserve Glacier
Physical and chemical weathering reactions in the chronological soil sequence on the east side of Meserve Glacier are multivariate functions, but total salt-content may approach a univariate function.
The relative ages of Alpine II and Alpine I moraines in Table 32 are based on the following assumptions: (1) the source of all salt is through precipitation, (2) average annual precipitation at profile sites has remained constant, and (3) salt has not been leached from the one-meter profiles examined; salt-content in the chronological sequence of soils is a time-dependent linear function.
Two linear equations of salt concentration as a function of time are possible: the first is based on salt-content of one-meter profiles, the second on salt-content of the entire profile to bedrock. Salt- content of one-meter profiles is expressed as total cation concentra tion (me/liter) for 10 cm sample horizons (Fig, 26). The amount of salt below a depth of one meter in the Alpine II moraine, about 19 m thick, and the Alpine III moraine, about 12.5 m thick (Fig. 13), must be estimated (Table 32).
Reaction kinetics (Laidler, 1965) applied to selected chemical- weathering criteria provide a check of relative age determinations of the Alpine Glaciation chronological sequence. First order reaction equations have been applied by many authors under other climatic TABLE 32a. Relative Age Estimations Based on Salt Concentration and Reaction Kinetics.
f L (s, t) f2 (s, t) Salt content Estimated Salt Reaction Kinetics; Potassium Composition in Profile Content, Surface to Bedrock * 75-50u______50-20p______20-5p______5-2p
Alpine I 4.4 x lO'V 5.2 x 10^y 6,6 x 10^y 6.7 x 10^y 6.0 x 10^y 5.9 x 10^y
Alpine II 2.45 -,.2.60 2.20 -g2.30 7.1 x 10**y 6.0 x 10^y 3.2 x 10^y 2.4 x 10^y x 10 y x 10 y
Absolute date by K-Ar method:
Alpine III 2.5 -,3.4 2.5 - 3.4 x 10 y x 10 y
Age assumed for calculations: 3.0 x 106y 3.0 x 106y 3.0 x 106y 3.0 x 106y
* Assuming linear decrease of salt content from one-meter depth to zero concentration at bedrock- moraine interface. Estimations based on Ficks' Law of Diffusion and uniform concentration below one-meter depths do not vary significantly from and f^ values. TABLE 32b. Relative Age Estimations Based on Potassium Composition and Reaction Kinetics.
Potassium Composition in Very-fine-sand and Silt Fractions
75-50u 50-2011 20-5n 5-2n
C b 1,389 1.639 2.279 2.519 o Alpine I 1.39 1.64 2.28 2.52 (0-6(8) cm)
Alpine II ' (1.39) (1.58) 2.33 a (2.53) (0-5 cm)
Alpine II 1.50 a 2.14 a (2.30) 2.56 a (Average)
Alpine III (1.74) 2.14 a 2.81 8 3.07 8 (0-5 cm)
Alpine III 1.92 8 (2.17) (2.80) (3.05) (Average)
Rate Constant (b) 4.686 x 10"8 3.852 x 10-8 2.980 x 10“8 2.864 x lO-8
Values used to calculate relative ages, Table 32a, b C has been arbitrarily chosen to allow for a calculation of the age of the Alpine I soil there has been little alteration in potassium composition in the Alpine I soil since formation. conditions to determine relative age: RusselL (1962), organic matter;
Olson (1958), carbonates; and Ruxton (1968b), devitrification of glass in volcanic ash deposits. Alexander (1970) has investigated orders higher than one on a variety of criteria.
The rate of a reaction dependent on one reactant is
(6 .1) where
t = time
C = concentration of reactant
k = rate constant
n = order of equation.
The general solution is
while the solution for a first order reaction ( n=l ) is
-kt C = C e (6 .2) o where CQ = concentration of reactant at time zero ( t=0 ).
Logarithmic transformation of the first order reaction-rate equation converts (6.2) to linear form:
log C = log Cq + bt (6.3) where k b 2.3026 . 156 The only soil property showing consistent trends in the chrono logical sequence is the elemental potassium content of very-fine-sand and silt. First order rate equations and relative ages were computed for this reaction (Table 32).
Summary
With appropriate assumptions, the relative ages of Alpine
Glaciations can be obtained by soil salt-content, A check on these ages is possible through first order reaction kinetics of elemental potassium content, with best results obtained from medium- and fine- silt fractions. The methods provide supportive evidence for placing the Alpine II Glaciation between 2,4 and 3.2 x 10^ years B.P., and the 3 Alpine I Glaciation between 4.4 and 6.0 x 10 years B.P.
Application of these relative dating techniques to all glacial events in Wright Valley will establish a more precise glacial sequence. The acid oxalate to dithionite-citrate extractable Fe ratio does not show a consistent trend in soils of the Alpine Glaciation chronological sequence because of variations in substrate and moisture in the profiles. It should, however, be a useful quantitative temporal property of Axial Glaciation soils to which reaction kinetics can be applied.
C. Implications to Axial-Alpine Glaciation Relationships
(1.) Introduction
One of the principal aims of this original work was to develop methods of determining the relative age of deposits by the stage of weathering. I have now completed field work in mapping the soils throughout Wright Valley and have collected a suite of samples 157 representing the complete glacial sequence as determined by Calkin and others (1970) (Fig. 8). Laboratory analyses of these samples are not completed. A revised sequence of glaciations in Wright Valley, with relative ages determined by this weathering study, is presented in Table 33.
(2.) Axial Glaciations from the West
As previously mentioned, Axial Glaciations from the west are difficult to correlate with other glaciations because there is no obvious interrelationship with Alpine Glaciations. There is one high-level cirque in the Asgard Range, due south of Lake Vanda and west of Mt. Odin (Fig. 4), from which there has been minor alpine ice-advance, but the ice-tongue never was large. Soils on deposits of Wright Upper III Glaciation in the South Fork appear in the field to be similar in age to Alpine II soils at Meserve Glacier. There are numerous upstanding boulders and an ice-cemented layer about one meter below the surface. Stagnant-ice features are abundant in the South
Fork, but there is little evidence of this ice-advance in the North
Fork; older weathering surfaces have been overrun and planed-off, but not buried. Similar conditions are postulated for the Alpine III lateral moraines of Meserve Glacier below about 900 m elevation.
Weathering of Wright Upper III glacial deposits appears to be at the same stage as weathering of Trilogy moraines near the terminal position (Fig. 8). Indeed, Wright Upper III and Trilogy ground moraines are similar in many respects: stagnant-ice features, anomalous saline ponds or salt flats, and surface weathering which gradually decreases in intensity with proximity to the present ice-front. TABLE 33. Revised Glacial Sequence Based on Weathering and Soil Studies
Wright Upper I -— -- ■ Alpine-,1 ---- — — Wright Lower Wright Upper II ----- (a x l — Trilogy Wright Upper III— — ? ■ Alpine,-II----- (b x 10 yr) — Loop ■ Alpine Ila or ----- Mudflows and Fans Wright Upper IV — -- ■ Alpine,III 1 Pecten (c x 10 yr) Valley-cutting episodes 159 Wright Upper IV ground moraine is exposed between the east end of Dais and the east end of Lake Vanda (Fig. 8). Weathering of the surface is not uniform; soils in the vicinity of Canopis Pond appear to be significantly younger than soils on ground moraine south of the peninsula in Lake Vanda. Numerous upstanding boulders are present in the vicinity of Canopis Pond, yet there are also boulders weathered to the surface. I suggest two possible explanations: Wright Upper III ice extended about 2 km further east than is shown in Fig. 8, and boulders from Dais were carried on or in the thin ice-tongue and deposited on an older (Wright Upper IV) surface. These deposits could also represent a separate glaciation older than Wright Upper III but younger than Wright Upper IV. The oldest Wright Upper IV soil does not appear to be as old as Alpine III soils at Neserve Glacier; laboratory analyses are required to determine the exact age relationship between the two soils. I do not believe Wright Upper IV soil represents a weathering surface since the valley-cutting stage 4.0 m.y. ago: it is definitely younger than soil on Pecten deposits and the Pecten Glaciation definitely post-dates valley-cutting stage(s), (3.) Axial Glaciations from the East Soil on Pecten ground moraine is possibly older than Alpine Til soil at Meserve Glacier. Pecten ground moraine is characteristically silt-loam, with a very low coarse-fraction content. The texture and color (10YR7/2 - 7/3: light gray to very pale brown) of Pecten till is unique; the only other deposits which resemble the less than 2 mm fraction of the till are slack-water silts and/or aeolian silts. 160 Everett (in press) has suggested that similar soil (WVM 24, Fig. 9) is older than Alpine III soil. The extractable iron procedures and analyses of the heavy mineral suite should resolve this problem. Soils on lateral moraines of the Loop Glaciation are protected from contin uous wind erosion and are similar to Alpine II soils at Meserve Glacier. If an ice-cemented layer is present, it is more than 120 cm below the surface at an elevation of about 350 m. Salt is present both as free crystals and as encrustations beneath pebbles, but this soil is form ing under the influence of greater precipitation than soils at Meserve Glacier less than 5 km to the west, I tentatively place Loop Glacia tion older than Alpine II but not by more than a factor of two (Table 33). Soils of Trilogy age are forming over an ice-core or an ice- i cemented layer. The terminal position is approximately 2.5 km east of the prominent Loop end-moraine (Fig. 4). Except for a gradual decrease in depth to ice-cemented permafrost, there is no significant change in Trilogy soil to within 50 m of the present Wright Lower Glacier. I do not believe the Wright Lower Glaciation was as extensive as shown in Fig. 8. Soils in Trilogy deposits are younger than Alpine II soils at Meserve Glacier. Laboratory procedures should establish how much younger, but field examination suggests a factor of one-half. Wright Lower Glaciation cannot be differentiated from Alpine I soil at Meserve Glacier except for the presence of an occasional boulder which is partially cavemously weathered. I believe that the youngest axial glaciation from the east advanced no more than 50 m beyond the present ice-margin just prior to the Alpine I Glaciation. (4.) Alpine Glaciations Characteristic soil profiles at Meserve Glacier apply to Hart and Bartley Glaciers as well. The Alpine III moraine is not prominent at Goodspeed Glacier. The unnamed glacier west of Bartley Glacier formed numerous recessional moraines during deglaciation from maximum Alpine II position. The soils developed on the recessional moraines appear to provide the most complete sequence of Alpine II Glaciations: they are all older than Alpine I at Meserve Glacier. The complete Alpine Glaciation sequence is not exposed at Clark and Denton Glaciers at the east end of Wright Valley because the Loop Glaciation covered or reorganized older alpine deposits. A buried paleosol is present at the east end of the valley; 22 cm of Trilogy till overlie a highly weathered Loop or older surface. The buried soil is deeply weathered, has a strongly indurated salt horizon, and is iron-stained. Laboratory analyses will determine the provenance of the till and its identity. (5.) Variations in Weathering Rates in Wright Valley There are many factors which influence the weathering of the chronological sequence of glacial deposits in Wright Valley. Lithology of parent material varies and the climate is not the same everywhere in the valley. The most important consideration in examining weathering processes in this cold desert is the variation in climate throughout the valley, specifically precipitation differences. During my three field seasons I have observed the summer precipitation conditions and general climate described in Table 34. Lithologic differences may be generalized as follows: Beacon TABLE 34, Field Observations of Present Summer Climate Conditions On Drift Surfaces in Wright Valley, Axial Glaciations From The West Axial Glaciations From The East Wright Wright Wright Alpine Loop and Trilogy* Upper Upper Upper Glaciations Pecten Trilogy and Wright I, II III IV terminal Lower moraine Relative frequency Frequent Infrequent Infrequent Infrequent Rare Frequent Very of summer snowfalls (Blowing Frequent snow) Relative humidity High Medium Low to Low Low Medium High after snowfall medium Sublimation rate Slow Moderate Variable Rapid Rapid Moderate Slow Exposure to wind Exposed Variable: Exposed Variable: Exposed Variable: Variable: Undulating Ice tongue End moraine Undulating surface protects especially surface some exposed surfaces Relative cloud Frequent Frequent Less Less Less Less Very cover frequent frequent frequent frequent to frequent frequent Inferred soil Lower, Similar, Similar, See Fig, Similar, Similar Lower temperatures, due to but of can be can be compared to altitude shorter warmer warmer Meserve Glacier duration measurements * East of bedrock shoulder. 163 Group sedimentary rocks are abundant at the west end of the valley (Wright Upper Glaciations) but rare or absent elsewhere; volcanic rocks are abundant in deposits of some Alpine Glaciations and all deposits of Axial Glaciations from the east. Where marble is present in the parent material, calcium carbonate is mobilized and trans located to the undersides of pebbles. Calcium carbonate encrustations are rare or absent in Meserve Glacier soils because calcium-silicates are very resistant to weathering. Marble boulders have been brought into the valley by axial glaciations from the east, but marble is rare in the Asgard metasediments marginal to Meserve Glacier. (6.) Summary Samples from a chronological sequence of soils at Meserve Glacier are differentiated by chemical and mineralogical means and by surface weathering criteria. Physical and chemical weathering rates through out the valley vary significantly in response to differences in climate. Assuming the present climate at any point in the valley has remained constant with time, a relative chronological sequence of soils and hence glaciations is constructed. Numerical dates can be applied to the complete chronological sequence only if the physical and chemical weathering environment is similar at each site examined. Weathering environments in Wright Valley vary and a tentative correlation of glaciations is based on descriptions of soil profiles on representative till surfaces. APPENDIX A. Surface Weathering Criteria on Moraine Crests. East Side. Surface Weathering Criteria on Moraine Crests. West Side. B. Soil Profile Descriptions: Alpine I (WVMC 6); Alpine II (WV 5); Alpine III (WV 1). C. Particle-Size Analyses. D. Soil Temperature Readings. E. K-Ar Dating of Volcanics from Wright Valley by R. Fleck. 164 165 APPENDIX A, Surface Weathering Criteria on Moraine Crests. East Side. Meserve Glacier, Circular Area, Radius 10 m b ABC 1/r2 ALPINE I N.D. C none N.D. C N.D. C ALPINE II Principal Lateral Moraine (11 sites) 90.0 22.5 21.0 1.13 Recessional Lateral Moraines distal from crest (4 sites) 38,0 55.5 12,5 1.48 Looped End-Moraine (5 sites) 60.0 22.0 22.0 1.58 ALPINE Ila (5 sites) 41,5 20,0 21.5 2.08 ALPINE III (10 sites) 4,0 37.6 4.3 2.88 A: Number of boulders standing more than 10 cm above surface B: Number of boulders planed to the surface. C: Number of dike rocks more than 20 cm long. r^: Percent of resistant pebbles at surface. Percent of resistant pebbles at a depth of 50 cm. N.D.: Not Determined. 166 APPENDIX A. Surface Weathering Criteria on Moraine Crests, West Side, Meserve Glacier, ' a Circular Area. Radius 10 m A B C l/r2 ALPINE I c c (2 sites) N.D. none N.D. N.D. ATPTNP TT (4 sites) 83.0 34.0 34.5 1.45 d 1.60 6 ALPINE III d (5 sites) 35.5 40.5 33.3 2.02 1.18 6 0 A: Number of boulders standing more than 10 cm above surface. B: Number of boulders planed to the surface. C: Number of dike rocks more than 20 cm long. k r^: Percent of resistant pebbles at surface. r^: Percent of resistant pebbles at a depth of 50 cm. C N.D.: Not Determined. d Volcanic pebbles counted as non-resistant pebbles. Volcanic pebbles counted as resistant pebbles. 167 Appendix B. Soil Profile Descriptions. WV-1 December 28, 1968. Clear sky , strong wind from the east. Temperatures: °C. Time Ambient Air + 10.7 1400 Surface + 1 2.0 5 cm + 8 .0 10 cm + 6 .8 25 cm + 5.0 30 cm + 2.7 40 cm + 1 .8 40 cm + 5.2 1530 50 cm + 7.5 75 cm + 1 .0 100 cm - 1 .2 WV-5 January 8, 1969. Clear sky, wind from the east. Temperatures: °c. Time Ambient Air + 0 .8 1115 Surface + 6 .8 10 cm + 4.0 20 cm + 2.7 30 cm + 0.3 40 cm - 0 .6 50 cm - 1 .8 75 cm - 6 .2 • 84 cm - 6.5 1200 Contact with ice-cemented layer. WVMC-6 November 3, 1967. Clear sky, calm at this elevation. No temperatures were taken. APPENDIX B. Profile Description: ALPINE I (WVMC 6). ELEVATION: 950 m. SURFACE: BOULDERS: All competent, none cavernously weathered. SALT: None visible. DEPTH COLOR SALT COMPETENCY OF cm BOULDERS AND PEBBLES 0- 6( 8) 10YR6/3 (?) * None All Competent Partial Coating of Fines on Some Pebbles * Pale Brown 168 169 APPENDIX B. Soil Profile Descriptions WVMC-6 Alpine I moraine, east side of the Meserve Glacier. An ice- cored moraine near the crest of the glacier. Debris 10 to 20 cm thick overlying ice. The ridge is 1 to 1% m high. Elevation 950 m. See Figs. 9, 14, 32. 0-6(8) cm On crest. Significant winnowing of fines through boulder and cobble ridge. Some fines smeared on fine-grained granodiorite pebbles. Lower boundary abrupt, wavy. Pale brown, 10YR6/3(?). Loamy sand, dry, loose. One to three centimeters of material may be locally cemented to the ice-core. 170 Figure 32. Alpine I Profile (WVMC 6). Note how fine material has winnowed through boulders on surface. APPENDIX B, Profile Description: ALPINE II (WV 5). ELEVATION: 500 m. SURFACE: BOULDERS: Numerous upstanding; some cavemously weathered; some planed to surface, SALT: Slight accumulations beneath some dark pebbles. DEPTH COLOR SALT COMPETENCY OF cm FREE SALT ENCRUSTATION INDURATION BOULDERS AND PEBB] 0-2 10YR6/3 a ---- Slight ---- "Some Shattered 2-10 10YR5/3 b ---- Slight ---- Some Shattered 10-26 10YR5/3 b ---- Most Competent 26-50 10YR6/3 a ------All Competent 50-70 10YR6/3 3 ---- Slight ---- All Competent 70-80 10YR6/3 a Slight ------All Competent 80 + 10YR6/4 C ------—---- All Competent (Ice-cemented; color when frozen) Pale Brown Brown Light Yellowish Brown 171 172 APPENDIX B. Soil Profile Descriptions. WV-5 20 meters from survey point on Alpine II moraine, east side of the Meserve Glacier. Approximately 12 meters above WVM-4. Elevation 500 m. See Figs. 9, 16, 33, 34, 35, 36, 37. Surface: Numerous upstanding boulders, some cavernously weathered. An apparently inactive sand-wedge one meter upslope. SmaLl scoria pebbles on surface, very few dike rocks. Occasional boulder planed to the surface. Slight salt encrustation beneath pebbles. 0-2 cm Lower boundary abrupt, wavy. Pale brown, 10YR6/3. Loamy sand. Loose, dry, slight aggregation. Slight salt encrus tation beneath pebbles. 2-10 cm Lower boundary clear, wavy. Brown, 10YR5/3. Loamy sand, coarse fraction 25%. Dry, soft. Slight salt encrustation beneath occasional pebble. Occasional shattered boulder, most competent. 10-26 cm Lower boundary distinct, smooth. Brown, 10YR5/3. Loamy sand, coarse fraction 40%. Dry, loose. Slight free salt accumulation beneath pebbles. 26-50 cm Lower boundary gradual, wavy. Pale brown, 10YR6/3. Loamy sand, coarse fraction 30%. Dry, loose. Slight free salt accumulation beneath pebbles. 50-70 cm Lower boundary gradual, smooth. Pale brown, 10YR6/3. Loamy sand, coarse fraction 307.. Dry, loose. Slight salt encrus tations beneath pebbles, no free salts. 70-80 cm Lower boundary abrupt, wavy. Pale brown, 10YR6/3. Loamy sand, coarse fraction 20%. Dry, loose. Slight free salt beneath pebbles, no encrustations. 80+ cm Ice-cemented 173 Figure 33. Surface of Alpine IX Moraine, looking downslope from WV 5 pit site. Pit to right of P. Mayewski 174 Figure 34. Crest of Alpine II Moraine 50 m above WV 5 Pit Site. Note double crest separated by a channel which carried melt-water during recession of Meserve Glacier from the maximum Alpine II position. Upstanding boulders are numerous and many are cavemously weathered. Ice-axe for scale is 1 m long. Meserve Glacier in background. Figure 35. Upper portion of WV 5 Profile, Alpine II Moraine. Note that most boulders are competent. Shattered boulder at depth of 10 cm on far right. 176 Figure 36. Lower portion of WV 5 Profile, Alpine II Moraine. Note that all boulders are competent. Ice- cemented layer at bottom of profile is melting on exposure to sunlight. The ice-cemented layer is at a depth of 88 cm. Metric scale numbered in centimeters. i 177 Figure 37. Ice-cemented Layer, WV 5 Profile, Alpine II -Moraine. Pebbles and cobbles shown are frozen to the ice-cemented till. Ice-cemented material melting on exposure to sunlight. Metric scale numbered in centimeters. APPENDIX B. Profile Description: ALPINE III (WV I). ELEVATION: 470 m. SURFACE: BOULDERS: Most planed to surface; the few upstanding SALT: Moderate accumulations beneath dark pebbles DEPTH COLOR SALT COMPETENCY OF cm ENCRUSTATION INDURATION BOULDERS AND PEBBLES 0-4 10YR6/4 * Slight ---- Disintegration of Metasediments 4-14 10YR6/4 Moderate ---- Some Shattered 14-30 10YR6/4 Moderate Locally Strong Some Shattered 30-55 10YR6/4 Moderate ---- A Few Shattered 55-75 10YR6/4 Slight ---- All Competent 75-95 10YR6/4 Very Slight ---- All Competent 95 + 10YR6/4 Very Slight ---- All Competent * Light Yellowish Brown 179 APPENDIX B, Soil Profile Descriptions. WV-1 Alpine III moraine, east side of Meserve Glacier. Just west of a large upstanding weathered boulder. Approximately 40 m up- slope from WVM-2. Elevation 470 m. See Figs. 9, 15, 16, 20, 21, 31, 38, 39, 40, 41, 42, 43. Surface: Lag gravel surface. Significant number of boulders planed to the surface. Upstanding cavernously weathered boulders at this location, and continue on upslope surface. No volcanic fragments larger than 1 to 2 mm seen within two to three meters of the pit. Moderate salt accumulations beneath some dike rocks. 0-4 cm Lower boundary abrupt, wavy. Lighe yellowish brown, 10YR6/4. Sandy loam, dry, loose. Coarse fraction 60%. Slight salt accumulation beneath pebbles. Rotten meta sediments supply mica particles. 4-14 cm Lower boundary abrupt, wavy. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 407.. Moderate salt encrustations beneath pebbles. Some shattered pebbles, 14-30 cm Lower bondary abrupt, wavy. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 307.. Local strong salt induration* Moderate salt encrustations on sides of pebbles. Some shattered boulders. 30-55 cm Lower boundary clear, wavy. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 507.. Moderate salt encrustations beneath pebbles. Few shattered boulders. 55-75 cm Lower boundary clear, wavy. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 407.. Slight salt encrustations beneath some pebbles. No shattered boulders. 75-95 cm Lower boundary clear, wavy. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 307.. Occasional slight salt encrustations beneath pebbles and along sides. 95+ cm Lower boundary gradual. Light yellowish brown, 10YR6/4. Loamy sand, dry, loose. Coarse fraction 307.. Occasional slight salt encrustations beneath pebbles. 180 Figure 38. Surface of Alpine III Moraine, downslope from WV 1 soil pit. Note lack of upstanding boulders and compare with upslope view from same location (Fig. 15). The Onyx River is flowing along the valley bottom. 181 Figure 39. Upper Portion of WV 1 Profile, Alpine III Moraine. Note highly fractured boulders to depths of 40 cm and accumulation of free salts at a depth of 19 cm. 182 Figure 40. Upper Portion of WV 1 Profile, Alpine III Moraine, showing salt-indurated horizon. Salt-indurated horizon below nail (N) between 14 and 30 cm. Fractured boulders on left at depth of 45 cm. 183 Figure 41. Completely Shattered Metasediment Boulder in WV 1 Profile, Alpine III Moraine. Free salt crusts abundant between fragments. Metric scale numbered in centimeters. Figure 42. Free Salt-crystals at depth in WV 1 Profile, Alpine III Moraine. Metric scale numbered in centimeters. 185 Figure 43. Salt Encrustations beneath Pebbles in WV 1 Profile, Alpine III Moraine. Salt encrustation between 4,5 and 6 cm on scale; pebble between 6 and 7 cm on scale. 186 APPENDIX C« Particle-size Distribution; Weight Percent. Sieve and pipet analysis. Meserve Alpine I Alpine II Identification______Core WVMC-6 0-2h 2 ^ 5 5-10 10-20 20-30 > 4 mm 38.46 47.46 29.23 17.00 24.90 20.08 26.39 4 mm - 2 act 4.26 13.57 11.31 9.42 7.93 9.07 8 .8 8 Total 42.72 61.03 40.54 26.42 31.83 29.15 35.27 Salt-free weight percent Sand 2 .0 mm - 1 .0 mm 7.28 20.47 19.46 13.50 10.52 11.28 11.35 1.0 net - 0.5 am 6.14 15.36 16.04 13.81 12.18 13.68 13.53 0.5 mm - 0.25 mm 3.90 10.56 9.80 11.38 12.81 14.66 14.76 0.25 mm - 0.125 net 6.42 13.50 15.35 23.98 24.60 24.06 22.55 125 p - 105 p 1.84 2.34 2.96 4.50 3.88 3.56 3.08 105 p - 75 p 8.35 7.54 10.18 13.80 12.16 10.24 9.40 75 p - 50 p 8.53 5.25 5.69 5.78 5.80 5.02 5.12 Silt 50/1 - 20 p 19.01® 10.29 6.77 5.04 7.36 7.86 8.54 20 p - 5 / t 16.56 6.38 4.43 2.52 4.24 4.20 5.14 5/1 - 2 ji 8.17 2.83 2.65 1.38 1.78 3.23 2.18 Clay 2 /i • 0 .2 p I3.80b 5.18 6.32 4.02 4.43 1.92 4.10 *0.2 p N.D. 0.38 0.51 0.37 0.32 0.23 0 .2 2 Sand 42.46 74.94 ' 79.77 86.67 81.87 82.56 79.82 Silt 43.74 19.50 13.40 8.94 13.38 15.29 15.80 Clay 13.80 5.56 6.83 4.39 4.75 2.15 4.32 a Hydrometer analysis b Total N.D, = Not Determined 187 APPENDIX C. Particle-size Distribution (Continued). Alpine II Ice- Identification 30-40 40-50 50-60 60-70 70-80 Cemented > 4 mm 29.56 28.94 29.68 28.92 34.66 38.72 4 mn - 2 mm 7.77 8.70 9.68 8.05 7.54 7.89 Total 37.33 37.64 39.36 36.97 42.20 46.61 Salt-free weight percent Sand 2 .0 mm m 1 .0 mm 1 0 .8 6 11.16 12.08 10.78 10.30 1 2 .0 0 1 .0 mm - 0.5 mm 13.63 13.55 13.84 12.67 1 2 .2 1 13.74 0.5 mm - 0.25 mm 14.92 14.08 13.86 13.60 1 2 .1 0 13.30 0.25 mm 0.125 mm 21.97 22.72 21.90 22.31 19.90 2 1 .0 0 125 p - 105 3.27 3.56 3.52 3.48 3.68 3.06 105 }i - 75 p 9.58 10.27 10.46 9.98 11.15 9.96 75 M - 50 p 5.62 5.59 5.64 5.24 6.90 5,59 Silt 50 - 20 Li 8 .8 6 8.41 8.16 12.71 10.74 7.68 20 ji - 5 p 5.14 4.55 4.69 4.11 6.08 6 .2 0 m 2 M 2.17 2.31 1.84 1.60 2.18 2.26 I p m 0 .2 )i 3.81 3.47 3.74 3.19 4.30 4.28 1 0 .2 M 0.24 0.39 0.34 0.26 0.37 0.70 Sand 79.78 80.87 81.23 78.13 76.33 78.88 Silt 16.17 15.27 14.69 18.42 19.00 16.14 Clay 4,05 3.86 4.08 3.45 4.67 4.98 188 APPENDIX C. Particle-size Distribution (Continued) • Alpine III Identification 0-2>s 2^5-5 5-10 10-20 20-30 30-40 40-50 > 4 mi.' 41.22 41.13 26.18 36,50 25.37 24.30 23.88 4 mm - 2 mm 8.09 7.83 8.69 7.32 7.46 10.50 8.32 Total 49,31 48.96 34.87 43.82 32.83 43.80 32.20 Salt-free vei&ht percent Sand 2 .0 urn - 1 .0 ran 12.26 11.16 11.74 11.07 11.38 13.04 11.46 1 .0 mm - 0,5 ran 13.62 13.03 14.43 13.44 14.67 15.65 14.98 0.5 mm - 0.25 mm 13.90 13.32 15.78 14.40 16.40 16.87 16.38 0.25 mm - 0.125 ran 17.07 17.70 2 0 .6 8 18.66 20 .6 8 2 0 .2 0 2 1 .0 0 125 p - 105 p 2.60 2.62 3.06 2.92 3.04 2.87 2.94 105 p - 75 8.14 9.06 8 .8 6 8.87 8.82 8.16 8.59 75 p - 50 p 5.72 6.24 5.14 5.94 5.08 4.62 5.01 Silt 50 p - 20 11 10.50 10.46 7.72 10.80 8 .2 2 7.44 8.16 20 p - 5 M 7.22 6.96 5.34 6.74 5.54 5.48 4.04 5 p — 2 Ji 3.26 3.06 2.45 2.80 2.76 2.41 3.51 Clay 2 p 0 .2 )i 5.46 5.74 4.70 3.86 2.83 2.90 3.53 <1 0 .2 0.26 0.52 0.26 0.56 0.60 0.42 0.34 Sand 73.28 73.24 79.53 75.24 80.05 81.35 80.42 Silt 20.98 20.50 15.51 20.34 16.52 15.33 15.71 Clay 5.74 6.26 4,96 4.42 3.43 3.32 3.87 189 APPENDIX C. Particle-size Distribution (Continued). Alpine III Identification______50-60 60-70 70-60 80-90 90-100 > 4 ran 31.32 3A.62 2 0 .6 6 31.5A 27.32 A ran - 2 mm 7.92 8.6A 10.8 A 8.7A 9.08 Total 39. 2A A3.26 31.50 AO.28 36.A0 Salt-free weight percent Sand 2.0 ran - 1 .0 ran 11.5A 13.30 13.8A 12.A8 12.04 1.0 mra - 0.5 mm 13.8A 16.20 17.08 1A.1A 15.08 0.5 ran - 0.25 ran 1A.5A 17.52 18. 7A 14.16 15.85 0.25 mm - 0.125 ran 19.16 2 1 .A0 21. 9A 18.08 20.35 125 p - 105 p 2.81 2.82 2.72 2.5A 2.80 105 p - 75 p 8.60 7.86 7.16 7.93 8,27 75 ji - 50 p 5.A7 A.32 3.77 5.26 A.91 Silt 50 - 20 p 10.06 6.92 5.96 10.34 8. A0 20 p - 5>> 6.A8 A.A1 3.60 7.03 5.71 5 ji " 2 -U 2.60 1.82 1.73 3.46 2 .AO Clay 2 P - 0 .2 p A.A2 3.28 2.96 A.12 3.79 -1 0 .2 p 0.46 0.30 0 .A8 0.38 0.AA Sand 75.98 83.27 85.27 7A.67 79.26 Silt 19.1A 13.15 11.29 20.83 16.51 Clay A .8 8 3.58 3.AA A.50 A.23 APPENDIX D. Soil Temperature Readings. Alpine III Moraine Temperatures. Probes Buried Dec. 29» 1968, VJV-1 Temperatures in °C. Sunlight Conditions described as follows; 0; overcast; C: cloudy; S; sunny; shadow. Date 010269 010769 010869 Time 1530 1100 1700 1900 2000 2200 2300 0800 1000 1200 1400 1600 1800 2000 2200 Sunlight 0 S -C- S S S SS S s SSS SS S +1 meter - 1.0 + 3.2 + 1.6 + 1.0 - 0.2 - 2.2 - 3.2 - 3.2 - 0.2 - 0.8 + 1.0 - 0.5 - 1.1 - 3.0 - 5.0 +10 cm + 0.9 + 5.6 + 6.0 H ■ 3.0 + 1.3 - 1.2 - 3.0 - 2.0 + 2.9 + 3.0 + 2.3 + 1.9 + 0.9 - 1.2 - 4.0 Surface + 3.7 +11.2 +12.7 + 7.6 + 5.0 + 1.2 - 2.5 + 0.6 + 5.9 + 9.1 +10.2 +10.5 + 8,4 + 2.5 - 0.8 -10 cm + 3.2 + 0.6 + 3.4 + 4.0 + 4.0 4 3.0 + 0.9 - 1.8 - 0.2 + 1.5 + 3.0 + 3.9 + 3.8 + 3.4 + 2.8 -20 cm + 1.9 - 1.4 + 0.2 + 0.6 + 1.0 + 1.2 + 0.1 - 1.2 - 1.4 - 1.1 - 0.5 + 0.1 + 0,7 + 0.9 + 1.1 -30 cm + 0.5 - 1.8 - 1.3 - 1.2 - 1.1 - 0.9 - 1.7 - 1.0 - 1.9 - 1.3 - 1.5 - 1.8 - 1.1 - 1.2 - 0.6 _ -50 cm - 0.9 - 2.2 - 2.5 2.6 - 2.7 - 2.5 - 2.8 - 2 . 1 - 2.1 - 2.2 - 2.2 - 2.2 - 2.2 - 2.5 - 2.2 190 APPENDIX D. Soil Temperature Readings.. Alpine III moraine Temperatures. Probes Buried Nov. 18, 1969, WV-1 Temperatures in °C, Sunlight Conditions described as follows: 0: overcastj C: cloudy; S: sunny; shadow. Date 112369 112769 113069 Time 1415 1600 1800 2000 2200 1000 1200 1400 1600 1800 2000 2200 1200 1400 1600 1800 Sunlight S SSSS SS SS S S S S SS C +1 meter - 4.5 - 4.0 - 6.1 - 7.2 - 9.4 - 5.8 - 4.5 - 2.0 - 4.9 - 4.9 - 6.5 - 9.2 - 4.5 - 3.6 - 4.9 - 6.8 4- 10 cm - 2.0 - 3.0 - 4.2 - 6.5 - 9.0 - 2.8 - 0.8 + 1.8 - 2.5 - 0.5 - 5.2 - 8.4 - 0.1 - 0.6 - 3.0 - 6.1 Surface + 5.0 + 8.4 + 3.0 - 2.0 - 8.0 + 3.8 + 6.5 + 7.0 + 9.3 + 6.0 - 0.4 - 5.0 + 9.1 + 4.3 + 3.2 - 4.2 -10 cm - 3.9 - 2.0 - 2.0 - 3.3 - 4.9 - 6.0 - 4.0 - 2.0 - 0.8 - 1.9 - 2.2 - 3.5 - 3.1 - 2.7 - 1.8 - 2.1 -20 cm - 6.8 - 6.0 - 5.6 - 5.5 - 5.8 - 7.8 - 7.2 - 6.2 - 4.1 - 5.1 - 5.0 - 5.0 - 6.2 - 6.1 - 5.4 - 5.1 -30 cm - 8.0 - 7.8 - 7.2 - 7.2 - 7.1 - 8.0 - 7.8 - 7.5 - 6.9 - 7.0 - 6.9 - 6,6 - 6.9 - 7.4 - 7.0 - 6.8 -50 cm -10.0 -10.0 -10.0 -10.1 -10.2 - 9.5 - 9.5 - 9.2 - 8.3 - 9.5 - 9.8 - 9.6 - 8.6 - 9.4 - 9.0 - 9.1 191 192 APPENDIX D. Soil Temperature Readings. Alpine III Moraine Temperatures. Probes Buried Nov. 18, 1969. WV-1 cont. Temperatures in °C. Sunlight conditions described as follows: 0: overcast; C: cloudy; S: sunny; shadow. Date 011370 011470 Time 1000 1200 1400 1600 1800 2000 2200 2400 0400 0815 1000 1200 1400 1600 1800 Sunlight s S S C C 0 0 0 S S S S SC +1 meter - 4.2 - 1.5 - 1.2 - 0.8 - 1.9 - 3.8 - 4.4 - 5.1 - 6.2 - 3.1 - 1.4 - 0.5* - 0.9 - 1.6 - 2.8 +10 cm - 0.8 + 0.2 + 1.1 + 2.2 - 0.5 - 2.2 - 3.2 - 4.6 - 6.2 - 1.4 + 2.0 + 2.5 + 2.8 + 2.1 - 1.8 Surface + 6.1 + 8.9 + 9.2 +10.1 + 4.6 + 0.2 - 1.6 - 3.2 - 6.6 + 6.1 + 8.5 +10.6 +11.4 + 9.2 + 2.5 -10 cm + 0.2 + 1.0 + 2.1 + 3.2 + 2.9 + 2.2 + 1.2 + 0.2 - 1.2 - 1.6 - 0.2 + 1.4 + 2.6 + 3.5 + 3.2 -20 cm - 0.5 - 0.6 - 0.2 + 0.2 + 0.8 + 1.1 + 1.0 + 0.8 0.0 - 0.8 - 1.0 - 0.6 - 0.2 + 0.4 + 0.9 -30 cm - 0.8 - 0.5 - 0.6 - 0.2 - 0.2 0.0 + 0.2 + 0.2 0.0 - 0.5 - 0.8 - 0.8 - 0.8 - 0.8 - 0.2 -50 cm - 1.2 - 1.2 - 1.2 - 1.2 - 1.5 - 1.4 - 1.5 1.4 - 1.4 - 1.4 - 1.5 - 1.5 - 1.6 - 1.6 - 1.6 193 APPENDIX D. Soil Temperature Readings. Alpine III Moraine Temperatures. Probes Buried Nov. 18, 1969. WV-1 cont. Temperatures in °C. Sunlight conditions described as follows: 0: overcast; C: cloudy; S: sunny; 0: shadow. Date 011470 011570 011670 011770 011970 Time 2000 2200 2400 1000 2200 1000 1000 1200 1400 1600 1800 Sunlight S S SS 0 0 SS SS S +1 meter - 4.8 - 6.2 - 7.9 - 3.2 + 2.2 + 0.2 - 0.2 + 1.2 + 2.5 + 1.1 + 0.8 +10 cm - 3.0 - 5.6 - 7.9 - 0.8 + 3.0 + 1.5 + 2.2 + 4.2 + 4.5 + 4.8 + 2.8 Surface + 0.6 - 0.4 - 6.5 + 8.8 + 4.9 + 4.2 + 7.6 +16.1 +14.4 +12.8 +10.8 -10 cm + 2.0 + 0.9 - 0.4 - 1.8 + 4.9 + 2.6 + 1.1 + 3.0 + 4.8 + 5.8 + 5.2 -20 cm + 1.0 + 0.9 + 0.6 - 1.6 + 2.8 + 1.8 + 0.1 + 0.4 + 0.8 + 1.8 + 2.1 -30 cm - 0.1 + 0.1 + 0.1 - 1.1 + 0.8 + 1.0 + 0.1 + 0.1 + 0.1 + 0.2 + 0.6 -50 cm - 1.8 - 1.8 - 1.8 - 1.6 - 1.6 - 1.2 - 1.2 - 1.2 - 1.2 - 1.2 - 1.2 194 APPENDIX D. Soil Temperature Readings. Alpine II Moraine Temperatures. Probes Buried Nov. 18, 1969. WV-5 Temperatures in °C. Sunlight conditions described as follows: 0: overcast; C: cloudy; S: sunny; shadow. Date 112369 112769 113069 Time 1430 1615 1815 2015 2215 1015 1215 1415 1615 1815 2015 2215 1230 1415 1615 Sunlight S S S S $ SS S SSS sf S SS +1 meter - 5.0 - 6.0 - 6.0 - 7.1 - 9.9 - 5.8 - 5.0 - 1,8 - 4.5 - 5.1 - 7.5 - 9.0- - 3.2 - 4.3 - 5.3 +10 cm - 2.0 - 3.0 - 3.0 - 6.4 - 9.5 - 4.5 - 2.8 - 1.2 - 3.1 - 2,5 - 6.2 - 9.0 - 1.0 - 2.0 - 4.0 Surface + 7.0 + 7.8 + 5.7 - 2.2 - 7.9 + 6.0 + 6.6 + 8.0 + 9.2 + 6.2 - 1.1 - 6.2 + 8.2 + 5.9 + 3.1 -10 cm - 1.8 - 1.2 - 0.3 - 1.0 - 2.2 - 6.2 - 4.2 - 2.2 - 0.5 - 0.1 - 0.1 - 1.4 - 3.0 - 1.9 - 0.9 -20 cm - 5.8 - 5.3 - 4.5 - 4.2 - 4.2 - 7.3 - 7.0 - 6.2 - 4.9 - 4.4 - 4.0 - 3.8 - 5.9 - 5.5 - 4.9 -30 cm - 8.5 - S.5 - 8.2 - 8.3 - 8.2 - 8.5 - 8.5 - 8.5 - 8.0 - 8.5 - 8.2 - 8.2 - 7.9 - 8.0 - 8.0 -50 cm -10.3 -10.4 -10.3 -10.5 -10.6 -10.4 -10.2 -10.2 - 9.8 -10.2 -10.3 -10.2 - 9.6 - 9.9 - 9.8 -91 cm* -14.7 -14.0 -14.0 -14.1 -14.2 -13.8 -13.S -13.5 -13.1 -13.5 -13.5 -13.5 -13.1 -13.1 -13.1 * At the dry-permafrost - ice-cemented interface. 196 CM CM O 0 0 o a * m -O’ m • * * «• • • H i n m T l O C O CM o CM o CO CM + + + 1 I o 00 o CM 00 O ' < r o O' CO < r o C O CM o O' pH C/3 t o m • • • • • € 4 * o p H rv. M 0 C M o 4-1 u At the dry-permafrost - ice-cemented interface Alpine II Moraine Temperatures. Probes Buried Nov. 18, 1969. WV-5 cont. Temperatures in °C. Sunlight conditions described as follows: 0: overcast; C: cloudy; S: sunny; shadow. Date 011270 011370 011470 Time 2215 1015 i:-: 15 1415 1615 1815 2015 2215 2415 0415 0830 1015 1215 1415 1615 Sunlight $ S s SCC 0 0 0 t S S S S s +1 meter - 6.8 - 2.0 - 2.2 - 0.8 - 1.9 - 3.2 - 4.2 - 4.9 - 5.4 - 6.2 - 2.5 - 1.8 - 1.2 - 0.2 - 1.2 +10 cm - 6.2 - 0.4 - 0.2 + 2.1 - 0.1 - 1.1 - 3.2 - 4.6 - 4.9 - 6.2 - 1.2 + 0.4 + 0.8 + 1.1 + 1.1 Surface - 4.0 + 9.2 +10.2 +12.0 + 8.8 + 9.2 + 0.8 - 2.2 - 2.6 - 6.5 + 7.4 +10.5 +12.5 +12.8 +15.2 -10 cm + 2.9 - 0.5 + 1.2 + 2.8 + 3.9 + 4*2 + 4.0 + 2.5 + 1.5 - 0.6 - 1.9 - 0.8 + 1.0 + 2.8 + 4,2 -20 cm + 2.0 - 0.8 - 0.2 + 0.1 + 0.5 + 1.1 + 1.8 + 1.6 + 1.4 + 0.4 - 0.8 - 1.1 - 0.8 - 0.2 + 0.5 -30 cm - 0.9 - 1.2 - 1.2 - 1.5 - 1.8 - 1.8 - 1.5 - 1.5 - 1.2 - 1.2 - 1.5 - 1.6 - 1.8 - 1.9 - 1.8 -50 cm - 2.6 - 2.5 - 2.5. - 2.6 - 2.9 - 3.0 - 2.9 - 3.1 - 3.0 - 3.0 - 3.1 - 3.1 - 3.0 - 3.1 - 3.1 -91 cm* - 6.4 - 6.4 - 6.2 - 6.2 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 - 6.4 * At the dry-permafrost - ice-cemented interface. APPENDIX D. Soil Temperature Readings. Alpine II Moraine Temperatures. Probes Buried Nov. 18, 1969. WV-5 cont. Temperatures in °C. Sunlight Conditions described as follows: 0: overcast; C: cloudy; S; sunny; shadow. Date 011470 011570 011670 011770 011970 Time 1815 2015 2215 2415 1015 2215 1015 1015 1215 1415 1615 1815 Sunlight SS t S 0 0 SS S S S +1 meter - 3.9 - 4.5 - 6.8 - 7.9 - 2.1 + 2.0 + 0.6 - 0.8 - o. r + 3.4 + 1.8 - 0.8 +10 cm - 2.2 - 3.8 - 6.2 _ 8.0 - 1.1 + 2.4 + 1.2 + 0.8 + 1.8 + 5.5 + 3.4 + 0.9 Surface +10.4 + 2.8 - 2.5 - 6.6 + 8.8 + 4.8 + 5.8 + 7.0 +11.0 +20.1 +16.1 +11. 4 -10 cm + 4,6 + 4.0 + 3.0 + 1.1 - 2.2 + 5.9 + 2.6 + 0.5 + 2.1 + 4.2 + 6,0 + 6,6 -20 cm + 1.1 + 1.5 + 1.6 + 1.4 - 1.8 + 3.1 + 1.8 + 0.1 + 0.1 + 0.8 + 1.8 + 2.4 -30 cm - 1.9 - 1.9 - 1.6 - 1.5 - 1.9 - 1.2 - 0.8 - 1.1 - 1.1 - 1.2 - 1.2 - 1.2 -50 cm - 3.2 - 3.2 - 3.2 - 3.2 - 3.2 - 3.2 - 2.9 - 2.8 - 2.8 - 2.8 - 2.8 - 2.8 -91 cm* - 6.4 - 6.5 6.4 p. 6. 4 6.4 - 6.4 - 6.4 - 6.2 - 6.2 - 6.2 - 6.2 - 6.2 198 * At the dry-permafrost - ice-cemented interface. 199 APPENDIX E. K-Ar Dating of Volcanics from Wright Valley by R. Fleck. 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