Talus slopes and mountain walls at Tempelfjorden, Spitsbergen: a geomorphological study of the denudation of slopes in an arctic locality
by Anders Rapp
Unknown Binding, 1960
CONTENTS
ILLUSTRATIONS ............................................... VI
PR EFA CE ............................................................ 1
CHAPTER 1. INTRODUCTION ........................................ 3
1.1 Purpose of the investigation ............................ 3
1.2 Talus slopes, their form and development. A short general
presentation ................... 4
1.3 M ethods ................................................ 7
1.31 M orphology .......................................... 7
1.32 Developm ent ......................................... 8
1.33 The map material used ............................... 9
CHAPTER 2. DESCRIPTION OF THE AREA INVESTIGATED AND A
SHORT DISCUSSION OF ITS FROST-WEATHERING CLI
M A TE ................................................. 11
2.1 The choice of locality .................................. 11
2.2 General description of landscape ........................ 11
2.3 Bedrock ........... ................................ 14
2.4 The climate and its fluctuations in post-glacial times ........ 16
2.41 Statement of the problem .... ....................... 16
2.42 Air temperature, precipitation, frost changes ............ 17
2.421 D iscussion ........................................ 20
2.422 Summary ......................................... 23
2.43 Deglaciation and post-glacial climate changes .......... 23
CHAPTER 3. MORPHOLOGY AND DEVELOPMENT ON SLOPES ALONG
SIDE VALLEY GLACIERS. An Illustration of Late Glacial
Denudation and Slope Formation .......................... 27
3.1 Denudation of a nunatak at the Tuna Glacier .............. 27
3.11 Description .......................................... 27
3.12 D iscussion ........................................... 29
3.13 Sum m ary ............................................ 32
3.2 Slopes alongside Kommissoerbreen ........................ 33
3.21 Description of the valley .............................. 33
3.22 The morphology of the valley sides .................... 34
3.221 Description of the inner and middle part of the valley .. 35
3.2211 East side ....................................... 35
3.2212 W est side ...................................... 35
3.222 Description of moraine terraces in the outer part of the
valley ............................................. 37
3.23 Present-day turnover of material ...................... 39
3.24 Sum mary ............................................ 40
CHAPTER 4. THE MORPHOLOGY OF THE MOUNTAIN WALLS AND
TALUS SLOPES AT BIONAHAMNA .................... 41
4.1 The forms of the mountain walls .......................... 41
4.11 Discussion of the genesis of the rock-fall funnels ........ 42
4.2 The morphology of the talus slopes ...................... 44
4.21 Form, size, material and profile ........................ 44
4.22 Surface forms ........................................ 47
4.23 Vegetation ........................................... 48
4.24 Snow, water supply, and frozen ground ................ 49
4.25 Morphological division and descriptive account of the cones at Bjonahamna ....................................... 50
4.251 Talus cones characterized by small slides ............ 51
4.252 Talus cones characterized by mudflows .............. 51
4.253 Talus cones eroded by avalanches .................. 52
4.26 Average inclination in talus and similar slopes at Bjonahamna 52
4.3 Terraces on the talus slopes .............................. 53
4.31 The terrace at talus cone T9 .......................... 54
4.32 Other terraces of a similar kind in the neighbourhood of
Bionaham na ......................................... 55
4.33 Discussion ....................................... 56
CHAPTER 5. MATERIAL TURNOVER- IN TALUS CONES AT B]ONA
HAMNA, 1882-1954 ..................................... 59
5.1 Field observations, 1954 ................................. 59
5.11 Supply of debris ..................................... 59
5.12 Shifting and removal ................................. 61
5.121 Small talus slides .................................. 61
5.122 Transport by avalanches ............................ 62
5.123 Transport by water ................................ 62
5.1231 The salt content of the stream water .............. 63
5.1232 Probable total yearly removal of material in solution 63
5.124 Transport by wind ................................ 65
5.125 Removal of material by glaciers ...................... 65
5.126 Removal of material by abrasion .................... 65
5.2 Comparative examination of photographs taken between 1882 and 1954 ............................................... 66
5.21 Picture material used and methods .................... 66
5.22 Picture comparisons .................................. 68
5.221-5.229 Talus cones TI-T9 ........................ 68
5.230 The talus slopes on both sides of the mouth of Bjonadalen 72
5.3 Summary and discussion of the material turnover between 1882
and 1954 ............................................... 73
5.31 Wall retreat and supply falls .......................... 74
5.311 Larger boulder falls ................................ 74
5.312 Smaller boulder falls and pebble falls ................ 75
5.32 Shifting ............................................. 76
5.33 Removal ............................................. 77
5.34 The question of a continuous or non-continuous growth of
the talus cones ...................................... 78
CHAPTER 6. THE AGE AND DEVELOPMENT OF THE ROCK-FALL
FUNNELS IN THE LIGHT OF VOLUME MEASUREMENTS 80
6.1 Previously presented views on the age of the rock-fall funnels 80
6.2 Calculation of the volume of rock-fall funnels and talus cones 81
6.21 M ethods ............................................. 81
6.22 Calculation of the volume of funnel and cone T9 ........ 82
6.23 Volume measurements on other cones .................. 85
6.24 D iscussion ........................................... 86
6.25 Sum m ary ............................................ 89
CHAPTER 7. CONCLUSIONS ......................................... 90
7.1 Conclusions as to the development of the wall relief ........ 90
7.2 Conclusions as to the development of the talus cones ........ 90
REFEREN CES ........................................................ 93
APPENDIX (Photographs) (Plates l-XIII and
XVI-XX)
APPENDIX (Illustrations). Three loose maps and four photographs (Plates XIV and XV) in a pocket in the back cover.
ILLUSTRATIONS
Text figures
1. The basic shapes of the talus formations ............................ 5
2. Sketch showing the principles of slope development .................... 7
3. M ap of Spitsbergen .............................................. 12
4. Map of the surroundings of Tempelfjorden ............................ 13
5. Stratigraphy of Templet at Bjonahamna ............................ 15
6. Air temperature and precipitation, Green Harbour .................... 18
7. Number of "frost change days", Green Harbour ...................... 18
8. The variation of air temperature at Bjonahamna ...................... 20
9. Mean temperatures at Isfjord Radio between 1912 and 1955 ............ 25
10. Sketch-map of the terraces at the front of Kommissaerbreen ............ 38
11. Sketch showing the principles of development to rock-fall chutes and funnel 43
12. Profiles and inclination diagrams of the talus cones T5 and T6 at Bjona ham na . .......................................................... 46
13. Sketch of a series of bump holes over cone T5 ........................ 48
14. Cumulative curves of particle-size distribution on talus cone T6 ........ 52
15. Slope profile and inclination diagram from terrace at cone T9 .......... 54
16. Distance diagram of high terraces in the talus slopes near Bjonahamna 57
Plates
I. Mount Templet at Bjonahamna.
11 (a). View from the talus slope at Bjonahamna.
II (b). The front of Tunabreen.
II (c). Western face of Langtunafjell.
Ill. The front of Tuna- and Von Postbreen.
IV (a) Kommissarbreen from Templet.
IV (b). Talus cones at Kommissaerbreen.
V (a). Sindballefjell at Kommissaerbreen.
V (b). Terraces in front of Kommissa-rbreen.
VI (a). The steep front of Kommissaerbreen.
VI (b). Typical U-shaped chute above cone SI.
VII (a). South-facing slope of Templet.
VII (b). Scarp and talus cones at Bjonahamna.
VIII (a). Rock-fall chutes and funnels, Sindballefjell.
VIII (b). Bottom of spirifer funnel above cone TI, Bjonahamna.
IX (a). Surface of talus cone, Bjonahamna.
IX (a). Photograph and stone orientation diagram.
IX (b). The base break of talus cone T6.
X. The Sassenfjord side of Templet from the air.
Xl. Templet at Bionahamna in the year 1882.
XII. Templet at Bjonahamna in the year 1896.
XIII. Templet at Bjonahamna in the year 1924.
XIV (a).* Talus cones TI-T3 in the year 1882.
XIV (b).* The same view as'(a) in the year 1954.
XV (a).* Talus cones T3-T5 in the year 1882.
XV (b).* The same view as (a) in the year 1954.
XVI (a). Talus cones T6-T8 in the year 1896.
XVI (b). Talus cones T4-T8 in the year 1924.
XVII (a). Talus cones T5-T7 in the year 1954.
XVII (b). Series of bump holes in front of cone T5.
XVIII (a). Talus cones and terrace T8-T9 in the year 1882.
XVIII (b). The same view as (a) in the year 1908.
XIX. The same view as XVIII (b) in the year 1954.
XX. Collation of the various mass-movements observed at
cones T1-T7.
Map I.* Templet at Bjonahamna.
Map II.* Sindballefjell at Bjonahamna.
Map III.* Kommissaerbreen.
* Plates XIV and XV and
Maps I-I1l are in a pocket in the back cover.
Preface
Before I pass on to the dry, matter-of-fact chapters which follow I may be permitted to begin with a declaration of love for Spitsbergen and more particularly for Tempelfjorden and Tempelfjellet. The four of us who formed the little expeditionary group from Uppsala University to Tempelfjorden in 1954 were doubtless all equally grateful for the experience of seeing this iridescent and beautiful landscape. It is a com bination of Polar sea and Arctic mountain into a unity of infinite, free expanses of sea, of mountain and of glacier. I do not believe there exists a fresher, freer and fairer range of natural scenery.
From a practical point of view there are both advantages and dis advantages in choosing remote areas for investigation. One of the dis advantages in this case has been that I have not had an opportunity of going back to Tempelfjorden later, in order to fill up the gaps which my material naturally has after so short a time in the field as a full four weeks.
There are perhaps two authors especially, who by their writings have stimulated me in my now completed labours. One is B. H6gbom by his fundamental study (1914) of frost weathering of rocks on Spitsbergen. The other is J. Bfidel, who in 1948 drew up the guiding lines of a climate morphological classification and descriptive account of the cold regions which has been fruitful for research. That I have afterwards in essential points come to conclusions other than those of the authors mentioned and of earlier investigators does not imply that the value of their contribution is diminished. They were pioneers who smoothed the way for continued research.
Professor Filip Hjulstr6m gave the initiative impulse to the Spits bergen expedition. It was through his support that it came into existence. His stimulating and experienced guidance has been of decisive importance for the arrangement and reporting of my material.
My comrades, Docent A. Holm and Fil. lic. T. Roos, Zoologiska insti tutionen, Uppsala, and Mr. H.-E. Dahl, Narvik, have the credit of an expedition successful in all respects and characterized by an extra ordinarily good comradeship.
Dr. A. Orvin and Mr. B. Luncke, director and engineer respectively of the Norwegian Polar Institute, Oslo, have supplied and allowed me to use maps and aerial photographs of fundamental importance for my thesis. Dr. Orvin has with great goodwill had the report printed and included in the Institute's series of "Skrifter"
Professors G. Hoppe and S. Ru~dberg, Docent A. Sundborg and other teachers and colleagues from Geografiska institutionen in Uppsala have given me many valuable points of view and suggestions.
Mrs. E. H. de Geer has kindly allowed me to use picture material from the G. de Geer collections.
I have had a great advantage in being able to call upon the services of the staff of Geografiska institutionen to set in order a part of the material in a state ready for printing. Mr. Tiit and Mr. Ludvigsen, the cartographers, skilfully executed the text figures and Mr. Eriksson, the photographer, excellent prints and enlargements of photographs, which has been of specially great importance for this thesis.
Fair copies of the Maps Nos. I-III were drawn by Mr. Evensen, of the Norwegian Polar Institute. The thesis was translated into English by Neil Tomkinson, B.A.
Financial contributions for the field work have been received from the following funds and institutions:
Andr6efonden (Swedish Geographical Society), Bjurzons, Liljevalchs, Sederholms fonder (Univ. of Uppsala), Svensk-Norska Samarbetsfonden,
Fdiltforskningsanslaget (Univ. of Uppsala), and Anslaget f6r ograduerade forskare (Univ. of Uppsala).
To my wife and to all private persons and institutions who have helped me with my work on this thesis I extend my warmest thanks.
Anders Rapp.
Geografiska institutionen,
University of Uppsala,
March, 1959.
CONCLUSIONS
The reasons for the empirical correlation of varnish chemistry with surface age have appar ently been misunderstood. No evidence for sig nificant preferential leaching of elements from varnish is available at the Cima volcanic field: instead, variations in CR between varnish layers and between varnish collected from lava flows of different age are related to variations in major element concentration. Because of the lack of 15 10 5 0 0 15 10 5 0 10 20 30 40 50 60 70 Si (wt %) 0 10 20 30 40 50 Mn (wt %) Figure 5. Plots of cation ratios (CR) vs. Si and Mn for surface analyses of varnish from clasts on Crater Flat, Nevada; alluvial surface ana lyzed by Harrington and Whitney (1987). In contrast to positive correlation of CR and Mn present in analyses of Cima cross sections (Fig. 3), where there is no addition of sub 'trate, inverse correlation here suggests that Inificant amounts of high-CR substrate were \.ecluded in analyses. evidence for leaching. referring to the calibrated dating curves as "cation-leaching curves" is in appropriate. and interpretation of microenvi ronmental variations in CRs in terms of local variations in leaching environments (Dorn. 1989) is questionable. In addition, because the concentrations of Ca, K. and Ti in accreting varnish are related to major element composi tions that vary nonuniformly with time. use of an "initial ratio" that is assumed to be constant over time is not substantiated.
Many uncertainties remain concerning CR dating of rock varnish and the nature of the empirical correlations of chemistry with age. In the absence of significant leaching, mechanisms that cause changes in calculated CRs associated with the increase in varnish thickness over time seem more reasonable. Available data suggest that the empirical correlations may in part de pend on the incorporation of varying amounts of substrate into varnish analyses, the percentage of added substrate decreasing with increasing var nish thickness and therefore with increasing age. If this hypothesis is correct. then previous sam pling of varnish from compositionally variable substrates has increased uncertainties in the age estimates. Further testing of alternative hypoth eses using varnish collected from other areas is required to verify the underlying cause of the empirical correlations of chemistry with age that are the basis for the CR dating method.
REFERENCES CITED
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Dornm R.L.. 1983, Cation-ratio dating: A new rock varnish age-determination technique: Quaternary Research. v. 20. p. 49-73.
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______ 1989. Cation-ratio dating of rock varnish: A geo graphic assesment: Progress in Physical Geog raphy, v. 13. p. 559-596.
Dorn, R.L. and Oberlander, T.M., 1981. Rock varnish origin, characterstics. and usage: Zeitschrift fir Geomorphologie, v. 25, p. 420-436.
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Krinslev. D.. and Anderson. S.. 1989. Desert varnish: A new look at chemicai and textural variations: Geological Society of America Abstracts with Programs. v. 21. no. 5. p. 103.
Perry, R.S. and Adams. J.B.. 1978, Desert varnish: Evidence of cyclic deposituon oi manganese: Na ture, v. 276. p. 489-491.
Pineda. C.A.. Peisach. M.. and Jacobson. L.. 1988. Ion beam analysis for the determination of cation ra tios as a means of dating southern African rock varnishes: Nuclear Instruments and Methods in Physics Research. v. B35. p. 463-466.
Quinlivan. W.D., and Byers. F.M.. Jr., 1977, Chemi cal data and variation diagrans of igneous rocks from the Timber Mountain-Oasis Valley caldera complex, southern Nevada: U.S. Geological Sur vey Open-File Report 77-724, 9 p.
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Reneau. S.L., Hagan. R.C.. Harrington, C.D., and Raymond. R.. Jr.. 1991, Scanning electron mi croscopic analysis of rock varnish chemistry for cation-ratio dating: An examination of electron beam penetration depths: Scanning Microscopy, v. 5. p. 47-54.
Turrin. B.D, Dohrenwend. J.C.. Drake. R.E.. and Curtis. G.H., 1985. K-Ar ages from the Cima volcanic field, eastern Mojave Desert, California: lsochron/West. no. 44. p. 9 - 16 .
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