File:British Antarctic expedition, 1907-9, under the command of E.H. Shackleton - reports on the scientific investigations; geology (1914) (14767811665).jpg

Identifier: britishantarctic11914shac (find matches)
Title: British Antarctic expedition, 1907-9, under the command of E.H. Shackleton : reports on the scientific investigations ; geology
Year: 1914 (1910s)
Authors: Shackleton, Ernest Henry, Sir, 1874-1922
Subjects: Scientific expeditions Natural history Geology Paleontology Petrology Ice
Publisher: London : Published for the expedition by W. Heinemann
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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ul etching effect was observed on the Larsen Glacierportion of the Drygalski-Reeves Piedmont on January 31 and February 1,1909. Thesurface of the piedmont was found to be covered with curved anastomosing platesof thin ice, dipping at angles of approximately 30° or so, and on the whole, whilethe direction of dip varied, showing a general tendency to dip away from the northtowards the south. Sledging over these inclined thin sheets of ice might be compared to trampingover a wilderness of cucumber frames inclined at the above angle, the ice platessometimes supporting ones weight, sometimes giving way with a crash, and lettingone through up to ones thighs on to the surface of the solid ice below. Ourcolleague Murrays explanation of a somewhat similar structure probably applies tothis region also : *— In the height of summer the combined action of the sun and air on compacted • Heart of the Antarctic, vol. ii. p. 341. THAW EFFECTS 205 ^p^^:^- #itK Glacier iceForming largerounded domes
Text Appearing After Image:
Fig. 59. Sketch plan showing small inlet receiving the drainage of a surface glacial stream on thesouthern side of the Drygalski Ice Barrier Tongue at a point 20 miles west of its seaward end snow-drifts caused deep erosion of the snow. A kind of stratification resulted, which appeared to have no relation to any original stratification of the snow. Thin flat layers of ice were formed, separated by cavities. These dipped at a gentle angle 2 D 206 GENERAL GEOLOGY to the south, that is to say, their edges were directed towards the sun at the timeof day when it is highest. These ice plates were so fragile that they collapsed inmultitudes as we walked over the drifts, and a slight breeze whirled quantitiesof them along, often rolling them on their edges. In the Drygalski-Reeves Piedmont area these plates were much thicker,frequently quite strong enough to support the weight of a man. There can be little doubt that this remarkable and beautiful structure is theresult of etching of old snow-

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