136 WITH SCOTT: THE SILVER LINING 



the lake and the actual face of the glacier was an area of 

 distributed silts, which extended under the glacier ; while the 

 latter also contained bands of silt, which were boldly curved 

 in the form of an arch with the centre thirty feet above the 

 limbs. Here the glacier can be exerting no erosive action on 

 its bed, and I believe that for a long period thaw and freeze, 

 wind and water, have been the chief agents in eroding the 

 Taylor Valley hereabouts. 



Leaving the glacier and the upper lake, I proceeded east 

 to the Riegel. As I climbed up the slope of the hill, I was 

 delighted to find that it was composed of granite in situ. 

 This bar across a great glacial gorge was paralleled by many 

 in the Swiss Alps, and any light which can be thrown on 

 their occurrence in the path of an apparently irresistible power 

 like an immense glacier, will be of interest. 



In my opinion this bar (or riegel), and the more important 

 one we discovered some ten miles east, are relics of " steps " 

 in the original topography. A series of " armchair valleys " 

 (or cwms) were first cut out in the sloping margins of the 

 newly snow-covered land area. The plateau-ice in the interior 

 gradually grew in extent, and finally overflowed and drained 

 out through the largest cwm valleys to the sea. By degrees 

 it eroded many of the cwm features, but it left relics of their 

 presence in the form of these " bars " and basins. This is 

 what I call the "palimpsest" theory, and I shall explain it 

 more fully when I describe the elongated valleys of the 

 Koettlitz ice tributaries. 



I slid down the steep eastern face of the Riegel, where 

 King Frost had gnawed away the cliff and built up a steep 

 ramp of talus, and reached the channel connecting the two 

 parts of Lake Bonney. This was twenty feet deep and filled 

 with water, of which only the top six inches was frozen. 

 Large laminae of dull green algae covered the bottom of the 

 lake, and just at the snout of the glacier a bright red alga 

 lent an unusual touch of colour. 



Perched high up on the shoulder of the valley and close 

 to the Rhone glacier, Debenham made out a small black 

 crater, and I got a fairly good telephotograph of it from our 

 camp. It is probable that the basalt debris I found near the 

 lake had fallen from this crater, which was several hundred 

 feet wide. Its position on this glaciated shoulder is very 



