64 MB. F. DEBEXHAM OX A NEW [vol. lxXV, 



with debris. The actual moraines appear as lines of mounds 

 and ridges of ice thickly covered with gravel ; but in between 

 these lines the ice is full of silt and mud, some of it undoubtedly 

 wind-blown and some of it probably sea-bottom. The effect of 

 this debris is to increase the thaw in the summer to an enormous 

 extent, so that the whole of the sheet is seamed and dissected with 

 thaw-streams and pools. The general appearance of the surface 

 is one of picturesque grandeur, most gratifying to the artist but 

 heart-breaking to the sledger. The physical result of this heavy 

 thaw is of the greatest importance, for it reverses the order of 

 things as found on the Barrier, where there is an annual increase 

 by snowfall, and produces a net decrease or wastage from the 

 surface. It would be useful to present figures to support this 

 significant fact, but the difficulties of measuring thaw (except in 

 very general terms) are obvious, and the only alternative is to 

 quote instances to show its magnitude. 



The sledge parties of the Discovery Expedition, in travelling 

 between Black and Brown Islands, described the surface in the 

 following terms : — 



' Seen from a distance it appeared like a tumultuous sea with high crested 



waves curling towards us Long distances had to be done by porterage, 



■and in the thaw season we had sometimes to take off shoes and stockings to 

 cross rapid streams of water 2 and 3 feet deep/ 



It must be mentioned, too, that they were never there at the 

 height of the summer, late in January. 



Our own experience was no less striking, although we did not see 

 it during the thaw season. On the Lower Koettlitz Glacier we 

 sledged over many miles of ice which consisted entirely of frozen 

 thaw-streams with islands of higher ice in between. Many of 

 these had been 15 feet wide and 2 or 3 feet deep when running. 

 On the north side of the glacier a strong stream was still running 

 under a thin covering of ice, even in the beginning of March, and 

 we traced its course to the sea for a distance of over 20 miles. At 

 the mouth we estimated its rate at 3 knots, and its average cross- 

 section at 8 square feet. In the real thaw season this stream must 

 be worthy of the name of river, and in many places its original bed 

 •exceeded 30 feet in width. 



A very approximate measure of the rate of wastage may perhaps 

 be gathered from our experience at the northern edge of the same 

 glacier. While marching over apparently level ice there we con- 

 tinually fell through the thin coverings of former streams, the 

 water of which had run away since the superficial freezing, leaving 

 a space of some depth between the original surface and the floor of 

 the stream. The average depth of these ' sledge-traps ' over a large 

 area was about 20 inches, and it seems legitimate to regard that as 

 a rough measure of the wastage of a single summer. The propor- 

 tional area of these ' ghost streams ' to the solid ice was about 

 20 per cent., which would give a total annual wastage of 5 or 6 

 inches over the whole of this area. Moreover, at this part of the 



