280 SUPERFICIAL DEPOSITS 



to a few inches near the margin. A descending section of the peat deposit where 

 thickest was as follows : — 



(a) 18 inches (45 centimetres), cloudy ice with regular layers of bubbles at 

 intervals varying from 1^ inches to J inch in thickness. In most of the lower 

 layers the bubbles tended to become drawn out and to be thermometer-shaped, 

 a tendency that increased with the depth. The layers were less well defined and 

 more numerous in the lower few inches. 



(b) From 18 inches to 24 inches (45 to 60 centimetres), ice of similar type, but 

 yellow, and malodorous owing to gases produced by partial decomposition of the 

 plant tissues. 



(c) A layer 9 inches (22-5 centimetres) thick of the algous peat, which proved 

 on melting to be composed of small flakes of the algae. 



(d) A thin layer of ice fairly free from algfe and containing a series of small snow 

 tabloids and partially filled gas bubbles. 



(e) A thickness of 1 foot 3 inches (37-5 centimetres) of regularly stratified layers 

 of peat separated by very thin seams of fairly clean ice, and ending in a layer 4 

 inches (10 centimetres) thick of dense peat containing rather more gritty rock 

 jjarticles than the upper layers. 



It will be seen that the whole thickness of this deposit, including a good deal of 

 interlaminated ice, is about 4 feet. It will be noticed that immediately above the 

 top of the peat bed the ice is rendered conspicuously fibrous owing to very numerous 

 vertical bubble holes like the capillary tubes of thermometers. These seem to have 

 been formed by bubbles of escaping gas. 



One of the most curious facts about the occurrence of this peat is its regularly 

 stratified appearance, rendered most conspicuous by the laminae of almost pure ice 

 which support the beds. The reason for the intercalation of these ice laminfe is 

 hard to ascertain, for we have every reason to believe that the ice at Coast Lake 

 was thawed right to the bottom during both of the summers which we spent at 

 Cape Royds. 



The following is an analysis of the peat by Mr. F. B. Guthrie, F.C.S., Analyst 

 to the Department of Agriculture, New South Wales : — 



Sample of Algal Peat, Coast Lake, Cape Royds. 



100 



* Containing nitrogen, 0-39. 

 The ash is red in culour, and contains a considerable proportion of ferric oxide. 



