LAKES AT CAPE ROYDS 



157 



Surface temperatui-e on April 1 

 Water, 1 foot from bottoni 



th was 



Below the ice at this point there was 4 feet of water, the lake here being only 

 13 feet deep. The layer of ice from 2 feet down to 5 feet was quite fresh, but that 

 tested both from above and below these levels was slightly brackish. There is much 

 less alga in this lake than in Green Lake and Coast Lake, and both water and ice 

 are appreciably purer, although there is even here enough decaying organic matter 

 to render the smell of the mud at the bottom very disagreeable. 



Blue Lake. This lake is situated in the main glacial valley of the Cape Royds 

 Peninsula, being really part of the boundary between the peninsula and the main- 

 land of Ross Island. Its southern end is partially blocked by a knoll of kenyte 

 with large snow-drifts on either side of it, while on the southern side of this ridge 

 lie slopes of neve and drift snow, covered with a layer of frozen spray, which form 

 part of the ice foot of Backdoor Bay. 



On the eastern or Erebus side the lake is bounded along its length by the snow 

 slopes of the mountain, which are interrupted at intervals by terrace-like accumula- 

 tions of morainic matter. To the south-east these snow slopes are broken, and 

 bounded by several strongly marked hills of kenyte, to the largest of which the name 

 of Sentinel Peak was given. South of this peak is a dried-up lake, the bed of which 

 is covered with an accumulation of soil containing diatoms and algfe. The western 

 side of the lake is bordered by the kenyte of Cape Royds, knolls of massive rock 

 standing out between slopes covered more or less thickly with morainic debris, while 

 here and there snow-drifts repose in semicircular hollows between divergent ridges. 

 These drifts are sometimes of sufficient importance to be underlain by considerable 

 neve deposits. 



The lake is divided into two distinct portions of about equal size by two sharp 

 ridges of kenyte, which traverse it from east to west, and have a gap of only 10 to 



