162 



Temper atiires, 



Sui-face 

 Depth— 1 foot 

 2 feet 



GLACIOLOGY 



. - 26-5° F. 



. -21-5°F. 



. - 16-0° F. 



(bottom) -12-5° F. 



B. 



27ins. C. 



Towards the close of the winter Brocklehurst sank a trench in the northern half 

 of Blue Lake. Few details are to hand about the section, but the chief differences 

 from the ice of the trench in the southern area seems to have been the extension of 

 the markedly prismatic ice to 3 feet 6 inches below the surface. The ice at this 

 spot was 20 feet thick, and imderneath it was 2 feet of water. 



On April 3rd a small combined trench and bore, put down a short distance to the 

 west of what was later the site of Brocklehurst's trench, 

 gave a thickness of 2 feet 9 inches of ice, and a depth of 

 7 feet to the lake, which there had a gravelly bottom, that 

 is, at that time there was a depth of 4 feet 3 inches of 

 water under the ice at this part of the lake. 



Thus between April 3rd and October 17th we have 

 almost certain evidence that in this portion of the lake 

 17 feet 3 inches of ice was formed, as Brocklehurst's shaft, 

 completed at the latter date, was sunk in ice throughout 

 its whole depth of 20 feet, whereas on April 3rd there was 

 probably a thickness there of only 2 feet 9 inches of ice. 



Coast Lake. Phenomena due to ablation were very 



marked at this lake, large quantities of algae projecting 



several inches above the surface, as the original surface of 



the ice which formerly enclosed them had been lowered 



by evaporation. A peculiar feature induced by the ablation 



was the production of a secondary rippled surface on the ice. 



This rippled surface was, during the early summer days, 



before the melting of the lake, much accentuated, the thaw acting along the bottoms 



of the ripples far faster than it did along the ridges. A similar phenomenon on a 



much larger scale was very commonly seen on the Ferrar Glacier. 



Trenches sunk in Coast Lake. These trenches brought to light another peculiar 

 feature about Coast Lake. As will be seen from the sections, the whole or most of 

 the lake bottom was covered with a thick deposit of a kind of algous peat, thickest 

 at the centre of the lake, and gradually decreasing as the outside was approached. 

 Detailed Section of Lee. 



^.18 inches of cloudy looking ice, with regular layers of bubbles at intervals of 

 an inch to half an inch. In most of the lower layers the bubbles tended 

 to become drawn out and thermometer shaped, a tendency that increased 

 with the depth. The layers were less well defined and more numerous in the 



Fig. 53 



