174 THE ANTARCTIC. 



to a height of 490 to 590 feet— the eastern half of the 

 island is occupied by Mount Percy to which Ross assigns 

 a height in round numbers of 3,600 feet. This mountain 

 is like a fiat cupola in form, from which two steep rocky 

 cones rise, and these according to Ross were entirely free 

 from snow. A few officers thought they saw clouds of 

 smoke rising from the summits ; Ross, on the contrary, 

 was of opinion that this appearance was caused either by 

 clouds or by snow-drift. Meanwhile there is a probability 

 that careful investigation might prove Mount Percy to be 

 a volcano. The whole island is completely covered with 

 ice and snow. On the south side the inland ice descends 

 into Active Sound, forming deep clefts in coming from 

 the plateau of the island, and these, of course, parallel to 

 the coast line ; the mass of ice enters the sea as a rampart 

 upwards of fifty-nine in height. Farther to the east iso- 

 lated " nunatak" 1 above the ice have been observed from 

 the Sound, and Gibson Bay is equally girt in ; only one 

 rocky peninsula, Cape Alexander, about 200 feet high, is 

 free from ice. Here clear geological lines form a profile 

 that might have given some information concerning the 

 geological structure of the island, but unfortunately it has 

 been observed only from a distance, and even then not 

 by an expert. Charles Donald, the medical officer of 

 the Active relates that the rocks of which Cape 

 Alexander is composed in general appear black, hard 

 and crystalline. This mass is, however, traversed by two 

 distinct narrow layers of softer, slate-like rock, sloping 

 south at an angle of 45°, and recognisable by their light 

 brown colour. Immediately below them lie — and here 

 the data are somewhat vague— numerous flat, angular 

 stones, which are to be regarded as an accumulation of 

 debris, but for the rest correspond to the before-men- 



1 Originally a Greenland expression for rocks appearing in the 

 inland ice. 



