igo DISCOVERY REPORTS 



east until the deep had been crossed, and a section plotted from the data obtained is 

 shown in Fig. 4. It will be seen that the ocean bed to the west slopes gently upwards, 

 with some irregularities, from depths of 1880 or 1900 to about 1600 fathoms, and then 

 rises very sharply to a minimum at 1195 fathoms. In the position where the section 

 was taken the ridge on which the islands stand has two crests and its breadth is only 

 fifteen miles. On the eastern side of the ridge there is no abrupt declivity ; the bottom, 

 however, falls more steeply than in the west to a depth of over 2000 fathoms and then 

 plunges to the bottom of the deep, which has here a depth of over 4250 fathoms. Farther 

 to the east the bottom rises as abruptly as it fell, until the mean level of the southern 

 ocean is reached at under 3000 fathoms. Where cut by our section the deep has a width 

 of only some twenty miles. 



Origin. It is evident that the entire group owes its existence to volcanic disturbance. 

 The rocks, composed mainly of reddish tuff and black basaltic lava, are closely similar 

 throughout the group ; and in five of the islands there is still volcanic activity in the 

 form of steam clouds and sulphur fumes. That this chain of volcanoes is bordered by 

 one of the ocean deeps is significant, and it is a feature which is paralleled in several 

 other parts of the world. 



Volcanic activity. We found, as others have done before us, that it is not always an 

 easy matter to determine whether steam is or is not rising from a particular island. The 

 summit is usually wreathed in cloud or mist, which as it clears may assume deceptive 

 forms, and powdered snow carried by gusts of wind may bear an amazingly close re- 

 semblance to steam arising from a fissure. We think, however, after examining each 

 island closely, that the present state of volcanic activity in the group may be summarized 

 thus: 



I. Islands showing definite activity, emitting vapours and fumes. 



Zavodovski. Main crater, emitting dense clouds of steam and vapour, near top of 

 snow-clad summit. Plateau on southern and eastern sides not glaciated and largely 

 devoid of snow, with small craters and fissures, some of which also are active. Strong 

 sulphurous fumes detected. 



Candlemas. Southern part with its three snow peaks heavily and completely glaci- 

 ated. Northern part a plateau of lava from which arises a hill with large crater at top. 

 Another crater at base of this hill a little above sea-level. Plateau and hills entirely 

 devoid of snow. Both craters active, emitting strong sulphurous fumes. 



Bellingshausen. A large crater at summit and fissures on south side of cone, with 

 steam and vapour rising from both. Entire island without glacier, but with patches of 

 snow. 



Saunders. Greater part of island heavily glaciated, with snow-clad cone ending in 

 a crater from which clouds of steam arise. South-eastern end of island with little or no 

 snow and with two extinct craters. 



Visokoi. A heavily glaciated cone, with clouds of steam arising from near its summit 

 and from a fissure on the steep north-western slopes. 



