162 THE ANTARCTIC. 



Shetland Islands have tertiary coal formations, even 

 though Seymour Island has tertiary formations. More- 

 over, the statement itself is at best a doubtful one. For 

 the present it is sufficient to determine that the north- 

 west flank of the South Shetlands evidently consists of 

 crystalline slates, that the descent in the north to the 

 level of the sea is very gradual, that per contra the 

 greatest elevations are found on the south-east coast, 

 that numerous islets, rocks, and cliffs are scattered along 

 the north-west coasts — -perhaps the remaining indications 

 of more extensive land, submerged by the action of the 

 waves — that the south-east flank is entirely devoid of 

 these detached rocks, and that for this reason the depth 

 of the sea on this side probably increases much more 

 rapidly than on the other. If all this be taken into 

 account, and it is borne in mind that the southern flank 

 is accompanied by active volcanoes, the thought arises 

 that the South Shetlands consist of either a contorted 

 or non-contorted mountain chain, the northern portion of 

 which, subsiding to the W.N.W., has remained standing, 

 while the southern has sunk into a chasm on which the 

 volcanic islands we now see arose simultaneously. It 

 would be highly interesting if these conditions could be 

 carefully investigated — an undertaking that might be 

 successfully accomplished by occasionally wintering here, 

 even if there were no actual polar expedition set on foot. 

 The volcanic islands referred to play an important 

 part in the later geological history of this region ; 

 they are situated on the south side of the central group 

 of the South Shetland Isles, to which they form a parallel 

 range. The charts give three : Bridgeman Island, Middle 

 Island, and last, and by tar the most interesting of all, 

 Deception Island. 



The smallest of these volcanic islands, Bridgeman 

 Island, is also the farthest distant from the non- volcanic 

 members of the group. According to existing surveys 



