302 TECTONIC GEOLOGY 



with those of South America is due to the enormous bend in the Imes forming 

 the long loop eastwards, connecting up Tierra del Fuego with the Falkland Islands, 

 South Georgia, the Sandwich group, the South Orkneys, and thence with the 

 South Shetlands and Graham Land.* A deep, Drake Strait, of over 2000 fathoms, 

 as far as at present known, separates Cape Horn from the South Shetlands. Even 

 at the Ross region end of the great horst there is a difficulty in correlating the 

 trend lines with those ot Australia and New Zealand. Towards the south-east 

 of the southern island of New Zealand the trend lines swing sharply rovmd, after 

 having been near meridional, towards the S.S.E., so as to clear Campbell Island, 

 leaving it to their west. There can ])e no doubt that the profound fracture of the 

 Kerinadec Deep prolonged south-south-westerly from the Tongan grou^) is inter- 

 rupted in its south-south-westerly course near the north-east end of New Zealand, 

 and, as shown by the bathymetrical contours, swings aroiuid eastwards so as to 

 pass to the east of the Chatham Islands, but then trends once more at first 

 southerly, then S.S.W. in the direction of Ross Sea. Scott Island, on the 180th 

 meridian, is a volcanic island lying near where a prolongation of these trend lines 

 would reach the east and west trend lines, marking no doubt heavy faults, which 

 run through the Balleny Islands. A study of the map (Plate II.) of the Australasian, 

 Antarctic, and South American trend lines certainly suggests that the great horst 

 is connected with the New Zealand plateau rather than with the eastern coast of 

 Tasmania and Australia. If this view is correct, proof of such former connection 

 should be afforded by submarine ridges at intervals, and possibly by STibmerged 

 volcanic cones, in the neighbourhood of the 170th meridian of E. longitude. At 

 the same time, in the Ross region, the general trend of the horst is somewhat 

 interfered with by powerful cross faults trending east and west. In connection 

 with the northward prolongation of the great horst towards Tasmania, it is of coiu'se 

 possible that a parallel structure trends northerly from the deep indent in the 

 coast to the east of Dr. Mawson's winter quarters at Adelie Land. Tliis trend 

 would approximately follow the meridian of 150° E. It is hoped that further light 

 will be thrown on these two important questions, viz. the trends of the submarine 

 ridges, respectively between Tasmania and the Ross Sea region, and between New 

 Zealand and the Ross Sea, by the sounding expedition about to be undertaken by 

 the S.Y. Aurora. It will be of special interest for this expedition to examine the 

 area where the Royal Company Islands are considered to exist.f 

 We may now pass on to the jietrogTaphical evidence. 



* Suess is cautious in the matter of considering this a continuous loop. " Face of the Earth," SoUas, 

 vol. iv. p. 495. 



t Recently a very important submarine bank has been discovered by Captain J. K. Davis of 

 Dr. Mawson's Antarctic ship Aurora, 250 miles south of Tasmania. See the Geographical Journal, 

 May 191.3. 



