ROCKS OF ATLANTIC TYPE 309 



In conclusion, it may be said that in its kersantites, sphene-bearing diorites, and 

 granophyric quartz-dolerites with rhombic pyroxenes, the rocks of the Ross Sea 

 region bear some resemblance to the Andean types, but the whole of the granites, 

 the granite porphyries, the quartz- and felspar-^jorphyries, as well as the old Tertiary 

 and Post-Tertiary alkaline lavas containing anorthoclase, leucite, nepheline, &c., the 

 typical kenyte, with associated trachytes, phonolites, sanidinite, leucitophyre, trachy- 

 dolerite, tephrite, &c., are distinctly alkaline, and not therefore Andean. Dr. Jensen 

 considers that the basalts without olivine, the olivine basalts, the limburgites, magma 

 basalts and magnetic basalts of Ross Island, are all to be regarded as extremes of 

 basic difterentiation of a magma of the composition of intermediate kenyte. Such 

 kenytes, constituting by far the greater proportion of the eruptive masses of Ross 

 Island and South Victoria Land, are distinctly of Atlantic type. 



We, therefore, quite agree with Dr. Philippi and Dr. Prior in regarding the type 

 of eruptive rock represented in the western mountains of the Pioss Sea region as 

 essentially Atlantic. 



In reference to the rocks so far recorded from King Edward VII. Land the case 

 appears difterent. A specimen of granite collected and presented by Lieutenant 

 Shiraze from this region is rich in biotite and plagioclase. Roald Amundsen records * 

 that Lieutenant Prestrud of his expedition obtained from this region at Scott 

 Nunatak specimens of white granite, micaceous granite, granodiorite, quartz- 

 diorite, diorite and quartz-diorite schists. The diorite rocks appear to resemble, 

 petrologically, the Pacific type. 



In discussing the general relations of Antarctic to other parts of the world, after 

 giving a short sketch of recent observations, we naturally turn to the master of 

 earth tectonics, Suess. 



In his chapter dealing with the oceanides and their relations to the south,! 

 Suess makes the following important statement in regard to South Victoria Land : — 



" These characters, notwithstanding the number of recent volcanoes, do not 

 indicate a Pacific structure. The horizontal position of the sandstones, the Avide 

 distribution of gneiss and granite, and all the contours show that this plateau 

 belongs to the Atlantic type. As regards South Victoria Land, we must agree that 

 the coast is broken off. It recalls the fractures of East Africa rather than a Pacific 

 arc, and this comparison is in complete accordance with the conclusions of Prior based 

 on the nature of the rocks. Whether or not King Edward VII. Laud, which is 

 situated farther east (lat. 7G^-78° S., long. 100''-150^ W.), and has furnished loose 

 fragments of ancient rocks, must be referred to the same type, can hardly be deter- 

 mined at present. It is certain that the regions lying still farther east, such as 

 Graham Land, possess a different structure." 



* The South Pole, vol. ii. p. 396. 



t "Face of the Earth" (Das Autlitz iler Erile), by Eduard Sue.ss, translated by Hertha B. C. Sollas 

 under the direction of W. J. Sollas, vol. iv. pp, 293-294. 



2 R 



