BY H. I. JENSEN. 513 



block- mountains, up to 10,000 feet in altitude, alkaline rocks are 

 also plentiful. 



For the Australian alkaline area I have shown the possibility 

 of great faulting in the East Moreton district, the existence of 

 a senkungsfeld-area over the Narrabri plains, west of the 

 Nandewars, and of another subsidence-area between the Darling 

 Downs and Mount Flinders. More evidence of this nature may 

 come out when the geotectonic geology of Australia has been 

 more thoroughly investigated. 



Alkaline Rocks with regard to Atlantic and Pacific 

 Coast-Types. 



A comparison of fig. 5 with Neumayr's map showing the distri- 

 bution of the Atlantic and Pacific coast-types (fig. 6) shows us 

 that practically all the world's alkaline areas are situated closest 

 to coasts of the Atlantic type. 



As the Pacific coast-type expresses the forces of compression 

 and mountain-folding, whereas the Atlantic type indicates that 

 the sea is making inroads into a faulted coast-line, the inference 

 is evident. 



I am therefore prepared to accept Prior's suggestion to call 

 alkaline rocks eruptives of the Atlantic type, calcic ones Pacific, 

 on the understanding that these names have no geographic 

 significance, but mere imply the forces which were dominant in 

 producing the lavas, namely, in the one case folding and com- 

 pression, in the other trough-faulting and contraction. Yet, I 

 think less confusing and more suggestive names could be chosen, 

 for example, Kat-epeirean (concerned in the destruction of a con- 

 tinent) for those of the Atlantic type, and An-epeirean (concerned 

 in the up-building of a continent) for those of the Pacific type. 



Permanency of Ocean Basins. — It will be seen from the above 

 that some of my views are in express antagonism to the theory 

 of the permanency of ocean basins as propounded by Professor 

 Penck and Sir John Murray. 



Already Professor Suess has for a long time maintained that 

 an Atlantis must have existed up to at least Middle Tertiary 



