IN THE DEGRADATION OF THE LITHOSPHERE. 393 



groups of the Pacific such as the Solomon, New Caledonia, Kerma- 

 dec, New Zealand groups there will be found an arrangement of 

 island masses which have for many years suggested to geologists 

 definite plans of grovip arrangement. It is not needful to detail 

 these here as they are too well known to need review, having been 

 considered so often in connection with the origin of coral reefs ; a 

 recent bibliography has been published by P. Marshall.^- 



What seems to the present writer one of the most suggestive of 

 recent theories in regard to these island structures in general was 

 put forth by Alexander Agassiz in various studies published in the 

 Memoirs of the Museum of Comparative Zoology.*^ 



As is of course well known the main ideas concerning coral 

 islands in the Pacific have centered about the ideas of subsidence 

 and numerous suggestions have been ofifered to satisfy this re- 

 quirement. Aggasiz in i898'*'* in discussing the reefs about Aus- 

 tralia expressed the idea that too much emphasis had been laid 

 upon subsidence and wished to bring in the factor of marine plana- 

 tion with "terraces of erosion" upon which coral masses would by 

 natural extension grow together and form the Great Barrier Reef. 



In later writings (Memoirs, Vol. XXVIII.) Agassiz has again 

 cited marine erosion as developing the platforms upon which the 

 reefs of various sorts would develop. 



Given a water condition favorable to coral life there is no doubt 

 that coral life would start along the rocky structures of the north 

 Atlantic just as is now to be seen in the warmer seas. The prob- 

 lem here is not the coral life but rather the development of a plat- 

 form upon which the coral organisms may persist. There can be 

 httle doubt that coral reef developments of various sorts would 

 be found today along Madeira-Azores groups if the water condi- 

 tions were favorable. 



I would wish to suggest then that a profitable field for further 

 study of coral life in the field in the Pacific islands may be found 



*2 p. Marshall, " Oceania," " Handbuch der Regional Geologic," Vol. 7, pt. 

 2, Heidelberg, 191 1. Reference may also be made to Suess, Dana, A. Agassiz, 

 Murray and many others. 



*^ See particularly Mem. Mns. Comp. ZooL, volumes from 1898 to 1903. 



^* Bull. Mus. Comp. Zool., XXVIII., 1898; see also Agassiz, Mem. Mus. 

 Comp. Zool., XXVIII., 1903. 



