308 Naturalist at Large 



uncertainty among geologists than the matter of isostatic 

 balance. Only one thing is sure, isostasy must meet and 

 conform to known or presumably known facts, and the 

 fact that fundamental changes have taken place in the 

 form of the earth's surface in recent geologic time is not 

 to be denied. Such features as the Great Rift Valley of 

 Africa and its continuation, the Red Sea and the Dead Sea, 

 the Black Sea, the Basin of the Mediterranean, are held now 

 by geologists to be the results of nothing but gigantic and 

 fairly recent down-thrown fault-blocks. For other examples 

 of changes of land and sea level with relation to each other, 

 the Valley of the Po and the Central Valley of CaHfornia 

 are good evidence. The argument of isostatic balance may 

 probably be held to control the conditions in the Pacific 

 Basin as a whole, but isostasy cannot be used effectively as 

 an argument in a relatively small area anywhere. Professor 

 R. A. Daly tells me that there is clear evidence of the 

 fragmentation of a great land mass, including the Fiji 

 Islands and New Caledonia, but that there is no evidence 

 known at present of such a condition outside of a line 

 joining Yap, in the Caroline Islands, with the Fijis, 

 Kermadecs, and New Zealand. In addition, radiolarian ooze, 

 supposedly only to be derived from the deep sea, has long 

 been known from Barbados, Trinidad, Aruba, Buen Ayre, 

 and Curacaos, but the origin of this series of deposits has 

 been somewhat in dispute. Two recent papers by Dr. G. A. 

 F. Molengraff, however, describe deposits of which there 

 can hardly be any question whatever; one is "On Oceanic 

 Deep Sea Deposits in Central Borneo," ^ while the other is 



^ Kon. Ak. Wet. Amsterdam, Reprint from proceedings of 

 meeting June 26, 1909: 141- 147. (Reprint: 1-7.) 



