64 WaUher — Origin and Peopling of the Deep Sea. 



manifested in mountain-building, and have to examine as well 

 whether in the earth's history there is discernible an increased 

 folding of the crust at the end of the Paleozoic. 



Everyone who is at all familiar with the events of that 

 epoch knows that at no other period did there arise anything 

 equalling the extent and grandeur of the mountain ranges of 

 the time between the Carboniferous and Triassic periods. A 

 gigantic range of mountain folds can be traced from Ireland 

 through all of France to the banks of the Rhone; a second 

 range extended from the Rhine northeast through Germany 

 to the Carpathians. The eastern Alps were mountain land 

 and in Switzerland as well are to be seen undoubted traces of 

 a former mountain range. In the same epoch arose the Urals 

 and simultaneously the Appalachians were thrust together in 

 North America. In the Sudan there probably arose a moun- 

 tain fold with great granite stocks at the termination of the 

 Paleozoic and in South America the Permian age of extensive 

 mountain folding was definitely established ! Even in eastern 

 Asia keen scientific explorers have been able to trace a Per- 

 mian period of folding from China to Japan and through the 

 interior of India to Sumatra. 



But where are to be sought the complementary movements 

 of this same time directed toward the center of the earth ? 



An answer to these questions is not difficult to find. For if 

 the present deep sea fauna contains predominantly Mesbzoic 

 types and in accordance with its whole character must be con- 

 sidered as a migration from the shallow sea ; if therein almost 

 all Paleozoic elements are lacking although such are repre- 

 sented rather numerously in the present shallow sea ; then the 

 deep sea must have originated at the end of Paleozoic time. 



And if in the same period of time we find that mighty 

 mountains have arisen almost everywhere on the earth, then it 

 is easy to bring the depressions of the deep sea basins into 

 direct connection with these folding processes. 



General biological grounds, the stratigraphic position of the 

 present deep sea fauna as well as tectonic investigations, force 

 us to the conclusion that the deep sea as a life-region is not a 

 characteristic of the earth in its oldest periods, and that its 

 origin falls in the time when in all parts of the present conti- 

 nents began tectonic folding movements which so decidedly 

 changed the relief of the earth's surface. 



