CONTINENTAL DISPLACEMENT — SCHUCHERT 251 



THE MAKING AND BREAKING OF PANGAEA 

 THE TIME ELEMENT 



The rifting of Pangaea and the floating away of Australasia, 

 Antarctica, and the Americas are said to have begun east of Africa 

 in Jurassic time and west of Euro-Africa in early Cretaceous time 

 (PL 1). These dates are based at best on insecure paleontological 

 evidence ; nevertheless let us accept the hypothesis to see what it leads 

 to along other lines of geological inquiry. We are to believe, under 

 this supposition, that this immense rifting and drifting of the con- 

 tinents went on during one of the earth's most marked times of 

 crustal quietness, the early and middle Cretaceous, when almost no 

 mountains were made in the w^hole w^orld — a time almost devoid of 

 volcanic activity, when the continents were about as peneplaned and 

 low as they ever have been, and when they were flooded b}^ the great- 

 est oceanic transgressions of all times. The drifting continued dur- 

 ing almost the whole of Cretaceous time, which, on the basis of 

 radium disintegration, means for 65,000,000 j^ears, before the con- 

 tinents showed any marked crustal unrest, or even marked volcanic 

 activity. Wegener's theory emphasizes accumulating or lagging 

 effects in the crust, but why a lagging of something like 50,000,000 

 years ? 



On the other hand, Pangaea must have endured unbroken all 

 through the Proterozoic, or if it did not exist as early as this, at 

 least it was present during all of Paleozoic time ; yet two of the earth's 

 greatest times of mountain-making came toward the close of the 

 Proterozoic and of the Paleozoic and each was accompanied by a 

 glacial climate. Why was Pangaea not broken up at these times of 

 marked crustal unrest, and why did it break up in one of the times 

 of greatest crustal stability? Of course, all of this is as determined 

 by orthodox geology. Wegener's hypothesis calls for floating con- 

 tinents in a viscous substratum, all whirled to the east, and he com- 

 pares the continental blocks to icebergs floating in water. Why, we 

 ask again, was Pangaea not broken up during the Pennsylvanian- 

 Permian ? Was it the making of the late Jurassic Mountains of wide 

 extent in North and South America that started the fracturing of 

 this combined land mass? If so, why did not the time of greater 

 mountain making during the Pennsylvanian and Permian also have 

 the same effect? On the other hand, it will not do to say that 

 Pangaea came into existence during the Devonian or Silurian, since 

 ortliodox geology tenches that the continents of to-day were, in their 

 main features, already present in late Proterozoic time. 



