CONTINENTAL DISPLACEMENT SCHUCHERT 267 



that they agree better, though distantly, with those of the Mis- 

 sissippi valley than they do with those of Africa. As paleontologists, 

 we can explain these faunal similarities between Brazil, northwest- 

 ern Africa, and the Mississippi Valley far more easily by long dis- 

 tance migration routes along shelf seas bordering a land bridge 

 across the Atlantic, than by the close union of these lands. 



In western Africa there are, at least, dated Middle Ordovician 

 mudstones, with Climacograptus^ Diflograpius palmeus, and D. in- 

 sect if rons, probably a long Silurian sequence of mudstones from 

 which are recorded Monograftus pHodon^ M. lohifei^ns^ and Arthro- 

 phycus, followed by a long sequence of Lower, Middle, and Upper 

 Devonian sandstones with an abundance of identified fossils. Then 

 there is a long hiatus followed by lower (Dinantian) and upper Penn- 

 sylvanian (Moscovian) faunas, succeeded by Permian continental 

 deposits with tillites. The next overlap of Tethys was in Cretaceous 

 time, and it was a widespread one, followed by others of the 

 Cenozoic. 



The pre-Cambrian formations of western Africa have tectonic 

 lines — the Africanides — that in general trend northeast 45° to 75°, 

 but there are also north-south strikes. The next time of folding — a 

 striking one — came during the later Silurian. These are the Saha- 

 rides, and it is now seen that they have no direct connection w'ith the 

 Caledonides of northwestern Europe, as is usually assumed. The 

 trends of the Saharides are more or less like those of the Africanides, 

 but the two maps of Cliudeau give them in the south as trending 

 northeast and then turning and striking east-west and folded on the 

 southeast and south. Then followed, much farther north, the late 

 Pennsylvanian orogeny — the Hercynides — with the trend-lines strik- 

 ing in a totally different direction, namely, from northwest to south- 

 east. Finally, in the Eocene-Oligocene came the folding of the Atlas 

 Mountains — the Alpinides of extreme northwest Africa — with south- 

 west-northeast strikes. 



In Brazil there is no orogeny of Silurian or Devonian time at all, 

 some but not markedly strong folding in the Permian, and none at 

 all in Cenozoic time. There may, however, have been a time of 

 decided folding in the early Paleozoic, either at the close of the 

 Ordovician or earlier. 



These facts show that there are but few geological connections 

 between Brazil and western Africa, and there should be many if they 

 once were closely adjacent. Each area has its own independent 

 geologic development, unlike that of the other, indicating clearly 

 that Brazil and northwestern Africa, since at least the Silurian, have 

 been independent and far separated. In this connection, we must 

 recall what Suess said in his famous book. The Face of the Earth : " 



"E. Suess, The Pace of the Earth, vol. 1, 1904 (German ed., 1885), p. 537. 



