162 C. SCHUCHERT THE XORTH AMERICAX GEOSYXCLIXES 



The Lower Devonian sandstones are also widespread and extend frcni 

 Georgia to Xew York. Their thicknesses, however, never exceed hmi- 

 -dreds of feet, and accordingly Appalachia is not thought to have been 

 reelevated much at this time. 



In keeping with the orogeny of middle and late Devonian times 

 throughout Acadia, we see in the very extensive and thick Devonian delta 

 deposits of the Appalachian trough that northern Appalachia was then 

 also a highland and not very unlike the Sierra Xevada of today. 



Toward the close of the Mississippian. Appalachia was again reelevated, 

 and the proof of it lies in the 10,000 feet of coarse deposits of the coal 

 fields of Alabama, the widely distributed and thick Pottsville conglom- 

 erate and sandstones, and the general sandy nature of the thick deposits 

 of Pennsylvanian time. 



On the other hand, we may conclude from the very thick accumula- 

 tions of Paleozoic sediments in Pennsylvania, ranging between 30,000 

 and 1:0,000 feet in thickness, that Appalachia was several times a high- 

 land during Paleozoic time. This generalized statement is further sup- 

 ported by the folding of the western side of northern Appalachia and 

 presumably also of Acadia in Ordovician time, and by the very marked 

 folding of Acadia in the late Devonian; further, the presence in the 

 Appalachian geosyncline of thick sandstones of Lower Deyonian and 

 early Pennsylvanian ages shows that there was reelevation of the border- 

 land at the close of Silurian and Mississippian time. Therefore, directly 

 or indirectly, the evidence indicates that Appalachia was reelevated about 

 six times during the Paleozoic, namely, (1 ) at the very beginning of the 

 Cambrian, (2) late in the Ordovician, (3) somewhat during the Lower 

 Devonian, (1) in the Tapper Devonian, and (5) at the close of the Mis- 

 sissippian. Finally, (6) in the Permian came the greatest of all the 

 ■crustal movements, when the borderland and the geosyncline were folded 

 into an anticlinorium and synclinorium that together make the Appa- 

 lachian Mountains, of which today we see only the roots beneath the 

 ■dissected Cenozoic peneplain. 



ACADIA AXD XOVASCOTICA 



The northeastern half of greater Appalachia, properly greater Acadia, 

 Includes the Acadian geosyncline, the Xew Bruns^dck geanticline, and 

 the borderland Xovascotica. The latter is the homologue of restricted 

 Appalachia, and all that is left of it as dry land is a narrow strip of its 

 inner side making up the greater part of present Xova Scotia and Cape 

 Breton. The banks outside of these provinces and of Xewfoundland are 



