218 New York State Museum 



involved in a period of mountain building which produced 

 the Appalachian mountains. This seaway on the north 

 was sometimes open to the Arctic region, also to the 

 North Atlantic through the New England and New- 

 foundland region at which time these waters with their 

 faunas also entered parts of the geosynclinal trough. In 

 New England and the maritime provinces of Canada 

 long, narrow strips of land alternated at times with nar- 

 row sounds. In the west was a land mass also important 

 but less well known, Cascadia. It occupied the western 

 border of North America and extended for an unknown 

 distance into the present Pacific ocean. The narrow sea- 

 way of the Cordilleran geosyncline separated it from the 

 main continent and at its greatest extent reached from 

 southeastern California to the Arctic ocean. In this geo- 

 syncline or area of more or less continuous depression 

 were laid down the principal western Paleozoic deposits 

 which toward the close of Paleozoic time were folded 

 into the Paleozoic Cordilleran Mountain chain. From 

 this Cordilleran seaway the waters of continental seas 

 spread eastward while the waters from the Appalachian 

 seaway spread westward. Sometimes the two geosyn- 

 clines were in communication by means of a transverse 

 geosynclinal trough extending through Arkansas and the 

 southern Gulf states. The Canadian Shield, that oldest 

 portion of the North American continent bordering Hud- 

 son bay, has already been mentioned under the discus- 

 sion of the Archeozoic and Proterozoic eras (p. 198) 

 and its peneplanation (Laurentian peneplane) at the close 

 of the Archeozoic pointed out. In Paleozoic times this 

 area constituted a central, low-lying land formed by the 

 surface of the old Laurentian peneplane and its later 

 modifications. Continental seas expanding from the geo- 



