ILLUSTRATIONS 



213 



PiGURE 1. — Gcosynclines (dotted), Lands (white), and Oceans or Mediterra- 

 neans (ruled) during late Proterozoic Time 



Black marks the known outcrops of Animikian, Keweenawan, Beltian. etcetera. 

 The Cordilleran trough may have opened into the Arctic Ocean. 



