Handbook of Paleontology 355 



that the land of Appalachia probably never reached Al- 

 pine heights but was slowly raised as the Appalachian 

 trough sank. In the beginning of the Devonian (Helder- 

 bergian epoch) the seas were small and shifting. The epi- 

 continental waters were confined almost entirely to the 

 Appalachian trough and the Cordilleran area. The Appa- 

 lachian trough opened to the Atlantic on the northeast 

 (Gaspe region) and the fauna from that province entered 

 its waters. Erosion occurred over the interior of North 

 America. As Lower Devonian time continued the sea in 

 the Appalachian trough deepened and enlarged and a sub- 

 sidence in the south permitted the sea to spread over 

 western Tennessee into Missouri, southern Illinois and 

 Oklahoma. In the Gaspe area about 1500 feet of lime- 

 stones represent the Lower Devonian (Helderbergian and 

 Oriskanian series). The Helderbergian sea also covered 

 northern and southern New Brunswick, northern Nova 

 Scotia, northern Maine and part of its coasts and occu- 

 pied the New England troughs. In the west Helderberg- 

 ian formations have only been found in the Nevada 

 trough, and Helderbergian fossils are found in the north 

 on the shore of Kennedy channel (Lat. 80° N.). 



The sea withdrew from part of the Appalachian trough 

 at the end of the Helderbergian epoch and in the erosion 

 that followed much of the Helderberg deposits were re- 

 moved in some areas. The lime sediments from this ero- 

 sion, during the retreat of the sea in late Helderbergian, 

 locally accumulated in depressions and formed a detrital 

 lime rock (the Port Ewen beds). At this same time de- 

 position continued in the northern area of the trough 

 forming the thick Lower Devonian series at Gaspe. Dur- 

 ing the period of withdrawal of the sea the eroded land 

 surface was accumulating sand from various sources so 



