BEEKMANTOWN AND CHAZY FORMATIONS OF CHAMPLAIN BASIN 515 



During the Beekmantown age, these authors assert, the Mississip- 

 pian sea was connected with the Atlantic basin by means of the 

 St Lawrence channel, which was formed by the northern part of 

 the restricted Appalachian trough. During the Chazy age this north- 

 ern part of the Appalachian trough had, in their opinion, become 

 divided by means of the Quebec barrier into two subparallel basins, 

 the Chazy basin to the northwest of the barrier and the Levis chan- 

 nel to the east. The former passed through the greater part of the 

 present Champlain valley into the Ottawa basin, the latter formed a 

 narrow channel between the Quebec and Green mountain barriers 

 and extended as far as Newfoundland. 



The present writer has differed somewhat from this view in cor- 

 relating the greater part of the Levis graptolite shale with the Beek- 

 mantown formation. To avoid entering upon this difference of view 

 we will here distinguish but the four grand marine divisions, recog- 

 nized by Freeh and besides, the Mississippian sea, the Newfound- 

 land embayment and the Champlain basin. 



The study of the relations which exist between the cephalopod 

 faunas of the Champlain basin and the Mississippian sea is greatly em- 

 barrassed by the barrenness of the latter basin in well preserved 'fos- 

 sils of the Beekmantown and Chazy formations. The Beekmantown 

 age has furnished but few cephalopods in the Shakopee for- 

 mation described by Sardeson and the Chazy formation is in the 

 central Mississippi basin represented by the St Peter sandstone, in 

 which the fossils are so poorly preserved that altogether only two 

 cephalopods from this formation have been described by Sardeson 

 [1896] and by Clarke [1897]. We are here, therefore, largely re- 

 stricted 1 to an investigation of the relations of the Champlain basin 

 in Beekmantown and Chazy time to the Newfoundland embayment 

 and the Atlantic and Baltic basins, but can properly draw certain 

 indirect inferences from the Mesochamplainic faunas of the Missis- 

 sippian sea. 



A perusal of the table of distribution of a number of cephalopod 

 genera, that precedes this chapter [p. 513] leads plainly to the infer- 



l Mr E. P. Berkey [see " The Paleogeography of Mid-Ordovicic Time " in 

 Science, n. s. 1905, 21:989] has lately advanced the view that the St Peter 

 sandstone, as well as each of the most important sandstones below, represents 

 " an extensive retreat and readvanceof the sea." If this contention that the 

 St Peter sandstone represents largely material reworked by the sea and the 

 wind is true, then there is little hope of ever obtaining a satisfactory suite of 

 cephalopods from these beds, since the shell-bearing cephalopods have, as a 

 class, generally kept well out to sea. 



