REPORT OF THE STATE PALEONTOLOGIST 1901 641 



an the gradually submerging Appalachian yalley trough into 

 .'New Jerse}'^ and probably across the Delaware into Pennsyl- 

 vania, where, according to Weller, it rests on Lower Trenton or 

 Black river limestone. If this succession is normal, then we 

 have a good indication of the age of the Chazy, and again of the 

 later strata containing the distinctively European fauna charac- 

 terized by Paterula, Christiania, Agnostus, Ampyx and Aeglina. 

 The latter must be older than the Black river and younger than 

 lower Stones river, the latter of which we consider about equiva- 

 lent in time to the Chazy and Levis. Following the same line of 

 reasoning, w^e see that the Chazy of the Champlain-Quebec val- 

 ley and the Ottawa basin was succeeded by an interval of eleva- 

 tion and probable erosion preceding the Black river invasion. 

 Again we conclude, the upper limit being fixed by evidence 

 touched on in a succeeding paragraph, that the Normans kill 

 shale is about Middle Trenton, as demonstrated by Kuedemann, 

 or a little later in age. 



While the Chazy and the greater part of the Stones 

 river deposits were being laid down elsewhere, nearly all of 

 the middle Appalachian area, together with Xew York and 

 much of Canada north of the St Lawrence, constituted a great 

 and continuous land area, and it was only with the advent 

 of the Black river and the underlying Lowville limestone, which 

 is equivalent to the extreme top of the Stones river, that the 

 Mississippian sea at last spread over a considerable part of this 

 territory. Judging from the uniform age of the basal member Black nver 



invasion 



of the Mohawkian in Xew York and Canada, it seems almost 

 certain that the Black river sea accomplished the submergence 

 of the troughs surrounding the Adirondacks and lying south of 

 the Laurentian nucleus, or Canadian shield of Suess, almost 

 simultaneously. It is therefore eminently proper to speak of this 

 «tage of the subsidence as the Black river invasion. ' 



The Trenton sea seems to have maintained very nearly the 

 «ame outline here as the Black river, and like that sea, at first, 

 and then again near the close of its age, transgressed the Quebec 



*Weller. Geol. sur. N. J. An. rep't, 1900. p. 5; and Kummel, p. 53. 



