34 G Ni:\v voiiK sTATi: museum 



the case tlie course uf \\\v Sihoharie and its two branches, the 

 Cobleskill and Fox kill, iimst 1m' cxjilaincd in another manner. 

 The^' must then l»c i*eo:arded as l)clonjiin^- to that type of inse- 

 quential drainage wliirh eats its way backward from that vaHey, 

 in this case the Mohawk river valley, whicli takes the place of 

 the inner lowhind in front of the normal cuesta. As these streams 

 flow in the opposite direction to that of the principal stream of 

 the coastal plain, to which they are nevertheless tributary, they 

 have received the appropriate name of '* obsequent " streams. 



As has been shown by Chamberlin^ the divide between the 

 Mohawk and a westward flowing river (the Ontario) was at 

 Little Falls N. Y. From this point the Mohawk flowed eastward 

 as a revived subsequent stream between the old land on the north 

 and the sediments on the south. Commencing its new term of 

 life on a peneplain surface on which it formed the master stream 

 of that region, it incised its bed without much selection. More- 

 over as the region had suffered faulting it is not surprising to find 

 that the bed of the Mohawk does not continuously follow the out- 

 crop of the same formation. The Mohawk joined the Hudson 

 then as now, the latter stream at that time undoubtedly receiving 

 a plentiful supply of tributaries from the Adirondack i*egion, 

 which probabl}' stood several thousand feet higher then than now. 

 Tributaries from the region east of the Adirondacks, which 

 eventuall}^ carved the Champlain valley, were also received by 

 the Hudson, though some portions of this valley were probably 

 carved by streams flowing northward and becoming tributary to 

 the Tertiary St Lawrence, which at that time headed near the 

 Thousand Islands. 



We must assume that during the Cretacic peneplanation the 

 crystalline belt lying east of the present Helderbergs, which may 

 or may not have been covered by the sediments during Paleozoic 

 time, w^as planed down sufficiently to allow the Hudson to cut 

 across it as the shortest route to the sea in Tertiary time. This 



^Chamberlin, T. C. Preliminary Paper on the Terminal Moraine of the 

 Second fJl.-icial Kpodi. U. S. (Jool. Sur. 'M An. l{(>p't. p. 'M\2. 



