HUDSON RIVER BEDS NEAR ALBANY 



555 



The whole system of shales from the Lorraine at Waterford 

 through the Utica, upper (?) and middle Trenton shales and Dice!- 

 lograptus shales to the Cambric slates and again to the meta- 

 morphic slates east of the Cambric zone, which have been found 

 to be of "Hudson river age", proves by its conformabillty (ita 

 uniform eastern dip) that it was one in system of dislocation and 

 one in system of mountain-making. Hence the writer feels safe 

 in assuming that the great overthrust fault between the Dicello- 

 graptus beds and Cambric beds is a fault cutting parallel to the 

 axial plane of an overfold, the western underturned wing of 

 which is exposed in the four zones described in this paper. 



The orogenic and physiographic stages through which this 

 region then passed would have been: 



1 A folding of Appalachian type, involving all terranes inclu- 

 sive of the Lorraine beds (fig. 2). 



Fig. 2 Overfolding of Appalachian type {see fig 1) in Hadson valley of Albany. a=Cambrio j 

 l)=Beekmantown limestone iCalciferous) ; c slower Trenton limestone; d= Normans kill shalej 

 e=middle and upper Trenton shale; f= Utica shale; g= Lorraine beds. 



2 The formation of a fault in the underturned wing parallel to 

 the axial plane (fig. 3). 





Fig 3 Fault in underturned wing of fold. 



