82 NEW YORK STATE MUSEUM 



The northward projecting spurs of the Highlands indicate a 

 tendency to fold with the younger series, but owing to their crystal- 

 line condition and high coefficient of elasticity the gneisses broke 

 and were thrust up into the younger rocks, in some places carry- 

 ing the latter with them, and in others overriding them. The West 

 Hook series was apparently first thrust up and then dropped back 

 and has thus been preserved. 



The arrangement in echelon of transverse faults along the north- 

 western margin of this limestone belt seems to show the influence 

 of the gneissic substratum on which it rests. 



The northward pitch of the younger rocks, which is observable 

 in places, may be as readily explained as the result of greater 

 vertical movement at the south as of original inclination. 



The Mount Honness spur is plainly faulted on the north and 

 shows numerous transverse gaps (see plate 2). 



The abnormal position of the Lower Cambric caused much con- 

 fusion in early years and led to its assignment to the Potsdam on 

 the basis of its apparent stratigraphic position. 



The occurrence of numerous faults in the quadrangle suggests 

 that the apparent absence of a Aliddle Cambric miglit thus be 

 explained. 



The evidence now in, although in great need of being supple- 

 mented, shows that the limestones of the Fishkill belt are, in part, 

 the eastward representatives of those of the Wappinger creek belt. 



THE "HUDSON RIVER" SLATE GROUP 



The term " LIudson River " is used in this paper for the slates 

 of the quadrangle because of the extensive section displayed in 

 these rocks along the Hudson river and because the name is both 

 widely known and locally followed by those who refer to the mem- 

 bers of the slate formation. It is used only as the equivalent of 

 other names employed in this paper and entirely without reference 

 to the value of the term " Hudson River Group." 



Distribution and general relations. Members of this formation 

 underlie the major part of the C|uadrangle. At the present time 

 there are no representatives of it within the Fishkill mountains or 

 the Fishkill limestone of this quadrangle. Northwest of these rock 

 masses the Hudson River rocks are the prevailing ones. The lime- 

 stones of the Wappinger creek belt 0e faulted in with the slates. 

 Northwest of this belt the slates entirely conceal the limestones. 

 North of the Fishkill limestone block are several small patches of 



