78 NEW YORK STATE MUSEUM 



where the highway crosses it by a ford in a northeasterly direction 

 and in the extreme northeast corner of the EHzabethtown quad- 

 rangle. This is illustrated in figure 13. The country rock is 

 anorthosite which has been cut bv an east arid west gabbro dike, 

 2"] feet wide. Still later but before the faulting a narrow black 

 trap dike penetrated both rocks with a northeast strike. The com- 

 plex was then dislocated by two faults of which the westerly one 

 moved the two dikes to the south about the width of the gabbro, 

 and the more easterly moved the eastern prolongation about 10 

 feet back to the north. The figure gives the actual exposures, and 

 where no rock symbol appears they are beneath the stream gravels. 

 The trap dike appeared to terminate against the western bank, but 

 no appreciable faulting was evident. 



Figure 14 illustrates all that can be seen of a horizontal band of 

 black hornblendic rock in the white Grenville marble, a hundred 

 yards north of Cheever dock. This is believed to be a dike or 

 narrow sheet, which, 6 feet in width, penetrated the limestone. It 

 has been so broken that only three blocks remain visible and two of 

 these are separated by 60 feet of an interval. The limestone has 

 molded itself into the interval, obviously while plastic under pres- 

 sure, illustrating those flowage phenomena which led Professor 

 Ebenezer Emmons to consider the limestone an igneous rock,^ 



O 10 ^_o'^^ 



Fig. 14 Fault2d blocks of black hcr.iblenie schist, presumably intrusive and now in Gren 

 ville limestone, just north of Cheever dock, Port Henry 



]\Iuch the same thing is shown in plate 11 from a photograph in 

 the lim.estone quarry south of the Pilfershire mines and just east 

 of Barton brook. A sheet similar to the last has been broken into 

 three pieces, of which the middle one has been pushed upward by 

 the viscous limestone. 



In the mines we find the best cases of fauking and the ones most 

 clearly shown. Fortunately while the Cheever mine was being 



1 Geology of the Second District. X. Y. State Nat. Hist. Sur. 1842. 

 p. Z7- 



