FRACTURES AND DISLOCATIONS. 



135 



fracture changes its direction, and makes its way to the valley of the Mohawk. It is only 

 two miles from the river at Coeymans ; hut when it has passed so far as to be directly 

 west of Albany, it is twelve miles distant. This point is near the route of the Cherryvalley 

 turnpike, where it commences its ascent over the north end of the Helderberg range, 

 which route is mostly over the Hudson-river series. From Albany to near the foot of the 

 mountain, tiiese rocks are steeply inclined to the east and southeast ; while on the route 

 over it, they have the common inclination to the soutiiwest of the upper New-York rocks, 

 which does not differ much from thirty to forty feet to the mile. 



This fracture sends a branch north, which passes east of Schenectady. At Saratoga, its 

 western limit, as already stated, is Saratoga-springs, where it bounds on the west the 

 valley of the springs, and where the calciferous is the lowest rock which is exposed, and 

 which remains nearly horizontal, while the trenton appears on a lower level, as if it had 

 been affected by a down-heave. See fig. 16, p. 131. 



Fig. IS. 



,^. 



In this line of fracture, it is interesting to observe the modifications or changes which 

 the strata have suffered at different points. I therefore give two additional illustrations : 

 the first (fig. 18) is taken from the rocks four miles east of Schenectady, upon the line of 

 the canal. It exhibits contortions which the strata have undergone by the force of lateral 

 pressure. It shows only segments of the curves, one of which rises and forms a high 

 arch in the mural procession, while the other projects down beneath the surface. The 

 other (fig. 19) is taken from tlie line of railroad, two and a half miles west of Catskill. It 

 is a massive inverted arch in the thick-bedded sandstone of the Hudson-river series. A 

 great variety of contorted strata may be observed in the course of a mile on this road, of a 

 highly interesting character. These, however, are sufficient to show the character of the 

 disturbances to which this belt of rocks has been subjected. 



Fig. to. 



