20 NEW YORK STATE MUSEUM 



inches of throw. The larger faults are from I to 3 feet apart. 

 The downthrow in each case is to the west.. The slates, in some 

 outcrops phyllitic, dip east at an angle of about 6o°, and strike 

 n. e. and s. w. 



The tectonic structure of the rocks in this vicinity is not 

 ascertainable from local observations. At the base of the hill 

 on the west of the public road there is a large nest of white 

 vein quartz in the slates which may or may not have been a 

 factor in resisting and localizing the effects of the thrust which 

 produced the faults. 



South of this locality in the road corners at Pumpkin Hollow, 

 a postglacial fault with a throw of .75 inch was observed in blue, 

 crumpled slates. 



Two and a half miles southeast of Taghkanic village along 

 the road to Chrysler pond, on the hillside south of the road and 

 near the eastern end of a swamp in the east-west depression 

 which exists there, one postglacial break of about an inch with 

 a downthrow on the west was found in a rather resistant rock 

 shot through with quartz veins. 



When one considers the smallness of the exposures which are 

 available for observations — most of the rock remaining covered 

 with drift or soil and many of the exposures being deeply 

 weathered — it must be admitted that the slate belt through 

 Copake and Taghkanic is extensively broken by small postglacial 

 faults. Owing to the eastward dip of the slates, exposures are 

 naturally more abundantly observed on the western than on the 

 eastern slopes of the hills throughout this region. The failure 

 to find these fractures on the eastern slopes, where indeed many 

 exposures also occur, is perhaps explained by the fact that the 

 little steps produced by the faults serve to catch and hold the 

 soil from slipping and thus to prevent exposures. 



The rocks of this belt are mapped as " Metamorphosed Hud- 

 son " on the geologic map of New York published in 1901. 



General remarks on Hudson river area 



In the season of 1904 a reconnaissance was made of the district 

 from Glens Falls southward on both sides of the Hudson river. 

 All the certain and measurable faults of this character so far 

 found have been described in the above account. It will be 

 observed that the phenomena are apparently restricted to the 

 east side of the river along the western base of the Taconic- 



