58 NEW YORK STATE MUSEUM 



New Hackensack road ; then across this and for a short distance 

 to the south. The margin is then apparently broken by a spur in 

 a manner similar to that just described, although this time the break 

 appears to be along an extensive fault line. The slates which out- 

 crop south of the Poughkeepsie-New Hackensack road and west of 

 the cross road that leads from it to the Spackenkill road, lie in the 

 included angle of this spur. 



The contact is then easily followed southward by the steep mar- 

 ginal scarp in the limestone, from the point where the cross road just 

 mentioned makes its turn, to and across the Spackenkill road, and 

 east of the old Boardman farm. The gully which, as shown on the 

 map, cuts across this central strip west of the northern termination 

 of the narrow faulted strip lying on the east, may represent a fault. 



South of the Spackenkill road slates outcrop in numerous places 

 between the main strip and the narrow faulted mass just east and 

 south through the swamp to the southern end of the small strip, 

 leaving no doubt but that, at the surface, the two limestone masses 

 are separated by a narrow band of the slates. The eastern contact 

 is then very readily followed through the fields to Channingville 

 and then less distinctly under the drift between the creek and the 

 New Hamburg road to the bank of Wappinger creek near its junc- 

 tion with the Hudson. 



The western margin of the central strip could be determined with 

 much more exactness in certain places than in others. At the north 

 the surface deposits conceal it for the most part, but swamps and 

 other topographical features and occasional outcrops enable one to 

 follow it approximately, and in a few places distinctly, until it 

 crosses the Pleasant Valley road just west of Rochdale. The lime- 

 stone then forms a distinct scarp east of the road to the break just 

 southeast of Tompkins's house. South of this the margin is distinct 

 to the railroad, but across this it is soon lost under the drift com- 

 posing the large drumlin at this point. The limestone reappears 

 on the south side of this hill and again a Httle ' farther south as a 

 scarp which crosses the Poughkeepsie-New Hackensack roa;d. 

 South of this road the margin is readily followed, often with the 

 limestone and slate in close proximity, to the Poughkeepsie- Wap- 

 pinger Falls road which, going south, ascends the western scarp of 

 the Hmestone. South along the New Hamburg road the contact 

 is clearly for a distance on the east side of the road as the slate was 

 noted in the latter. But along here the kame deposits effectually 

 conceal the exact relationships between the limestone and slate. At 

 the northern end of the New Hamburg tunnel the limestone rests 



