392 DARTON GREEN POND, N. J., TO SKUNNEMUNK MT., N. Y. 



crystalline rocks and Hudson shales two miles northwest of Monroe, as 

 shown in figure 2, the supposed Oriskany quartzite quite clearly overlaps- 

 Along the eastern side of Woodcock hill there is the fault and no ex- 

 hibition of the overlap is seen at the surface. Along the base of the next 

 Archean area south of Woodcock hill the quartzite appears to lie on the 

 uneven surface of the gneiss without possibility of an intervening fault. 



The Monroe shales lie in conformable sequence on the Oriskany beds 

 in New Jersey, except just south of the southern end of Greenwood lake, 

 where the quartzite may be lacking for some distance. They are very 

 sharply separated by an abrupt change in the character of their mate- 

 rials, but present no special evidence of unconformit}^ There may pos- 

 sibly be a general break in the sequence in this region, represented by 

 Caudi Galli shales and Onondaga limestone westward. North of Green- 

 wood lake for many miles they appear to lie on the Cambrian limestone to 

 the eastward, excepting for a short way southAvest of Monroe, where they 

 probably overlap on the crystalline rocks, although they are not exposed 

 in contact. In the vicinity of Monroe and northward for some distance 

 they appear to lie on the Cambrian limestone again, but their contact is 

 covered by heavy drift. In Pine hill they lie on Helderberg limestone, 

 but appear to overlap on the Cambrian limestone or even the crystalline 

 rocks, northward for some distance. There is the possibility of a fault 

 in this vicinity between the limestone and Monroe shales, but there is 

 no positive evidence on this point. In Pea hill, near Cornwall Station, 

 the shales lie in conformable succession on the Oriskany quartzite. Along 

 the western side of Skunnemunk mountain they lie directly on Oriskany 

 quartzites at several localities, and in the intervals, on Hudson shale and 

 Cambrian limestone, but from the latter they may possibly be separated 

 by a fault. Northwest of Monroe they overlap widely to the westward, 

 as shown in figure 2, and are in contact with Oriskany, Helderberg, 

 Hudson, Cambrian and Archean in succession. Along the west side 

 of Bellvale mountain they are underlain by two lense-like masses of 

 Oriskany quartzite and one of Helderberg limestone, and are in con- 

 tact with Hudson shales, Cambrian limestone and Archean rocks in suc- 

 cession, possibly with a separating fault. Southward along the western 

 side of Bearfort mountain they are cut out, in all probability by a fault 

 as shown in sections VI, VII, and VIII on plate 17. They come out 

 again in the wide synclinal region north of Milton and abut against the 

 crystalline rocks, from which they are probably separated by the fault. 



No overlap of Bellvale flags or Skunnemunk conglomerate are known, 

 unless the contacts with the gneiss west of Bearfort mountain and on the 

 southern end of Bellvale mountain are due to overlap and not to over- 

 thrust. 



