236 The Physical History of the Trias 



tain strata and the shale takes its place. * * * This conglom- 

 erate is seen along the river for a distance of two miles." 

 Further on in the same description, Prof. Cook mentions that 

 " The vertical section along the river exposes a thickness of 

 between two hnndred and three hundred feet of conglomerate 

 and interstratified shales." 



We cannot agree with some geologists who have held that 

 this conglomerate is a peculiar and distinct deposit capping the 

 red sandstone series. On the other hand, it seems very evi- 

 dent that it was formed contemporaneously with the beds of 

 shale and sandstone with which it is associated, and may have 

 accumulated at many distinct horizons in the Triassic series. 



While examining the geology along the banks of Minne- 

 scongo Creek, in Rockland County, ~H. Y., I had an opportu- 

 nity of testing these views in reference to the origin of the 

 variegated conglomerate. Tracing this stream from where it 

 empties into the Hudson near Stony Point, northwestward 

 towards its source in the Highlands, I found it first flowing be- 

 tween banks of sand and clay, which form a terrace along the 

 banks of the Hudson. Following up the stream, a fine exposure 

 of the the Triassic shales is soon reached, near the little village 

 of Stony Point. The banks are here about fifty feet high, and 

 show interbedded layers of compact light-colored limestone, the 

 most continuous of which is about fourteen inches in thickness. 

 A few hundred yards above this, the stream comes down in a 

 series of small cascades, which' fact indicates at once that a 

 change has occurred in the geology of its bed. On examina- 

 tion, I found that these rocks were unmistakably a portion of 

 the series of variegated conglomerates, of which we have spoken. 

 The nature of this deposit is beautifully shown, both in the 

 bed of the stream and in the banks on either hand. The rock 

 is a coarse breccia from 150 to 200 feet thick, composed of frag- 

 ments of limestone and granite rock derived from beds in the 

 upper portion of the valley, imbedded in a paste of red argil- 

 laceous material. Where this deposit is first met with in going 

 up the stream, the red cementing material is more abundant 

 than it is farther above, and the beds of cono-lomerate — breccia 



