PuOSSKR AND CuMINGS — -LoWEII Si I.I KI AN SECTIONS. 



limits of the exposure — a small quarry — this limestone varies from two to 

 four feet in thickness, both delimiting terranes being in place. The upper 

 surface of the subjacent Caleiferous sandrock is irregular, and the line of 

 contact between it and the overlying Birdseye very sharply defined. Above, 

 the Birdseye seems to pass into the superjacent Black river limestone without 

 any sharp line of demarkation. 



The base of the Trenton formation in this section is approximately -'580 

 feet A. T., while in the exposure west of the Eva's kill, one and one-half miles 

 north, the base of this formation is 600 feet A. T. This gives a south dip of 

 147 feet per mile. 



Hoffman and Van Epps Hill Section. 



Just west of the railroad station, at Hoffman, Schenectady county, is a 

 conspicuous cut on the New York Central railroad, in which the Caleiferous 

 sandrock is well exposed. The base of the cut is about twenty feet above the 

 Mohawk river. A section, beginning at river level and extending to the top 

 of Van Epps hill, is as follows : 



II A 1 . Massive, thick-bedded, steel grey, arenaceous, buff- .H )() Fce |< J0 

 weathering limestone or calcareous sandstone; the lower twenty feet covered 

 beneath the railroad, and forty-eight feet immediately succeeding, exposed 

 in the cut. Above the cut, partly covered. The joints and seams of this 

 rock are often tilled with calcite, and some chert occurs. 



A*. Top covered for the most part; base consisting of dark blue, ( ; F V r '- 

 moderately fine-grained, arenaceous limestone, w ith weathered surface marked 

 by plant-like reticulations which weather yellowish, exposed in the roadside at 

 an elevation of 350 feet above river level. Fucoidal division of the Caleiferous. 



A : \ West of the Schenectady-Montgomery county-line road, at 



Peel 



355 



an altitude of 350 feet above river level, is a live-foot bed of compact lime- 

 stone, containing ;i large specimen of Cohimna/i'ia al/veolata near the base. 

 Black river limestone. 



J 4 . In the fault escarpment, a. short distance to the northeast of :i0 } '" : j S - 

 the exposure of No. 3, is another of about twenty-five feet of thin, hard, 

 dark-colored layers, containing Trenton fossils including Trwucleus concert- 

 tricus. These layers rest directly upon thick layers of Caleiferous sandrock, 

 and from this fact and their strong dip, it is probable that they were displaced 

 from their normal stratigraphic position in the faulting. In the open field 

 ^ast of the highway, opposite the exposure of Black river, and at an altitude 

 of about 350 to 355 feet, is a small exposure consisting, at the top, of three 



