REPORT OP THE STATE PALEONTOLOGIST 1902 935 



distance, to plunge three times over precipices caused by the 

 rocks in question and to form the waterfalls, a part of whose 

 great water power is utilized now in the mills of Schaghticoke. 

 The outcrop is totally isolated, there being an interruption of 

 three quarters of a mile to the outcrops farther above the river, 

 near the powder mills of Valley Falls, the interval being filled 

 by drift. Likewise the Schaghticoke beds are separated by a 

 drift-filled interval from the masses of shales and heavy banks 

 of " Hudson grit," exposed a little farther down the river. There 

 is no doubt that the latter mass, which contains graptolites of 

 the upper half of the Lower Siluric, is separated from the beds 

 at Schaghticoke by a great fault, probably the same which 

 farther south, for instance at Rensselaer, separates the Cambric 

 and Trenton shales. 



The Schaghticoke slates disappear also north and south of 

 the river banks under great drift masses and do not reappear 

 for considerable distances. It is however very probable or 

 almost certain that they represent a continuation of the belt 

 of Cambric rocks (shales, slates, quartzite and limestones) which 

 are well exposed on the hills east of Troy and have become well 

 known by Ford's discoveries of fossils. This belt has been 

 traced and mapped by Walcott, 1 as extending as far as the Deep 

 kill and been found by the writer to continue in fossilifer- 

 ous beds still farther north, east and northeast of Melrose to 

 within a few miles of the outcrop at Schaghticoke. As the lat- 

 ter lies also in the direct strike of these Cambric beds, it is 

 fairly to be concluded that it is a northward continuation of that 

 belt. 



The Cambric beds of the slate belt of eastern New York have 

 thus far furnished only fossils of the Lower Cambric or Georgian 

 formation. The Dictyonema beds will, as we may anticipate, be 

 shown to be equivalent to the highest Upper Cambric beds and 

 may, hence, in a general way be said to represent part of the 

 off-shore deposits of the Potsdam or Upper Cambric formation. 



The entire mass of rocks, exposed for about half a mile in the 

 gorge of the Hoosic river at Schaghticoke, consists of very fine 

 bedded, black and prevailing dull greenish to olive silicious and 



'Am. Jour. Sci. 1888. v. 35, pi. 3. 



