426 NEW YORK STATE MUSEUM 



part of Montgomery county and extends to the southeastward, 

 coming out in great force at Glens Falls where it is extensively 

 quarried for black marble. . . The lower massive series appears 

 to be an older member of the formation overlapped westward and 

 apparently to some extent near its southern termination by the 

 thin bedded series."^ This massive series is developed " in the 

 region about Amsterdam and eastward to the Hoffman ferry 

 fault. . . becoming somewhat thicker and coarser grained in 

 the easternmiost exposure. In the quarries and stream cuts north 

 of Amsterdam there are exposed 17 feet of the coarse grained mas- 

 sive series, here rather thinner bedded than usual. At the exten- 

 sive quarries [Weatherwax] two miles northwest of Hoffman ferry 

 the lower member is very coarse grained, soft, massive bedded, 

 highly fossiliferous limestone and has a thickness of about 20 feet " 

 (p. 426). 



TJtica shale. This mass is included with the Transition Gray- 

 wacke of Eaton as in part at least the slaty variety. ^ Mr Conrad 

 included the Utica in part with the Trenton, for he says ** the rock 

 is chiefly a fissile slate, but as it passes north it assumes as at Tren- 

 ton Falls the character of a dark blue, very hard fetid limestone. 

 . . The slate is frequently traversed by veins of calcareous spar."^ 



Vanuxem first spoke of the Utica as the black shale which appears 

 from under the rubblestone (Hudson river) and extends from east 

 to west throughout the county (Montgomery).'* 



Mather calls the Utica the Mohawk slate group and says that 

 it " passes into the Trenton by gradual interstratification."^ 



In the Fourth annual report of the third district Vanuxem says 

 " there is no mineralogical difference between the shale which 

 separates the dark colored layers of the Trenton limestone and this 

 rock, but though in many localities it contains thin beds or flags 

 of limestone in the lowest part of its mass, yet we often find above 

 these thin beds a thickness of two or more hundred feet without 

 any limestone whatever."^ 



In Vanuxem's final report this rock is designated " Utica slate," 

 and is described as *' of a deep bluish black, generally fissile, ex- 



^13tli annual report N. Y. state geologist, 1893, p. 424, 42S. 



-Geological survey district adjoining Erie canal, p. O'l. 



^Pirst annual report third district (N. Y.) Assembly doc. no. 161, p. 163. 



*Second annual report third district, Assembly doc. no. 200. p. 258. Sec also p. 283. 



^Fifth annual report first district, Assembly doc. no. 150, p. 91, 92. 



^Loc. cit. Assembly doc. no. 50, p. 371. 



