424 NEW YORK STATE MUSEUM 



a mile below Amsterdam. . . Some of the layers at Amsterdam 

 are referable to this mass as well as a large portion of the rock 

 quarried at Schelpintown [Rockton]. In all these localities the 

 color of the rock is gray, lighter or darker in some than in others, 

 has a crystalline grain, rather tough. . . Some portions contain 

 knobs, the result of accretionary action (p. 43). 



Then follows a detailed description of the " rock at Stanton's 

 quarry " (p. 44). 



In the final report of Emmons the Black river Hmestone receives 

 the name of "Black marble of the Isle la Motte" and is characterized 

 as the mass between the Birdseye and Trenton limestones, separated 

 into several layers and having a total thickness of about 12 feet* 

 It is often known as the Seven foot tier and is often lumpy. The 

 fossil Columnaria sulcata is said to be quite abundant 

 at Watertown, Glens Falls and Chazy.^ In the volume on agri- 

 culture the designation of this rock is " Isle la Motte marble," and 

 its thickness is given as " 25 or 30 feet " at Isle la IMotte and 

 " 7 or 8 " at Watertown where it is said to be lumpy.^ 



•Mr Darton makes very little mention of the Black river lime- 

 stone but states that: 



In a small area near Amsterdam and in the Glens Falls 

 region the Black river beds appear to be represented together 

 with a heavily bedded member at the base of the Trenton. In 

 a small stream emptying into the Mohawk opposite Amsterdam 

 there is a three foot bed of coarse limestone of dark gray color 

 containing corals, including Columnaria alveolata which 

 I believe represents the Black river horizon.^ 



Trenton limestone. Prof. Eaton in 1824 described this rock mass 

 under the name of " metalliferous limerock " as a compact, gray, 

 sometimes slaty, frequently cellular rock containing calcareous spar 

 in scales and abundant fossils.^ The region under consideration is 

 mentioned among the localities of rock (p. 81). 



In the First annual report on the geological survey of the third 

 district the Trenton is called " Blue fetid limestones and shales of 

 Trenton falls " with a thickness of about 400 feet. It is evident that 

 part at least of the present Utica formation is included under the 



^Geology of New York, pt 2, p. 110, 111. 



'Agriculture of New York, 1:123. 



813th annual report N. Y. state geologist, 1893, p. 424. 



^Geological and agricultural survey district adjoining Erie canal, 1824, p. 33. 



