lOi TEANS ACTIONS OF THE [FeB. 23 



limestone*. In another placef be speaks of the sandstone as 

 lying unconformably upon the primary. 



Brooks was led by his observations in Kossie, to conclude 

 that the limestone was conformable with the sandstone^, and, 

 therefore, of Lower Silurian, or, as it would now be called, 

 upper Cambrian age. The data upon which Brooks based his 

 conclusion seems to the writer unreliable ; for at Rossie the 

 limestone and sandstone are separated by considerable bodies 

 of iron ore and a peculiar serpentine rock of doubtful origin. 

 Until the true character of this member of the series is ascer- 

 tained, it is unsafe to base conclusions upon observations made 

 at that locality. 



North of Gouverneur the limestone and sandstone are in 

 direct contact, and opportunity is afforded for a study of their 

 relations. The evidence here presented, though often obscured 

 by the character of the rocks, indicates unconformity. From 

 the irregular line of contact it is clear that the material of the 

 standstone was deposited upon a limestone surface that had 

 been subjected to erosion. An interesting confirmation of this 

 conclusion is seen in the presence of narrow, irregular cracks 

 extending several feet into the limestone and filled with sand- 

 stone, ifvidently the limestone was completely lithified, and 

 not a calcareous ooze, when the sandstone was deposited upon 

 it, and this implies discordance. 



This unconformity j^roves only that the limestone is older 

 than upper Cambrian. For any more definite determination of 

 its age the data are wanting. 



Granite.— In the southern part of the area examined granite 

 forms a prominent ridge extending east and west. Besides this 

 main mass, there are many small patches breaking through the 

 limestone, some of these consisting of a pegmatitic variety. 

 Emmons' theory of the igneous origin of limestone was largely 

 based upon the character of the contact between the main body 

 of granite and the surrounding limestone. He regarded the 

 granite as a massive phase of the gneiss, and, holding the latter 

 to be sedimentary, was forced by the undoubted irruptive 

 contact between granite and limestone to look upon the latter 

 as igneous. Were the identity of gneiss and granite a fact, 



ready explanation of the origin of the former would be 



a 



* Geology of N. Y., 2(1 District, p. 53. 



t Fourtli Ann. Report, Geol. Survey of N. Y., p. 322. 



t American Journal of Science, iii., IV., p. 22. 



