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NEW YORK STATE MUSEUM 



quartz, dark greenish brown hornblende and biotite. It presents 

 all the characteristics of the group of syenitic rocks from Loon 

 lake, referred to above under Caldwell. There is so much quartz » 

 present that the rock is really a granite, but we regard it as a 

 metamorphosed igneous rock belonging to the general group, 

 which Prof. Gushing has identified. 



The gneisses at the northern end of French mountain are sim- 

 ilar to these syenitic types, but differ enough to make one hesi- 

 tate regarding the identity. At the south end there is a change 

 however. Micaceous varieties with pegmatitic streaks are found, 

 and the same is true of the southeastern corner of the town of 

 Caldwell, but more complete observations would be necessary 

 in order to work out the relations. 



Of the paleozoic strata no Potsdam sandstone has been found 

 in the town, but it may exist beneath the later strata, having 

 been dropped out of sight by faulting. The Calciferous appears 

 along the east side of French mountain, as observed by Mr 

 Darton 1 and on the state map the entire valley, despite the 

 mantle of sand, is colored as Calciferous. This would seem to 

 be an error, as Mr Hill observed gneiss in the ridge which is 

 crossed by the first east and west road south of Brayton, and. 

 that meets French mountain near its middle point. The limita- 

 tions of the gneiss were not fully explored, and, indeed, there is 

 so much sand all through the valley that the hard geology is 

 largely a matter of inference. 



The Trenton strata occupy the southeastern corner of the 

 town and are well exposed in quarries at Glens Falls. Prof. 

 Prosser records 2 56^- feet of undoubted Trenton in the quarries 

 of Finch and Pruyn, with 2 additional feet of limestone of un- 

 certain affiliations at the base. In the south bank of the river 

 there is about 33 feet of higher lying beds, as shown by Dr 

 Prosser's section below the paper mill. 3 Mr Darton has also re- 

 corded the presence of a small outlier of Trenton beds along 

 the northeastern border about 2 miles south of East bay. Mr 



: 4Stli an. rep't X. Y. state museum. 1S94. 2:52. 

 -Bnl. X. Y. state museum no. .34. v. 7. p. 480. 

 3 p. 4S2. 



