506 



Report of the State Geologist. 



The smaller streams, the Little Chazy, Salmon and Little Ausable rivers 

 are wholly or mainly in post-glacial channels, and give little cine to the minor 

 pre-glacial drainage. Such part of the county as is most suitable for agricul- 

 tural purposes is mainly confined to this strip, and on it are many fine farms. 



General Geologic Relations. 



Professor J. F. Kemp has recently published a resume of the schemes of 

 classification which have been proposed for the rocks of the Adirondack 

 region, to which he has added a tentative one of his own.* 



This, which comprises: 



(I.) A basal gneissic series. 



(II.) A series of schists and gneisses with crystalline limestone. 

 (III.) Igneous rocks of the gabbro type. 



(IV.) Palaeozoic sediments, lying unconformably on the first three. 



(V.) Igneous, rocks found as dikes cutting all the foregoing, and 



(VI.) Pleistocene deposits ; 

 will be followed in this report, emphasis being laid on the fact that it is 

 tentative, and probably simpler than the one finally adopted is likely to be. 

 The writer has elsewhere given reasons for holding that this scheme must 

 be expanded by the insertion of another period of dike formation between 

 (III.) and (IV.).f 



As exposed in Clinton county these subdivisions may be epitomize* 1 as 

 follows: 



Series I. The oldest rocks visible so far as known belong to a great 

 series of gneisses and are well shown in all the western tier of townships 

 except Clinton, and in Peru and Ausable. In their typical development they 

 are easily recognized. They present well-marked varieties, as below, all of 

 w hich seem to grade into one another. 



1. Gneisses, commonly of red color, but also grey, brown, and other 

 shades, composed mainly of microperthitic orthoclase and quartz. Occasion- 

 ally these are the only constituents, when the gneissoid structure retreats 

 and a red granite rock results which seems to be merely a phase of the gneiss. 

 There lias not yet been found in the county a granite which can be shown to 

 be intrusive in the gneiss, like that described by Smyth in St. Lawrence and 

 Jefferson counties. More commonly one or more of the minerals magnetite. 



* J. P. Keni|>, Report New York State Geologist for 1898, Vol I., pp 444-447. 



t II. P. Cashing, Transactions New York Academy of Sciences, Vol. XV., pp. 348-352. 



J < '. II. Smyth, Jr , Transactions New York Acailemy of Sciences, Vol XII , pp x'OS to 812. 



