FOLIATION OF THE GNEISSOID SYENITE-GRANITE COM- 

 PLEX OF LEWIS COUNTY, NEW YORK 



BY A. F. BUDDINGTON 



The data and conclusions herewith presented are for the most 

 part abstracted from a report on the geology of the Lake Bonaparte 

 quadrangle, prepared at the request of the State Geologist. In its 

 preparation the writer was associated with Dr C. H. Smyth, jr. 

 Some additional information obtained subsequently by the writer 

 in a study of the geology of the Lowville quadrangle has also been 

 used. 



The origin and significance of the foliated structure in the gneisses 

 which constitute the Adirondacks have been discussed by many 

 writers in recent years, and widely diverse views have been expressed. 

 On the one hand, Miller 1 asserts a primary origin for the foliation 

 of the igneous gneisses and ascribes it to flowage phenomena and 

 crushing during the progress of consolidation of the magma, resulting 

 from the efforts of the igneous magma to shoulder aside blocks of 

 Grenville gneiss into which it is intrusive. He further states it as 

 his belief that " none of the published Adirondack maps or available 

 data afford any reasons to believe that the Grenville strata were 

 ever profoundly folded or compressed." On the other hand Smyth, 

 Cushing, and Martin have presented very strong evidence that 

 intense orogenic forces have acted upon the Precambric gneisses of 

 the northwestern Adirondacks, with the conspicuous result of 

 isoclinal folding. In particular, Martin 2 has studied and mapped 

 in great detail a great sigmoidal fold in the vicinity of Pierrepont. 



An intensive study of over six hundred thin sections of rocks 

 embraced within the area of the Lake Bonaparte and Lowville 

 quadrangles has furnished considerable new data bearing on this 

 problem. A brief summary of the data and the conclusions drawn 

 therefrom relative to the foliation of the syenite-granite gneissic 

 complex is presented here. For the most part they confirm Miller's 

 conclusions as to the primary origin of most of the foliation in the 

 igneous gneisses, but on the other hand they conform to the belief 

 that strong orogenic forces of mountain-building intensity have 

 affected the rocks of this district. 



1 Miller, W. J., Origin of Foliation in the Precambric Rocks of Northern New 

 York, Jour. Geol., 191 6, 24: 587-619. 



2 Martin, J. C, The Precambrian Rocks of the Canton Quadrangle, N. Y. 

 State Mus. Bui. 185, 1916. 



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