GEOLOGY OF THE REMSEN QUADRANGLE 



9 



to empty into the Mohawk river at Herkimer. Thus Black river 

 forms a part of the St Lawrence drainage system while West Canada 

 creek forms a part of the Mohawk-Hudson system. 



Another striking but well known feature of Black river is the 

 fact, that it follows close to the Paleozoic-Precambric contact for 

 many miles. Doubtless the character of the Paleozoic rocks (mostly 

 limestones) has had much to do with the determination of its course 

 along this line. 



The main tributaries of Black river within the map limits are 

 Big and Little Woodhull creeks on the north and Little Black creek 

 on the south. The main branch of West Canada creek on the north 

 is Town Line (Cincinnati) creek and on the south Black creek. 



Certain other topographic and drainage features are discussed 

 in the following pages. 



ROCKS OF THE REGION 



The rocks of the region include Precambric crystallines and 

 Paleozoic sedimentaries. Each of these rock classes occupies 

 approximately one half the area and they are separated on the 

 geologic map by a line running southeast and northwest. The 

 Precambric rocks represent a portion of the great Adirondack 

 crystalline mass along its southwestern border. The Paleozoic 

 rocks are of Lower Siluric age and overlap on the crystallines. 



Precambric rocks 



Grenville gneiss. Rocks of Grenville age comprise a series of 

 highly metamorphosed sediments and they occur in but one well 

 defined area within the map limits. This area, nearly triangular 

 in shape, covers several square miles and extends from Enos south 

 and southwestward. The best exposures are in the vicinity' of Enos 

 where for about a mile downstream Black river has cut a gorge 

 through the Grenville rocks which are finely exposed. Another 

 large outcrop may be seen where a road crosses Little Black creek 

 about a mile and a half from its mouth. Grenville rocks have been 

 found in many other parts of the region but they are so thoroughly 

 involved with syenitic masses that they can not be separately 

 shown on the geologic map. 



Where the Grenville rocks are found in considerable areas in the 

 northwestern Adirondacks, crystalline limestones are commonly 

 associated with them, and the limestone proves the original sedi- 

 mentary character of the formation. These characteristic crystal- 

 line limestones have not been found in the region here described. 



