GEOLOGY OF THE NORTH CREEK QUADRANGLE 7 



Quite typical Adirondack lakes and ponds are fairly abundant, 

 about thirty of them being represented on the map. The largest 

 is Schroon lake, only the southern end of which lies within the 

 map limits. The others range in size from small ponds to lakes 

 two or three miles long such as Friends and Loon lakes. 



From the geologic standpoint, the North Creek quadrangle is of 

 more than the usual interest because of both the rock types and 

 structures. With the single exception of the anorthosite, all the 

 important rock formations of the eastern Adirondacks are abun- 

 dantly represented. Except for the superficial glacial and recent 

 deposits, the rocks of the quadrangle are all of Precambric age, 

 and nearly all are highly metamorphosed, foliated, and folded. 



Following is a list of all the rock formations, except the Pleisto- 

 cene, given in the regular geological order of relative ages : 



5 Diabase : wholly nonmetamorphosed, occurring in comparatively 



small, narrow dikes, and clearly cutting all the other rocks of 



the region. 

 4 Pegmatite : wholly nonmetamorphosed, dikelike masses cutting 



all rocks except the diabase. 

 3 Gabbro: more or less metamorphosed, occurring in stocks or 



dikes and cutting all types of the syenite-granite and Gren- 



ville series. 

 2 Syenite-granite group : distinctly gneissoid rocks, representing 



several facies of a single great intrusive mass, and clearly 



younger than the Grenville. 

 I Grenville series : highly metamorphosed and foliated sedimentary 



rocks, including crystalline limestone, quartzite, and various 



dark to light colored gneisses. These are the oldest rocks 



of the region. 



In spite of the rugged character of the topography, the accessi- 

 bility of all parts of the quadrangle and the general excellence of 

 rock exposures have afforded an unusual opportunity for detailed 

 field work. Many important geologic relationships are very clearly 

 exhibited. 



1^'ollowing arc the principal papers which have a more or loss 

 direct bearing upon the geology of the (juadrangle : 



1842 Emmons. Geology of the Second District, N. ^^ 



1807 Komp & N'ewland. Preliminary Report on the GecMouy of Washington. 



Warren and Parts of Essex and Hamilton Counties. In 17th Annual 



Rep't N. Y. State Geologist. 



