38 



PRIMARY ROCKS. 



Igneous 



PS 

 ^< 



S 



Granite Composed of quartz, felspar and mica. 



Hyi'f'rsthrnf; rock. 



Primary limestone. 



Serpentine. ^ 



L Greenstone and trap. 



Plutonic <. Basalt. 



( Lavas. 



Gneiss Composed of quartz, felspar and mica. 



Micaslate Quartz and mica. 



Talcose slate Quartz and talc. 



Hornblende Simple. 



Sienite Composed of hornblende and felspar. 



Stratified--- 



Tho.se portions of the State over which Primary rocks prevail, are the Northern and 

 Southern liiglilands. Most of the masses enumerated ahove are found in both these 

 districts. In the northern, which is by far the largest and most important primary district, 

 that peculiar variety of granite denominated hypersthene rock prevails very extensively : 

 it forms the highest parts of the county of Essex. Surrounding this mass as an irregular 

 zone, are beds of granite, primary limestone, and a granitic gneiss. This immense mass 

 forms a large portion of the great triangle north of the Mohawk valley. It is here that 

 our granitic soils are formed. The beds, however, of granite and other felspathic rocks 

 which are disposed to decomposition are not very extensive. We have none of the sandy 

 varieties of gneiss or mica slate, which become friable on exposure to the atmosphere, and 

 crumble readily and rapidly into soil. Neither have we much of that peculiar granite 

 which forms porcelain clay, or it is so limited that mere local effects are observed. Primary 

 limestone, associated with granite, and even incorporated with it, exists also, but within 

 such narrow limits that it is unnecessary to notice the peculiar soil which is thus jointly 

 formed. The rocks on the highest parts of the .A.dirondacks disintegrate very rapidly, and 

 form deposites on the sides of these mountains, which in the progress of time find their 

 way to the valleys. 



In estimating the extent of granitic soil, and taking into account all the causes which 

 act in distributing it over the State, I am led to adopt the opinion that it exists only in the 

 immediate districts underlaid by the primary beds, in such quantity as to give the leading 

 characters of a granitic soil. Diluvial action has undoubtedly swept over these districts, 

 and carried to the south some of the soil which once rested upon the mountains and in their 

 valleys, and it has intermingled with other soils more or less ; still the quantity bears but 

 a small porportion to that derived from sedimentary rocks. It is true that the materials of 

 these rocks were in many instances of granitic origin, and it is easy often to discern unde- 

 composed felspar in them. Notwithstanding all this, I am not ready to subscribe to the 

 doctrine that all soils are essentially derived from one origin, and that a granitic one; for 

 most of the alkalies are lost in the course of the changes to which the fine particles are 

 subjected. No one, who has observed the soils of New- York, will hesitate to admit that 

 the slate soils are quite different from those of the highland districts. 



