AGRICULTURAL GEOLOGY. 7 



and fanciful hypotheses, which every man has a right to invent for 

 ihis own or his neighbor's amusement. But such cavilers belong 

 to a race too lazy to observe, too self-conceited to profit by facts, 

 or too bigoted to look at truth when they fear it may conflict 

 with their own notions. They are too obstinate to be reformed ; 

 and if they were reformed, they would be of little use to science 

 in any of its departments. 



The primary rocks, comprehending granite, hypersthene, pri- 

 mary limestone, serpentine, gneiss, mica and talcose slates, horn- 

 blende, sienite, trap and greenstone, require our attention first of 

 ill. They may be tabulated as follows : 



/"Granite Composed of quartz, felspar and mica. 



iGXEOcs \ Hypersthene rock. 



j Primary limestone. 

 ^ [Serpentine. 



p5 r Greenstone and trap. 



<J { Plutonic \ Basalt. 



S (Lavas 



2 r Gneiss Composed of quartz, felspar and mica. 



ft Mica slate Quartz and mica. 



Stratified.. . i Talcose slate. . Quartz and talc. 

 Hornblende... Simple. 

 . Sienite Composed of hornblende and felspar. 



Those portions of the state over which primary rocks prevail, 



,re the northern and southern highlands. Most of the masses 



Inumerated above are found in both these districts. In the north- 



jrn, which is by far the largest and most important primary dis- 



rict,that peculiar variety of granite denominated hypersthene rock 



(revails very extensively : it forms the highest parts of the county 



f Essex. Surrounding this mass as an irregular zone, are beds 



t granite, primary limestone, and a granitic gneiss. This im- 



iiense mass forms a large portion of the great triangle north of 



|ie Mohawk valley. It is here that our granitic soils are formed. 



'he beds, however, of granite and other felspathic rocks which 



disposed to decomposition are not very extensive. We have 



pne of the sandy varieties of gneiss or mica slate, which become 



lable on exposure to the atmosphere, and crumble readily and 



ipidly into soil. Neither have we much of that peculiar granite 



hich forms porcelain clay, or it is so limited that mere local 



pets are observed. Primary limestone, associated with granite, 



U even incorporated with it, exists also, but within such narrow 



jnits that it is imnecessary to notice the peculiar soil which is 



us jointly formed. The rocks on the highest parts of the Adi- 



