A G R I C U L T UiR A L GEOLOGY. 185 



It Lansingburgh, there were 209. The number of cloudy days at the 

 ^ormer place was 122 ; at the latter, 111. These places are central 

 for the Taconic region, as it regards north and south. At Granville, 

 Washington county, in the north, there were 192 clear days, 174 

 :loudy, 51 rainy, and 16 snowy days. Towards the south, at Mount 

 Pleasant in Westchester county, it was clear 199, cloudy 166, rainy 

 107, and snowy 19 days. These observations are strictly in the val- 

 ey of the Hudson. The results would be different if observations 

 .vere made along the bases of the Taconic and Green mountains. 



Geological relations of the underlying rocks. 



The surface rocks, as a class, are slates, differing somewhat in 

 lurability, or power to resist the action of the weather. Those of 

 he valley of the Hudson are more disposed to decomposition than 

 hose of the eastern part of the district. Limestones and sandstones 

 brm only narrow and inconsiderable bells, running in the direction 

 »r parallel witli the mountains and hills. The following is considered 

 is a sufficient description of the rocks of this system. 



Skirting the valley of the Hudson, and the shores of Lake Cham- 

 tlain, a green slate constitutes the surface rock. It embraces a 

 ew thin non-fossiliferous beds of impure limestone ; besides which, 

 t is often traversed by thin seiims of calcareous spar. This slate is 

 iften fragile, and disintegrates easily ; and it forms an excellent 

 xgillaceous soil, though it contains some lime. At many points it 

 irops out beneath the Calciferous sandrock, one of the oldest rocks 

 f the New- York system. This belt of slate forms the surface rock 

 Imost fifteen miles in breadth ; or, it continues east to Canaan in 

 Jolumbia county, where it is succeeded by the Sparry limestone, a 

 ock which is about 500 feet thick. In composition, this slate is 

 omposed of silex, alumina and iron, with a trace only of magnesia 

 nd lime. Seams of white quartz are not uncommon. But this slate 

 oes not resemble in composition the Hudson river shales, although 

 ; is considered by many as identical with them. It contains more 

 lumina and iron, and much less lime and magnesia : the iron is in 



state of protoxide. Some inconsiderable patches or belts of it are 

 urgely charged with what appears to be a mixture of the hydrous 

 leroxide and the carbonate of iron. When composed thus, it forms 



deep red soil, which yields excellent grass for sheep or cattle. A 

 ilace opposite Catskill is of this description, and may be seen from 



atskill point. 



