8 A GEOLOGICAL HISTORY. 



the soil which he is cultivating — practical men 

 have often found out that soil* which is most con- 

 genial to the plants they intend to raise, but with 

 the knowledge of Geology, their strength would 

 be supported, and their practice made more perfect. 

 The soil which produces in the greatest abund- 

 ance, wheat, (the staff of life,) appears to lie be- 

 yond the Alleghany Mountains : in the state of New 

 York it is underlaid by what is now called the " Si- 

 lurian system of rocks :" these rocks consist of 

 Limestone and Sandstone, and shaley clay, impreg- 

 nated with lime, and some Gypsum, and are great 

 beds of shells, which appear, as if they were once at 

 the bottom of some ocean — the soil lying on the top 

 of these rocks, is the most prolific to the farmer, 

 in its products of grain and grass. 



Even to the well-digger, a certain knowledge of 

 the dip and make of the rock is requisite, that he 

 may know how deep he must descend, and whether 

 water can be obtained, and if attainable at all, at 

 what spot. I have known well-diggers to pass 



* On the warm, sandy soil of south New Jersey and Long Island, you 

 can raise the sweet potatoes, (Convolvulus Batata,) although this plant, 

 growsrnore luxuriantly in more southern latitudes. I have known these 

 potatoes to grow from 12 to 16 inches long on the sandy soil of New York 

 Island, on the farm of J. M. Bradhurst, Esq., 9 miles north from the City 

 Hall, on the Kingsbridge road, while as far south as the city of Wash- 

 ington, in a clayey soil, they did not grow much longer than one's finger. 



