12 Economical Geology. 



nant ingredient is a rather fine whitish sand ; and sometimes beds of 

 extremely pure sand are found in it ; as in Pelham and Shutesbury. 

 Indeed, the appearance of the soil from gneiss, indicates uncommon 

 poverty and sterility. But facts do not correspond to this anticipation ; 

 for in no part of the State do we find finer looking farms, or the ap- 

 pearance of more thrift and independence among their occupants, than 

 in the region where gneiss prevails : I refer chiefly to Worcester 

 County, most of which is based on this rock. The western part of 

 the range, however, embracing the eastern part of Franklin, Hampr 

 shire and Hamden Counties, is in general characterized by a rather 

 barren soil. But this region is more elevated than the surface farther 

 east. Where it is not so high, as in Monson and Brimfield, we find 

 the same appearance of fertility as in the towns farther to the east. 

 It is a question worthy of attention, however, how far the soil from 

 our gneiss-rock may owe its agricultural character to the iron that so 

 generally accompanies this rock. Certainly the iron gives it an apr 

 pearance of sterility which does not belong to it 



Greenstone. 



This is one of the varieties of rock embraced under the general 

 term trap rock. The variety most common in Europe is basalt : and 

 the soil produced by its decomposition is said to be of a superior qual- 

 ity. The greenstone of Massachusetts, however, except some of its 

 rarer varieties, is but little acted upon by ordinary decomposing and 

 disintegrating agents ; and is proverbially one of our hardest and 

 most indestructible rocks. Hence the soil that covers it is generally 

 quite scanty. It is, however, very peculiar ; and we find upon our 

 greenstone ridges, quite a number of plants, shrubs, and trees, that 

 are not found, except rarely, upon the other formations. The eastern 

 part of the County of Essex is in a great measure composed of green- 

 stone ; and its superior agricultural character, in general, produces a 

 favorable opinion as to the influence of this rock upon the soil, though 

 very much must be imputed to good management. This formation in 

 the Connecticut valley furnishes but little arable land, and that of rath- 

 er a sterile character. 



Porphyry. 



This rock offers but little interest in an agricultural point of view. 

 It is of quite limited extent and is decidedly the hardest and most un- 

 yielding of all our rocks. It occupies the greater part of the surface, 



