388 Scientific Geology. 



twice as high as any other part of Worcester county. Its stratifica- 

 tion does not exhibit much of that irregularity, which we should sup- 

 pose must have resulted from its having been elevated so much above 

 the surrounding country: though its stratification is certainly very 

 obscure. And I am rather inclined to ascribe such an origin to this 

 mountain, than to suppose the surrounding country to have been once 

 equally elevated and subsequently worn away ; since the rock com- 

 posing it possesses no peculiar power of resisting disintegration and 

 abrasion, that is not possessed by the gneiss of the whole range. 



I would repeat here, however, a remark made under diluvium, that 

 the gneiss rock of Massachusetts appears to be peculiarly liable to 

 disintegration; especially where it abounds in sulphuret of iron. 

 Hence it is that the gneiss region of Worcester county furnishes so 

 excellent a soil. As we go westerly upon this range, and get into 

 the limits of Hampshire and Franklin counties, more of the naked 

 rock appears ; and the soil generally is much poorer. But in Wor- 

 cester county generally the rock appears in place but seldom ; and 

 the hills are much rounded. In the gneiss region of Hoosac Moun- 

 tain, that has been described, the hills are generally steeper, and the 

 country for the most part more elevated. The soil also is not as rich 

 or deep as in Worcester county. 



I have reason to believe, though not from personal examination, 

 that the Monadnoc and White Mountains in New Hampshire, are 

 essentially composed of gneiss, and insulated in a manner similar to 

 Wachusett : being in a continuation of the sam.e range. 



Porphyritic gneiss prevails extensively along the western margin 

 of the Worcester county gneiss range, in the towns of Northfield, 

 (Mass.) and Winchester, (N. H-) It appears also very conspicuously 

 on the high hill east of Ware Village. This is one of the most rocky 

 spots in the state ; and the crystalline masses of feldspar are here un- 

 usually large. This range of porphyritic gneiss extends northerly 

 through Dana, Petersham, &c., lying immediately east of the horn- 

 blende slate exhibited on the map. It can be traced south from Ware 

 also through Palmer, &c. Indeed, it is the most extensive deposit of 

 this variety of rock that I have ever found. It appears that the pe- 

 culiar causes that produced it, operated over a great extent. Judging 

 from the great regularity of the rock formations in this country, I pre- 

 dict that a strip of it may be found extending northerly from Long 

 Island Sound as far as the gneiss reaches. 



From Hubbardston, both north and south, to the boundaries of the 



