472 



Scientific Geology. 



show that such a succession of strata is found there, and that the mi- 

 ca slate and granite occupy a large proportion of the surface. 



The narrow range of granite extending from Amherst to the north 

 line of the State, occupies an intermediate level between the alluvial 

 bottom of the Connecticut valley, and the high ridge of gneiss bound- 

 ing that valley on the east. It is an extremely coarse granite, and 

 for the most part occurs in the form of veins or irregular masses in 

 mica slate and gneiss. And in some places these rocks very much 

 predominate and we lose sight of the granite. 



The patch marked as granite in the agillaceous slate of Guilford, 

 Vt., has been described in giving the mineralogical characters of this 

 ock. I would add, that the beds are somewhat numerous, although 

 but one is represented on the map, The deposit in Chester has al- 

 so been described. The range extending from Conway into Connec- 

 ticut, alone remains to be noticed. This occupies the space between 

 the sienite on the east, and the mica slate on the west. More or less 

 of the slate is intermixed with it through its whole extent; and on the 

 west, and towards the south, this slate abounds and predominates. 

 The strips of mica slate running into the granite, are intended merely 

 to indicate the fact that they do thus penetrate it, rather than to give 

 an exact representation of the particular places where this takes place. 



For the most part the granite of this range is very coarse. Not un- 

 frequently, how r ever, very coarse and very fine granite are associated. 

 In the granite patch extending from Norwich to Chesterfield, (and 

 which, implies only that beds are frequent in that region,) the rock is 

 coarser than any that I have found in the state ; the plates of mica 

 being sometimes a foot or a foot and a half across. It is these coarse 

 granite veins that are most prolific in minerals of an interesting char- 

 acter. 



For the most part this granite range occupies a low level : or rath- 

 er it is intermediate between the lowest and the highest of the rocks 

 on the western side of Connecticut river. Some of the granite hills in 

 Conway, Williamsburg, Whately, and West Hampton, rise higher 

 than any others of the same rock in the state. Their altitude, how- 

 ever, is only a few hundred feet ; and is far inferior to the hills of 

 mica slate lying immediately to the west. 



Upon the whole, all the granite of Massachusetts lies remarkably 

 low in respect to other rocks ; and one cannot avoid the inference 

 when he examines its situation in almost all cases, that the abrasion 

 of the stratified rocks may have brought the granite to light. 



