302 



Scientific Geology. 



the rock ; and which is liberated in a gaseous form by friction or a 

 blow. The odor is commonly said to be that of sulphuretted hydro- 

 gen; though I confess I do not perceive much resemblance. But 

 even if this be the case, putrescent animal matter would furnish this 

 gas abundantly. And if we adopt the opinion maintained by some 

 very able geologists, that all, or nearly all limestones were produced 

 from living beings, we can easily understand whence this animal 

 matter proceeded. 



In general the strata of the Berkshire limestone have a dip towards 

 the east, between 15 and 30. In some instances it is greater ; and 

 Prof. Dewey, from whose account of the Geology of Berkshire, in 

 the American Journal of Science, I have derived much assistance, 

 says, that at the base of Saddle mountain, on the northwest side, some 

 of the limestone dips to the west, and some is perpendicular, although 

 the prevailing dip is to the east. He has given also, in the same 

 work, a drawing and description of a singular conformation of the 

 limestone strata near the College in Williamstown.* Not improba- 

 bly this is only an example of a concretionary structure on a large 

 scale; though possibly it might have resulted from mechanical agen- 

 cies in early times. 



I have never seen either a mass of granite or of trap, or any other 

 unstratified rock, in contact with this limestone ; though not improba- 

 bly such junctions may be found. The following is a sketch of the 

 shifting of a vein of white carbonate of lime, in a slab of light gray- 

 marble, five feet long and three feet wide, taken from a quarry in 



New Ashford. a, a, is the vein of the carbonate of lime, and d d, a 

 somewhat wedge shaped mass of dark gray limestone, five inches 

 wide at its base, which is twice cut off, once by each separate portion 



* Vol. 9. p. 19. 



