40 Geology, fyc. of the Connecticut. 



the rest. So that it does not, I apprehend, occupy so much 

 of the surface, as is generally supposed. There is much 

 slaty sandstone, red and gray, and some of it very argilla- 

 ceous, found along this river, which does not appear to be 

 the old red sandstone of Werner ; but to be a different 

 formation, which I have denominated the Coal Formation ; 

 and which others have called gray wacke slate. I know of 

 no instance in which I am certain that decided old red 

 sandstone lies above the coal formation ; although they 

 evidently pass into one another. This coal formation, 

 with the secondary greenstone and alluvion, occupies, I 

 should judge, nearly two thirds of the secondary tract 

 along the Connecticut; leaving not more than one third for 

 the old red sandstone. This rock occupies the greatest 

 extent of surface, as the map will show, in the vicinity of 

 New-Haven. Along the western side of the secondary, it 

 may be found all the distance, (occasionally covered by 

 alluvion,) from New-Haven to Bernardston, Mass. Yet, 

 it forms but few ridges or peaks of much altitude until we 

 come to the south part of Deerfield. There it rises ab- 

 ruptly from an alluvial plain in the form of the frustrum of 

 a cone, five hundred (eet above the Connecticut ; and the 

 peak is called Sugar Loaf; being but a few rods in diame- 

 ter at the top, and forming a strilcing feature in the scene- 

 ry of the country. This is the commencement of a range, 

 which, five miles north, rises 700 feet above the adjoining 

 plain, and then slopes to the north, almost disappearing in 

 Greenfield ; but rising again in the northern part of the 

 town and sending off one or two spurs into Gill. 



The grain, even of the finest variety of this sandstone, 

 may be called coarse. Its colour is dark reddish, some- 

 times presenting spots or veins, of light gray, as in Hat- 

 field, Mass. Its cement is argillo-ferruginous, and the rock 

 usually exhales an argillaceous odour when breathed upon. 

 It contains a large quantity of light gray mica, the plates 

 being sometimes half an inch, or more, across, and insert- 

 ed promiscuously. This description applies to the finest 

 varieties of old red sandstone. But thi? passes into and 

 alternates with conglomerates of the same general charac- 

 ter and of various degrees of coarseness. The imbedded peb- 

 bles, vary in size from that of a musket ball to four or five 

 inches in diameter. They are usually quartz, felspar, graphic 



