40 Geology, &c. of the Connecticut. 
the rest. So that it does not, ] 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 bea different 
formation, which I have denominated the Coal Formation ; 
and which others have called gray wacke slate. Iknow o 
no instance in which | 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- 
ruptiy from an alluvial plain in the form of the frustrum of 
a cone, five hundred feet above the Connecticut; and the 
peak is called Sugar Loaf; being but a few rods in diame- 
ter at the top, and forming a striking 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. 
e 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 this passes imto and 
alternates with conglomerates of the same general charac- 
terand 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 
