Geology, fyc. of the Connecticut. 71 



The highest point of the coal formation is Mount Toby 

 in Sunderland, which rfses between eight and nine hundred 

 feet above the Connecticut. Beginning at Whitmore's fer- 

 ry, the locality of the ichthyolites, to be hereafter described, 

 and passing up the mountain obliquely to the south-east,we 

 find alternations of most of the rocks described in the above 

 profile. The diiferent varieties of conglomerate are most 

 abundant, and cannot, except that variety which is reddish, 

 be easily confounded with the conglomerate accompanying 

 the old red sandstone. They differ from this latter rock, 

 1, By being of a light or dark grey color, sometimes a 

 little red. 3. In the greater abundance of imbedded no- 

 dules, and less quantity of cement. 3. In the different na- 

 ture of these nodules, those in the old red sandstone con^ 

 glomerate being chiefly quartz, felspar and granite, and 

 those in the coal formation pudding-stone, being chiefly 

 mica slate, argillite, chlorite slate, talcose slate, and quartz 

 with felspar and granite rarely. 4. The coal formation 

 pudding stone often contains thin incrustations of carbo- 

 nate of lime in the seams and crevices. The red sandstone 

 is wanting in this. 



As a general fact, I feel prepared to state that the rocks 

 of the coal formation lie above the old red sandstone. In 

 most cases these rocks are separated by greenstone, so that 

 their exact situation cannot be easily ascertained. Along the 

 western face of the greenstone ridge, extending from Mer- 

 iden into Massachusetts, the rocks of the coal formation are 

 often seen cropping out below the greenstone ; and the old 

 red sandstone occurs at a still lower level. This may be 

 seen in the space of a few rods in descending the hill nor- 

 therly, from Newgate prison ; and although the actual junc- 

 tion of the rocks is not here observable, yet they appear 

 only at short distances from one another. The fact, that 

 the coal formation alternates with greenstone, and that this 

 latter rock always lies above the old red sandstone, is a 

 strong presumptive argument that all the coal formation 

 lies above the old red sandstone.and conclusive evidence that 

 a part of these rocks lie above it. The situation of the rocks 

 about Middletowii, Chatham, &c. which might be urged 

 as an objection to this fact, has been already considered, 

 and I leave it for further examiJiation, 



