GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 449 



vol., p. 299). The substance of the paper is, that this limestone has been 

 discovered to underlie a portion of the slate, and hence is thought to be 

 of the same age with it. The fossils were shown to James Hall, who 

 believed they might belong to the period of the Onondaga limestone of 

 New York ; at least, that they are not more ancient than that rock. 



Thus we fix the age of this day slate as a part of the Devonian system, unless there 

 is some mistake in the observations or the opinions as to their character. If this 

 result be admitted, it does not follow that all the rocks of the Green and White Moun- 

 tains are no older than fossiliferous rocks, as some maintain ; for the slate formation in 

 the Connecticut valley is manifestly a newer rock than those which succeed, either on 

 the east or the west. Perhaps it is a portion of the Hudson River slate, which once 

 arched over the intervening Hoosic mountain, and which has been subsequently worn 

 away, except in this deep valley. * * * j \13_yQ met nowhere with rocks more 

 thoroughly crystalline than those which constitute most of the White Mountain ranges. 

 Gneiss, mica slate, and hornblende slates, just such as you find in the central Alps, 

 constitute most of the White Mountain ranges. * * * We shall be cautious in 

 admitting a conclusion [that the New England rocks are as new as the paleozoic] which 

 goes to the very extreme of metamorphism, without decisive evidence. We should at 

 least wait till the White Mountains have been more carefully studied. 



Not far from this same year, the locality was visited by James Hall and 

 Sir Charles Lyell, but none of their publications add anything to what 

 has been already stated in this historical sketch. 



A fuller account, with a section, is given in the geology of Vermont, 

 based upon my father's and my own observations made in 1858. They 

 have been given essentially without change in the preceding description 

 of the section (Fig. 72). 



The fullest description of this region hitherto published was prepared 

 by Prof. J. D. Dana, and has been already alluded to. The facts of his 

 paper do not differ materially from my own, as given above, and I will not 

 quote his statements of the distribution and positions of the strata, but 

 present his conclusions. I feel very grateful to Prof. Dana for the interest 

 he has taken in this field. He perceived the true relations of the Coos 

 group to the mica slates of Bernardston before any one else; and it is a 

 pleasure to me to be able to confirm this conclusion by actually tracing 

 the Bernardston slates, ledge by ledge, to Chesterfield, and so on to 

 Haverhill, and finding them to be the same with what I have called the 

 Coos group in New Hampshire. If the Bernardston slates belong to the 

 VOL. II. 57 



