Copper. 



225 



should have been produced in this greenstone ridge, or dyke, at the pe- 

 riod of its protrusion: certainly not without causing great disturbance 

 in the adjoining strata ; of which I have seen no traces. The con- 

 tinuity of this ridge is uninterrupted ; as are the dip and direction of 

 the sandstone strata. But the whole aspect of this valley, and espe- 

 cially the contour of Sugar Loaf, correspond with the idea of excava- 

 tion by water. The rocks in place too, on both sides of the river, to 

 the height of several hundred feet, bear the marks, in numerous 

 grooves, of powerful abrading agents. 



If such an hypothesis, however, be admitted, this work must have 

 been performed while the region under consideration was in a state 

 quite different from what it is at present ; and probably by other 

 streams than the Connecticut and its tributaries. For I have in an- 

 other place attempted to show, that these streams have not, to any 

 great extent, evcavated their own beds : although the reasoning which 

 proved this position, would not apply to the valley between Toby and 

 Deerfield mountain, except by way of analogy. If water did exca- 

 vate that valley, probably it was previous to the deposition of the ter- 

 tiary strata in the Connecticut valley; since no change of conse- 

 quence has taken place in the surface, (I mean by elevation or subsi- 

 dence,) subsequent to that period: whereas some change of this kind 

 must have taken place since the excavation of this valley, if other 

 streams than the Connecticut and it tributaries performed the work. 



But enough, and probably more than enough, upon a subject which 

 is obviously involved in great obscurity. I confess that the position 

 which I have taken, and the reasoning which I have advanced, do 

 not satisfy my own mind : but at present I can offer nothing better. 



Mineral Contents. 

 Copper. 



The veins of Copper ore, occurring at the junction of this forma- 

 tion with the greenstone, are the most interesting mineral treasure of 

 the new red sandstone; Here are found several species : viz. the 

 pyritous copper, red oxide, and green carbonate : and several 

 masses of native copper, have been found in the valley of the Con- 

 necticut, which propably originated in these veins. They are 

 quite numerous from New Haven to Northfield, and not unfrequently 

 extend into both rocks, the sandstone and the greenstone. Their 

 gangue is sometimes sandstone, sometimes trap, and sometimes sulphate 



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