54 Geology, ifrc, of the Connecticut. 



son to doubt that this fact may exist in this country a& 

 well as in Europe. Were I to refer to particular localities 

 for rocks resembling basalt, I should mention the foot of 

 Mount Tom on the north-east side, and a part of the range 

 passing through Deerfield. It would not surprise me, should 

 future geologists make a division of our greenstone, calling 

 a part of it basalt; dividing the upper part of the ridges from 

 the lower, or the eastern side from the western, or both. 

 A geologist, to be able satisfactorily to make these divi- 

 sions, or to decide whether any of our rock is basalt, ought 

 to have traversed extensively and observed minutely the like 

 rocks in Europe ; and, therefore, I leave the subject to 

 abler hands. 



A good locality for observing many of the varieties of 

 greenstone above described within a narrow compass, is on 

 the north bank of Deerfield river, about sixty rods from the 

 bridge. Let a person cross the bridge to the north, and 

 take the right hand road, until he comes to where the road 

 passes round the end of the greenstone ridge. Here he 

 will first see the most common variety, having a columnar 

 tendency ; and a few rods beyond, the reddish brown vari- 

 ety,* and in a wall, supporting the road on the right hand, 

 he will find abundance of the porphyritic greenstone, hav- 

 ing a somewhat stratified structure. Here, too, he will 

 find some specimens covered with a ferruginous coating ; 

 so much charged with iron, indeed, that efforts have been 

 made to smelt it. Indeed, a mass of four or five pounds 

 from almost any part of this greenstone range, when held 

 by the side of a compass, will move the needle. 



It is not always the case, nor even generally, that the 

 greenstone ridges that are marked as continuous on the 

 map, are strictly so. They are often composed of numer- 

 ous peaks or ridges, partially detached, but yet constitu- 

 ting a single range when viewed at their bases. And some- 

 times, when there appears to an observer passing along the 

 western side of the range to be an uninterrupted wall, clos- 

 er examination will show, that it is made up of several dis- 

 tinct ridges, so lapping on upon each other, and so near one 

 another, that they appear continuous. The mural face of 

 the ridges and hillocks is usually on their western side : 

 but sometimes on the opposite side, as in the high moun- 



*I have a specimen of greenstone from a vein in Scotland resembling this, 

 except that the Scottish rock is much coarser. 



