Geology, fyc. of the Connecticut. 33 



these slates has been long since given to the public by Prof. 

 Sillimaii in President Dwight's Statistical account of New- 

 Haven, page 11. Their strata run N, E. and S. VV. and 

 dip to the S. E. The angle of depression below the 

 horizon rarely exceeding 30° or 40°. 



Let hand specimens of this primitive greenstone and of the 

 secondary greenstone from East or West Rock be exhibited 

 to a geologist who had never visited the localities, and he 

 would not hesitate, I think, to pronounce that from East and 

 West Rock to be primitive, and the other to be secondary; 

 and for the reason, that he would find the secondary green- 

 stone to be much the coarsest and most crystallme. The 

 primitive greenstone of this locality is finely granular, and 

 agrees, in this respect, with Jameson's description of transi- 

 tion greenstone. Indeed, it has already been suggested (Jour- 

 nal of Science, Vol. 2. p. 165.) that the Verd Antique of Mil- 

 ford may possibly belong to a transition series ; and il so, this 

 greenstone, greenstone slate, and chlorite slate, and even 

 that bastard mica slate which is sometimes four.d between 

 this marble and the secondary, may belong to the same class. 

 The finely granular texture of transition greenstone, is how- 

 ever, by no means a distinctive character: since both the 

 primitive and floetz greenstones are described as possessing 

 the same. 



The range of primitive greenstone in Northfield and Gill, 

 commences about two miles north of the northern termination 

 of secondary greenstone, and extends into Vernon. Its char- 

 acters are very similar to those of the same rock at Whately and 

 Milford. Some of it however approaches rather nearer the na- 

 ture of sienite : but still the hornblende predominates. It is of- 

 ten stratified and often semi-stratified, becoming greenstone 

 slate. Near the southern point I observed a vein or dike of 

 limpid quartz several rods long and one foot wide, traversing 

 this rock, having, a part of the distance, saalbandejs of felspar.v 



The primitive greenstone occurring in Whately is some- 

 what different in its characters from that in Milford. It is 

 coarse and usually highly crystalline in its texture, being some- 

 times rendered almost porphyritic by the imbedded oeioes 

 of compact felspar, and sometimes being little else than pure 

 hornblende. It is not extensive and alternates in one in- 

 stance with sienite, the locality of which has been pointed 

 out in treating of the latter rock. 



V0L.VI....N0. I. 5 



