230 



Scientific Geology. 



to, we find the anomaly which is here sketched. It is a satisfactory 

 explanation of this case to suppose that greenstone, or some other 

 igneous rock, has pressed upwards with such force between A and E, 

 as to give the the strata a saddle shaped appearance for a few r rods. 

 (Four rods from A to E.) If this hypothesis be correct, we can 

 hardly conceive, as in the case at Berlin, why the bitumen is not ex- 

 pelled from the coal. Upon the whole, the cases that have been men- 

 tioned show, that something more than mere proximity to rocks of 

 igneous origin is necessary for the conversion of bituminous coal 

 into anthracite ; although heat is undoubtedly the principal agent. 



Generally the coal that has been described, occurs in a gray coarse 

 micaceous sandstone. But at the locality at West Springfield, it is 

 found in bituminous mariite. At Sunderland, it is in bituminous 

 shale. 



Lead, Zinc, and Iron. 



The sulphurets of these metals occur in a vein at the junction of 

 the greenstone and this formation, in Berlin, Ct. as described by Dr. 

 Percival. Galena and Blende, I have observed in small quantities in 

 the fetid limestone of West Springfield, at Paine's quarry, and blende 

 at Meachem's quarry. Sulphuret of iron is quite common in the shale 

 every where. Nodular argillaceous iron ore also occurs in the same 

 rock, at Turner's Falls, South Hadley Canal, &c. The carbonate of 

 iron at Turner's Falls, has been already described : and I suspect 

 No. 241 to be the same mineral from South Hadley Canal: though 

 it resembles cinnabar. But the chemical tests do not indicate the 

 presence of mercury. Yet from its solution in nitro-muriatic acid, 

 prussiate of potash threw down a dense precipitate of the prussiate of 

 iron. 



Iron Sa?id. 



Bushels of this substance, highly magnetic, may sometimes be col- 

 lected on the Montague shore of Connecticut river, 40 rods below 

 Turner's Falls. Probably it proceeds from the disintegration of the 



