64 Geology^ ^c. of the Connecticut, 



dip. The distances were all estimated by the eye, but it is 

 presumed they will in general be found not far from the truth. 

 From No. 1 to 56, inclusive, the stratified rocks all dip to 

 the east, as is evident from the section. The Nos. included 

 in parenthesis, refer to the general descriptions of the rocks 

 of the coal formation in the beginning of the article. 



No. 1. Horblende Slate — Strata highly inclined, often be- 

 coming an aggregate of hornblende, quartz and mica, having 

 a porphyritic aspect. 



No. 2. Mica Slate — Dip 20° to 30°, undulating and tor- 

 tuous, passing on the east into argillite. 



No. 3. Limestone — In beds in mica slate, already descri- 

 bed in the preceding pages. Unstratified. 



No. 4. Argillite — Dip 60° to 90°. The southern limit of 



this rock hardlj reaches the line of the section : but a mile or 



two north, its relative position is as represented on the profile. 



No. 5. Old Red Sandstone — With red conglomerate. Dip 



usually as much as 20°, being greater than is usual for this rock. 



No. 6, Alluvion — A swamp. 



No. 7. Old Red Sandstone — Dip between 20° and 30°. 

 No. S. Secondary Greenstone — It is probable this forms 

 a bed between the old red sandstone and the coal formation : 

 but the former rock is never seen passing under it in this vi- 

 cinity ; and, therefore, it must not be thus represented on 

 the profile. Width about half a mile.- On the eastern side it 

 has, for a few feet in width, somewhat of a stratified structure. 

 No. 9. Red, Fissile, Friable, Argillaceous, Sandstone, 

 Slate — (No. 3.) It is fine grained and often micaceous, of 

 the color of brick, is easily cut by a knife, yields an argilla- 

 ceous odour, has an undulating surface generally, and is liable 

 to disintegration. This is probably the most abundant of 

 the rocks of the coal formation; and it usually lies next to 

 the greenstone and alternates with it. It is found over a 

 large extent of country on the east side of the greenstone 

 ridge, stretching from Amherst to Berlin; although in Con- 

 necticut it more frequently is wanting in the mica and its 

 surface is more uneven. It forms much of the flagging 

 stone in Hartford and exists in place a foot or two below the 

 surface in that city; though it seems here in some instances 

 to approach to the nature of shale. The surface of the lay- 

 ers often appears a little glazed and is sometimes traversed 

 by numerous little ridges a mere line in thicknes and of the 



