396 STRATIGRAPHICAL GEOLOGY. 



spoken of east of Stony brook, as well as to Walker's slate quarry in 

 south-east Hanover, but in a different formation. 



From Meriden to Cornish Flat — four miles — we see the same rock in 

 abundance, with a south-easterly dip. Bean's, Colby's, Fifield's, Smith's, 

 and Jordan's hills, and French's ledge in Plainfield, are all of this type of 

 structure. A northerly projection of the formation, to connect the Plain- 

 field area with that in North Hartland, would add Prospect and Home 

 hills to the list. On the first there is a considerable band of a grey dolo- 

 mitic limestone, unlike the usual variety of this rock. I suppose it to be 

 the same with that analyzed by Jackson, giving, of siliceous matter, 25; 

 peroxide of iron, 2.8; carbonate of lime, 23.8; carbonate of magnesia, 

 46.6=98.2. We have traced it through Prospect hill, about three quar- 

 ters of a mile. It may extend to some of the localities mentioned by 

 Jackson south of the "Plain." This rock is unlike anything else in the 

 neighborhood, and we have had suggestions of its reference both to the 

 Huronian and to the Helderberg. It is on the line of the Huronian of 

 Willard's ledge. There is another outcrop of similar material south of 

 A. Bugbee's; and Mr. W. H. Daniels thinks its continuation may be 

 seen on the west slope of Black hill. The question of age cannot be 

 decided without further study. 



Mr. Huntington has carefully studied the rocks of Prospect hill, and 

 presents us with the following additional statement respecting them: 



"Just below D. Burnap's there is a synclinal in the hard, green schist, 

 with strike north and south. The limestone crosses the road fifteen or 

 twenty rods below Burnap's, and dips N. 50° W. 64°. Directly west a 

 quarter of a mile, the strike is nearly east and west; three fourths of the 

 way to A. D. Reed's the strike is nearly north and south. Above Bur- 

 nap's the green schist is strangely contorted. On the hill, a little west 

 of north from Burnap's, a whitish mica schist dips S. 80° E. 75°, but it 

 is bent very much in places. South-west of A. K. Reed's, a green schist 

 dips S. E. 72°. 



"The limestone north of Burnap's has a strike nearly north and south, 

 with westerly dip. There is no absolute proof that this limestone is Hel- 

 derberg. The surrounding rocks certainly are Huronian." 



Along the Connecticut river, the Calciferous ledges extend to Beaver 

 brook, the first seen there dipping easterly, and being quite argillaceous. 



