GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 



317 



quartzite reappears, carrying staiirolite. The dip is 65° westerly. The 

 actual junction of the quartzite and gneiss may be seen on the Ammo- 

 noosuc, near where the railroad has cut a passage 

 through a ledge of gneiss. Certain layers here and 

 in the village of Littleton are properly micaceous 

 quartzites, of a type that is characteristic of the Coos 

 group in Stewartstown, Vershire and Thetford, Vt., 

 and at various other localities. In the river, near 

 the Littleton depot, the dip is 80° northerly. On 

 Eustis hill it is 57° N. 27° W. This formation is 

 the same with that coming from Whitefield, east of 

 the Boston, Concord & Montreal Railroad, on Kim- 

 ball hill, and extending nearly to the Wing Road 

 junction. Both these ranges may once have been 

 united near Littleton, and crossed over the hill of 

 Bethlehem gneiss to join the Lisbon area about to 

 be described. 



The Kimball Hill range of these Cobs mica schists is rep- 

 resented upon Fig. 34, which is partly the same with Fig. 11, 

 PI. VIII. The latter figure shows the unconformable super- 

 position of the mica schists upon the Lake or Atlantic gneiss, 

 which is not separated here from the Bethlehem series. Some part of the valley be- 

 tween 2 and 3 is occupied by porphyritic gneiss. As the country is swampy and 

 wooded, it is difficult to trace the limits of the several formations within it. Farther 

 north there are patches of mica schist outcropping in it. 



The rocks of East Lisbon abound in staurolite, the ledges about Mink 

 pond having been long known to mineralogists. This area, the second of 

 our description, was separated from all other rocks in our first report, in 

 1869, under the designation of "staurolite schists;" and there is very 

 little change to be made from that representation of its topographical 

 distribution, save that the argillaceous division west of it is now incor- 

 porated with the grayish mica schists. The three leading varieties of 

 this formation in Lisbon are (i) quartzite, (2) staurolite mica schist, (3) 

 stauroliferous and garnetiferous clay slates. 



Of these the quartzites occur chiefly in a narrow strip colored as gneiss 

 on some of our maps, extending from the South Branch half way through 



