42 STRATIGRAPHICAL GEOLOGY, 



large per cent, of lime, while on the hill east we find the wrinkled schists. 

 On the road just below the county farm the rock is almost as fissile as 

 slate, and on it are drift strias which are remarkably distinct. On Piper 

 hill there is a broad band of compact schist, containing cavities filled 

 with a yellowish brown powder. The same rock southward outcrops on 

 Sargeant hill. Passing into the valley east, at the saw-mill on Bishop's 

 brook, we have a good exposure of the schist containing lime as an in- 

 crustation. On account of the fragile nature of the rock and the lime 

 incrustation, this schist everywhere readily decomposes. Although the 

 ledges are often near the surface, it is seldom that they are seen except 

 along the streams, and then frequently the harder portions are mingled 

 with those that are partially decomposed. This is particularly noticea- 

 ble in the vicinity of J. Poor's, but in many places elsewhere in Stew- 

 artstown it can be seen. North of J. Poor's we found in the fragments 

 of the schist the mineral ankerite, also galenite. On the farm of Mr. 

 A. Fletcher we found the ankerite in a ledge ; and possibly a few blasts 

 might develop galenite. As this calciferous rock so readily decom- 

 poses, it is constantly supplying the lime that is necessary to produce a 

 fertile soil ; hence, also, the scarcity of boulders in the towns where this 

 rock is found. A fine example of the wrinkled schist, interstratified with 

 the more compact varieties, can be seen near J. M. Kidder's, The east 

 part of Stewartstown, as well as Clarksville, is still covered by the pri- 

 meval forests ; yet there are probably very few places in any state that are 

 more inviting, on account of the fertility of the soil, than is this section 

 of New Hampshire. 



Colebrook, except a small area in the south-west corner of the town, 

 and a strip on the east side, is composed of the schist containing lime. 

 The high hills north-east from Colebrook village, and extending east 

 along the Mohawk, are characteristic of this group of rocks. On Beaver 

 brook, at the falls, we find siliceous limestone, which is found so abund- 

 ant in this group in Vermont. The argillaceous schists, with which the 

 calciferous strata are interstratified, extend south to Sims stream, and 

 east nearly to the road running north and south through East Columbia. 

 In the north-west corner of Columbia, fifty rods north-east from the Jude 

 Fairnam place, there is a gray and drab colored limestone, interstratified 

 with the schist, "the strata running north-east and south-west, and in- 



