coos AND ESSEX DISTRICT. 



41 



of iron pyrites, the cubes being half an inch or more in diameter. A 

 remarkable locaHty is on the east branch of Indian stream, about nine 

 miles north-west of Connecticut lake. On the northern border of the 

 Colebrook Academy grant the rock is more fissile, and approaches nearer 

 to a common black slate than it does elsewhere, but it contains the cavi- 

 ties just described, everywhere disseminated through it. Two miles 

 north-west from the mouth of the west branch of Indian stream the 

 rock becomes more micaceous, and the thin, wrinkled laminae are wait- 

 ing, but, what is more important, the dip changes. It is possible, however, 

 that it is only a fault. Northward, in Quebec province, we find both 

 classes of rocks just mentioned, and both have the same dip. The line 

 where the dip changes runs through the east part of Newport. On the 

 branches of Indian stream, three and a half and four miles from the 

 boundary, gold has been found to some extent, but it will be alluded to 

 more fully when we describe the drift. The rock here is the same as 

 that at Ditton, where gold has been so successfully washed. The rocks 

 of this group, which we have thus far noticed, had to be studied for the 

 most part while we were traversing a dense forest ; but, going south, we 

 come to the settled portion of Pittsburg. At Mrs. Tabor's, on Indian 

 stream, just east of the house where a few years ago a hurricane swept 

 away the forest, there is a fine exposure of the wrinkled schist. On 

 Hall's stream, just above the line, there is another outcrop of the same 

 rock, and, being near the road, it is more accessible. This rock extends 

 south, and it is the principal rock in the settled portion of Clarksville. 

 The more compact is everywhere interstratified with that which is 

 wrinkled and corrugated. There is an extensive area of the compact 

 schist just east of the road through Clarksville, a mile south of the bridge 

 that crosses the Connecticut. After passing the height of land in Clarks- 

 ville, going south, the rock becomes more calcareous, and is identical with 

 the formation which, in the report of the Vermont geological survey, is 

 called Calciferous mica schist, but it lacks for the most part the siliceous 

 limestone, which is an accompaniment of that rock in Vermont, except in 

 two or three cases, which will be noticed. It differs from the rock north 

 along Indian stream in no respect lithologically, except in the greater 

 abundance of lime. Under the bridge that crosses the Connecticut at 

 West Stewartstown there is a siliceous limestone in which there is a 



VOL. II. 6 



