HEAD WATERS OF THE ANDROSCOGGIN. 36 1 



and may possibl}'' belong to a different series of rocks. Tlie hill immediately north of 

 Cupsuptic lake is a light gray argillitic schist. The strata are nearly everywhere verti- 

 cal, and the strike is N. 40° E. Northward along the river there is no outcrop of rocks 

 for several miles ; but at the falls of the Cupsuptic a rock similar to the last is found. 

 It differs from it in being of a darker color, somewhat more siliceous, and weathering 

 with a pitted surface near where it comes in contact with an intrusive granite. Having 

 seen a similar change elsewhere in the same kind of rock, under the same circum- 

 stances, it is more than probable that the granite was in some measure the cause of 

 the change. 



Sandstone Schist. Three miles north of Kennebago lake, on the Kennebago river, 

 we find a sandstone schist. Although it often resembles a mica schist, yet nearly every- 

 where there is no doubt as to the character of the rock ; and in some localities the frag- 

 ments of which it is composed are a quarter of an inch in diameter, and very distinct, 

 especially on the weathered surface of the rock. Elsewhere it has been greatly changed ; 

 and in some localities we find crystals of feldspar that have been produced since the 

 sedimentation of the rock. This sandstone extends northerly some eight miles along 

 the Kennebago river. On the mountain ridge north of Kennebago lake, where the 

 sandstone first appears, the strata are nearly vertical, and the strike is N. 70° E. ; but 

 along the river the strike is more northerly. South of this great area of rock we have 

 red and light gray argillites, and on the north we have diorite with serpentine. This 

 sandstone schist is the rock on the boundary at the head waters of the Cupsuptic 

 river, and it extends at least three miles southward along that stream ; and the same 

 rock outcrops on the Magalloway at Little Boys' falls north of Parmachena lake,— so 

 that the area of this rock is exceedingly irregular in outline. 



North-west of Kennebago lake, and extending south below the falls on the Kenne- 

 bago river, there is an area of light gray, dark purple, and red argillites. The strata 

 are vertical where observations have been taken ; and there are sudden changes from 

 one variety to the other. These argillites are probably the finer sediments derived from 

 the great mass of material from which the sandstone schists were formed. 



Diabase and Diorite with Serpentine. Diabase occupies an area on the Kennebago 

 river. The most northern outcrop is about a mile from its mouth, and it extends a 

 mile and a half northward along the river, and eastward towards Quimby pond. It is 

 not altogether certain that this is a metamorphic rock. If only the southern outcrop 

 had been seen, and the rock had been studied only in the field, we could have reached 

 no other conclusion than that it was intrusive, yet other outcrops strongly indicate that 

 the rock is metamorphic. At the head of one of the north-west branches of the Ken- 

 nebago, which rises near the point where the boundary extends farthest southward, 

 there is a iine-grained greenish rock, which would probably be distinguished as mela- 

 phyre by the German geologists. The area is limited here ; but there are extensive out- 

 crops on the boundary of New Hampshire, the summit of Mt. Carmel being composed 

 of similar rock. The metamorphic diorite is one of the most interesting rocks found 

 in this section of Maine. It outcrops on the Kennebago about twelve miles north of 



