Il6 STRATIGRAPIIICAL GEOLOGY. 



branch of the Peabody river, one of the most important gulfs on this 

 range, the rocks are mainly mica schists (Nos. 201-205), ?igreeing closely 

 with those found upon the presidential summits, and they all dip west- 

 erly, except one easterly, opposite the Half-way house. A ledge at the 

 mouth of this tributary is considerably ferruginous, with shining mica, 

 not in plates, nearly vertical. It is noticeable that none of the newer 

 andalusite slate, such as occurs so abundantly upon the lower half of the 

 carriage-road, was perceived in this great gulf, though there may be a 

 little of it at the mouth of the valley. The ledges near the Glen house, 

 and also by J. Bellows's, have the dip of 30° N. 58° W. 



Section tJirongJi Lit. Washington. This is properly a part of Section 

 IX, and the numbers referred to are those of specimens arranged on 

 Shelf IX in the museum. Special surveys of the Fabyan turnpike and 

 carriage-road having been made under our direction, I have had them 

 reduced so as to be represented upon Plate VII, with all the detail pos- 

 sible respecting the stratigraphical and geographical position of the speci- 

 mens collected. The positions of the mile-posts on the carriage road are 

 given with great exactness. Those of the specimens taken from inter- 

 mediate points are located by estimate. 



Directly back of the toll-gate is a ledge of greenish, somewhat friable 

 quartzite (No. 10). This and related ledges higher up dip 30° to 40° N. 

 83° W. At about three fourths of a mile there is a face of gneissic rock 

 exposed, 200 feet long and 40 feet wide, upon which glacial striae are 

 obscurely indicated. The mica in No. 1 1 is different in physical aspect 

 from that common to this region. The scales are narrow and much 

 elongated, instead of being roughly roundish. Interesting brecciated 

 dykes are represented by No. 12. These dykes are quite frequent on 

 their eastern slope, and are particularly noticeable at Crystal falls. At 

 the first mile-post the strata are also gneissic, with granitic veins dipping 

 30° N. 63° W. After passing about an eighth of a mile of drift there is 

 a massive quartzite. No. 13 is an argillo-mica schist, with undulating, 

 shining surface, and roundish, ferruginous spots of some decomposed 

 mineral. A small hill on the north-east side of the road is composed of 

 coarse granite (No. 14), containing large crystals of black tourmaline. It 

 is followed by ferruginous schist (No. 15) dipping 40° N. 23° W. Another 

 mass of granite is represented by No. 16. Between Nos. 14 and 15 there 



