220 STRATIGRAPIIICAL GEOLOGY. 



the way of the tributary stream flowing down between Mts. Franklin and 

 Pleasant, between Mts. Clinton and Jackson, and also by ascending from 

 the Saco. No path has yet been marked out for horses, but the road is 

 easy to find, by simply following a watercourse. It is about six miles 

 from the Saco, six from Mt. Washington summit, three from Mt. Pleasant, 

 and four from the Crawford house, following up the bridle-path to Mt. 

 Clinton, and thence passing down the stream to Mt. Washington river. 

 When the latter route is taken, the explorer must remember to walk up 

 stream as soon as he has reached the Mt. Washington river. 



Other Labrador Areas. 



The remaining localities of labradorite have not been much explored, 

 and are quite limited in extent. In passing from the south end of the 

 Lafayette range in Lincoln to the road near Walker's falls, I found an 

 exposure of this rock, which gave, when examined, results almost identi- 

 cal with the analysis of the labradorite from Mt. Washington river. Prof. 

 Blanpied found in it, silica, 52.01,; alumina, 26.60 ; iron oxyd, 4.20; lime, 

 13.30; soda, 3.50; potash, .65=100.26. The rock is a dark, compact 

 mass, not composed of different minerals, as at the other localities, but 

 has crystals of labradorite scattered through a dark paste of the same 

 material, with an occasional bit of quartz. As far as from the spur at 

 the north base of Mt. Lafayette, to where the range first falls off rapidly 

 towards Mt. Liberty, a distance of five miles, there is a narrow range of 

 dark, compact felsite, apparently resting almost horizontally upon the 

 Albany granite, never more than two or three hundred feet wide; and, 

 as the specimen analyzed did not differ greatly in appearance from the 

 great mass of the rock, I had supposed the whole mass consisted of lab- 

 radorite, in the report for 1871, page 17. Specimens from the summit of 

 Lafayette, obtained in 1875, are evidently not labradorite; but the rela- 

 tions of the rock, at the south end of the range, to the rest have not been 

 reexamined. Boulders of labradorite occur at one or two places on the 

 west flank of the Lafayette range, so that it is likely there will be found, 

 upon further examination, a considerable exposure of the Labrador sys- 

 tem. Still, it is an open question whether the dark, compact labradorite 

 felsite may not be igneous in origin, and be connected closely with the 

 orthoclase felsitcs, of which the greater part of the range consists. 



