GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. II5 



Messrs. Channing and Hale, assistants of Dr. Jackson, ascended Mt. 

 Jefferson from the north, and make the following statements respecting 

 the ledges encountered by them:* "We travelled up the bed of the 

 stream [Israel's river], and observed that the rocks exposed to view were 

 ledges of granite, becoming coarser as we proceeded, and containing 

 small plates of mica not more than an inch square. Loose masses of 

 hornstone or jasper were observed among the pebbles in the stream." 

 "No [large plates of] mica were found, but an abundance of fibrolite or 

 fibrous kyanite occurs on Mt. Jefferson and Mt. Washington." 



The following rocks were found in a trip from Mt. Jefferson summit 

 directly to Ammonoosuc station, following down the ridge north of that 

 on which the railway is located: First, the common White Mountain 

 mica schist ; second, the same, extending as low as to the upper limit of 

 trees; third, granitic, like the Concord variety, within the upper forest; 

 fourth, quite a number of ledges of the mica schist; fifth, jointed granite, 

 the third ledge above the station ; sixth. Concord granites ; seventh, a 

 mixture of the two kinds of rock at Ammonoosuc. Specimens illustrat- 

 ing these varieties are embraced in Nos. 191-200. 



Upon Jefferson and Adams there are occasional large veins of white 

 quartz, whose course can be traced among the fragments very clearly, on 

 account of the contrast in color between this and the prevaihng variety. 

 Upon Mt. Clay the strata are better defined than is generally apparent 

 upon these summits, the rock approaching an argillaceous schist. They 

 are usually nearly vertical, and much thrown about, as described upon 

 Mt. Madison. 



Peabody River valley. At Gorham the rock is a coarse, massive gran- 

 itic gneiss, dipping 65° N. 72° W. back of the old Alpine house. It 

 continues up the Peabody valley for two miles or more, passing into the 

 Concord variety. This occurs, interstratified with the mica schist, nearly 

 as far as Copp's house in Martin's Grant, dipping five degrees north-west- 

 erly. Very near by is a mica schist dipping 65° N. 72° W., which is more 

 like the normal position in this neighborhood. Mica schists and granitic 

 gneisses occur between Copp's and the Glen house, and the latter in- 

 crease in going towards the height of land southwardly. Upon the west 



* Final ReJ>ort , Geology of New Hatiipshire , by C. T. Jackson, p. 159. 



