HISTORY OF GEOLOGICAL SURVEY. 35 



tains, besides the parts already specified. The mountains show a finer grained rock 

 than the valleys. Some of it seems to extend into the uncolored area between No. i 

 and the Lafayette range. This probably connects under Flume mountain with the 

 granites on the East Branch in Lincoln and Thornton. More appears near the forks 

 of the East Branch, Hancock mountain, and the ridge north, including the falls in 

 the valley of Mad river in Waterville, abundantly in the Swift River valley in Albany, 

 and about Conway, passing under Pequawket, and extending into the Green Hills. The 

 small area of Bald Face and Mt. Eastman in Chatham has a fine grain, and possible- 

 is of a different age. 



The largest area of this rock upon the map extends from Jackson to Carroll. The 

 Saco valley above Rocky Branch is mostly excavated out of it. The excavation of the 

 White Mountain notch out of this granite was alluded to last year. The high range north 

 from Mt. Lowell to Mt. Willard is probably of this rock. East of the Saco the andalu- 

 site gneiss seems to have been cut by it, Mts. Crawford and Resolution being composed 

 of granite. Mt. Deception, and the country east of the old Fabyan house, are made up 

 of a different sort of a granite, whitish or grayish in color, with the feldspar in narrow 

 crystals, porphyritic in appearance. But the range from the north end of Mt. Tom to 

 the lower falls on the Ammonoosuc, and the three "Sugar Loaves" farther west, are 

 entirely of the typical variety of coarse granite. 



6. Trachytic Granite. Above No. 5, with the same horizontal appearance, is a 

 granite of trachytic or semi-porphyritic aspect. The feldspar is orthoclase, as shown 

 by analysis, and most of the rock is made of it, being essentially rounded crystals 

 imbedded in a granitic paste, with scarcely any quartz, and rarely a peppering of dark 

 mica. It often contains a small per cent, of manganese. The first great expanse of this 

 rock lies between the saw-mill of Rounsevel & Coburn, in Carroll, on the Ammonoosuc, 

 and Waterville. The Twin Mountains, Haystack, a portion of the Lafayette range 

 beneath the cap, Mts. Liberty, Osceola, and other high peaks, are mainly composed of 

 this trachytic granite. It will be observed that this area is wholly in the forest region, 

 untraversed by roads ; hence it is not strange that its peculiar characters should not 

 have been recognized earlier. There is some of this rock north of Mt. Carrigain, and 

 the Sawyer's Rock range appears to belong here. Other localities are high up Rocky 

 Branch in Bartlett, Iron mountain, the valley of the Saco in Bartlett, underlying the 

 great mass of Pequawket, but above the common granite. The rock referred to this 

 division, along the Swift river and the Ossipee mountains, is made of finer materials, 

 with more of the paste, and that of a darker color than the ledges farther west. It 

 also disintegrates less readily. 



7. Brecciated Granite. This designation applies to the rocks forming Eagle cliff 

 in Franconia, and several nameless peaks between Profile and Kinsman. The frag- 

 ments most easily recognized are those of porphyritic gneiss, dark gneiss, and horn- 

 blende, imbedded in a very compact feldspathic paste. Along Eagle cliff there are 

 appearances of stratification, and at Echo lake the brecciated granite appears to 

 underlie the porphyritic gneiss. The rock is irregular in arrangement, as if thrust 



