HISTORY OF GEOLOGICAL SURVEY. 43 



MT. PEQUAWKET. 



The same granite which appears at the Flume, is found in the Green 

 Hills, and all along through Conway, at Kiarsarge village, and in the lower 

 part of the mountain itself. Above this the trachytic granite occurs upon 

 all sides most distinctly (the fourth had not then been explored). It is not 

 abundant on the south and east, but very characteristic. On the south, 

 it crops out on the hillside below the slate. About five hundred feet 

 above the south base of Pequawket, and in the old foot-path (that of 1840), 

 occurs a ledge of clay slate, directly above the granite. This formation 

 does not seem to extend far, as it is not found in either of the new paths 

 up the mountain, and a very short distance from its lower boundary we 

 pass beyond it and come upon the rock of which the upper two thousand 

 feet of Pequawket appears to consist, viz., an igneous felsite, full of peb- 

 bles. The greater portion of the included fragments are angular, slaty, 

 lying at all angles, and range in size from an inch to a foot in diameter ; 

 but the pebbles, many of them rounded, also occur very frequently, and 

 were all taken from the rock in place. The slate above referred to 

 runs N. 70 E., S. 70 W., and dips 50 to 80 N. W., being much 

 twisted on a small scale. It does not appear either in the old or new 

 roads, but in the path of 1840. Five hundred feet north and south and 

 one thousand feet east and west seem to include the whole exposure, 

 though further examination may detect it elsewhere. The upper part of 

 Pequawket shows two well marked systems of joints, which seem to 

 affect nearly the whole mountains. At the top, one set runs S. 60 W., 

 and dips about 80 N. W. ; the other set runs N. 55 W., and dips about 

 80 S. W. It will be observed that the first set agree almost exactly 

 with the strike and dip of the slate in the lower part of the mountain. 

 In many places on the upper part of the mountain the rock has a thin 

 bedded sort of structure parallel to the jointed planes ; but whether these 

 divisions indicate a real highly inclined bedding remains to be seen. 



The slate lying above the trachytic granite is, in this respect, like the 

 felsites of Pemigewasset, but, unlike them, has been much twisted, and 

 reposes on the top of the terrace, inclined at a high angle. No doubt 

 would be entertained respecting its very much later origin than the upper 

 two thousand feet of the mountain, except that the latter is partly com- 



