406 STRATIGRAPHICAL GEOLOGY. 



tion of crystals of scapolite. The resultant rock rings like metal when 

 struck with a hammer. The width of the space between the two walls 

 of schist is two miles. The length of the rent, — that is, of the erupted 

 mass, — is five and one third miles. The direction is a little south of east. 

 It is very possible that a portion of t^e rock removed from this enormous 

 gap may have been absorbed or melted by the sienite; but most of the 

 opening must have originated from the forcible rending apart of the 

 strata. The edges of the schist next the sienite, wherever favorably 

 exposed for observation, show enormous granitic veins of a fine-grained 

 variety branching out from the larger mass of sienite. One is reminded 

 of the corresponding phenomena described upon Mt. Webster (p. 175). 

 It is interesting to know that these branching veins are usually finer 

 grained than the masses from which they proceed. 



In a small valley on the north-west side of the mountain, opening tow- 

 ards Brownsville, the limestones dip 75° S. 80° E., and abut vertically 

 against the sienite. Similar facts were observed in a valley on the south- 

 west side, the dip of the strata being 44° N. 50° E. In the precipice 

 here may be seen a granite vein sixty feet high and ten rods wide. In 

 another valley farther east the limestone and granite join each other 

 along a vertical line. 



Along the path up the north-east side we find the indurated calcareous 

 slate, about five hundred feet above the place of leaving the carriage-road, 

 dipping 40° E. The texture of the sienite up this path is usually some- 

 what coarse, the crystalline debris resembling gravel. The masses are not 

 so coarse, however, as those of the Conway granite in the White Moun- 

 tain district. On the very summit the hornblende is scanty, quartz is 

 wanting, and the rock is mostly a fine-grained crystalline felsite. The 

 rock of the mountain almost always carries some mica, so that hand 

 specimens may be procured of genuine granite. Of other granitic rocks 

 in our field of labor, the Chocorua aggregate is the most like that of As- 

 cutney. The conglomerate of the smaller mountain might be compared 

 with the Franconia breccia. 



Our final conclusion from the above facts, respecting the age of the 

 mountain, is, that there must have been an Eozoic foundation for it be- 

 fore the production of the limestones, a hill branching off from the great 

 gneissic range to the west. Subsequently the Calciferous mica schist 



