156 STRATIGRAPinCAL GEOLOGY. 



The rock of Mt. Osceola is to be referred to the lower division, except 

 the eastern spur, which is Albany granite. At the first crossing of the 

 west branch of Mad river by the mountain path, I have noted the pres- 

 ence of large blocks of porphyritic gneiss. These Vv'ill probably be found 

 in place there, and will explain partially why the lower granites should 

 exist at so great an altitude as the summit of this mountain. 



A reexamination of the specimens from the lower part of the Tripyra- 

 mid slide, or what has been noted upon pages 38 and 39 of Volume I, 

 satisfies me that the rock should be referred to the porphyritic gneiss 

 instead of the "trachytic" or Albany granite. Hence we may accept our 

 first impressions of its gneissic character, and believe it to be simply an 

 extension of the rock on Cascade brook, perhaps including the cascades. 

 It may appear, also, that these ledges will connect with the loose blocks 

 beneath Osceola. I hope to reexamine the locality, and to present the 

 results of the visit in the sequel. 



On the ridge between Mad and Swift rivers, up Flume brook, the 

 granite uniformly has a fine grain. According to our present informa- 

 tion, the great range from Osceola to the east branch of the Pemige- 

 wasset, including the Black mountain, south of the mouth of Hancock 

 Branch, is of the Albany variety. From Waterville across the notch 

 between Mts. Osceola and Tecumseh into the north part of Thornton, 

 and from thence to Pollard's house in Lincoln, along the v/est edge of 

 the granites, the Conway granite is developed, capped at Loon pond by 

 higher groups. These two varieties continue beyond the East Branch 

 in the same order, the western range passing into Franconia, and the 

 eastern continuing uninterruptedly beneath Mts. Flume, Liberty, Lin- 

 coln, and Lafayette, then passing east of the range, as the continuity is 

 interrupted by underlying gneisses, capping Haystack, till we are brought 

 to the base of the Twin mountains, or our starting-place in this descrip- 

 tion. There will be some further details concerning the central part of 

 the Pemigewasset district, over a very important line, in Section VHI. 

 The actual junction between the Conway granite and Montalban group 

 is apparent near T. C. Pollard's. The schists dip at a very high angle 

 westerly; the granite appears to underlie them, and there is a large 

 vein of it in the strata, evidently injected subsequently to their deposi- 

 tion and elevation. Mr. Huntington has recently found the same granite 



