1/8 STRATJGRAPHICAL GEOLOGY. 



way down a high chff presents a smoothed aspect, as if there had been a 

 shding of one rock over the other at their Hne of union. Near this place, 

 also, the breccia is better developed, attaining a thickness of twenty feet. 

 The lower two hundred feet above the railroad are obscured by a large 

 pile of debris. 



On reaching the lower part of the small saddle back of the Mt. Field 

 spur the slates dip 50° S. 8° W. On the very ridge they seem to stand 

 about 85° N. 82° W. All about this tract of several acres extent the 

 strata are much contorted in small corrugations, and I also observed 

 masses of the breccia. South-westerly, in climbing up through the more 

 recent growth of trees, there is a light-colored quartzite. Farther north 

 I found no slates, but came to loose pieces of Conway granite, which may 

 possibly have come from neighboring ledges. I suspect the white, moist 

 rocks, of precipitous character, seen north of Willey brook at about the 

 same elevation with Mt. Willard, may be of this character. Higher up, 

 a bare ledge proves to be of the spotted or Albany variety, with nu- 

 merous joints a few inches apart, dipping 75° S. 8° W. On top of the 

 north shoulder of Mt. Field are ledges of greenish porphyry, not very 

 extensive. The small cone constituting the very highest point of Mt. 

 Field is composed of this same spotted rock, with joints dipping about 

 four degrees easterly, besides others nearly vertical. Combining these 

 observations with those mentioned on page 144, it appears plain that this 

 Albany granite is continuous from the south side of Mt. Field along the 

 ridge nearly to the top of Mt. Tom ; and it probably occurs beneath the 

 slates on the west side of Mt. Tom continuously to the smaller mountains 

 north. 



A word as to the top of the north-east spur of Mt. Field. In the ascent 

 direct from the uppermost Beecher cascade, no rocks appear save the 

 spotted variety. The summit is double, and very prominent joints dip 

 75° westerly, nearly parallel with the slate on its west side, which we 

 have traced to this saddle from Mt, Willard. It is also clear that the 

 slates pass from this saddle down to Cascade brook above Beecher's 

 cascades, and thence northerly to Mt, Andalusite, where they cease as 

 abruptly as they started on Mt. Willey. I have previously noted the 

 character and position of these slates on the Mt. Tom region. 



The conclusion to be derived from these statements is obvious. This 



