Il8 STRATIGRAPIIICAL GEOLOGY. 



that, after a succession of them for forty, fifty, a hundred feet, or more 

 are noted, their lower side disappears by plunging vertically into the 

 mountain, and another series of curves, with the vertical or westward 

 dip, takes their place. There are few places in New Hampshire where 

 these curious phenomena of curves can be observed to better advantage 

 than along this carriage-road. 



At No. 30 the dip is 30° N. 12° E., vertical just below. At No. 31, 

 close by the third mile-post and an easterly-flowing stream, the average 

 dip is 35°-40° N. 27° E. The axes of the small curves here run N. 30° 

 W., or transversely across their dip, showing that the smaller curves 

 have been made since the determination of the position of the great 

 mass of the formation. On the upper side of the long bridge over the 

 stream at No. 32 the dip is 50° N. 12° E., and the eastern portion of the 

 ledge is turning very much southerly. In the next fifty feet of linear 

 distance there are three folds. Above them the dip is 80° S. 87° W. ; 

 thirty feet above the dip is 80° N. Zf E. ; thirty feet farther the dip is 

 50° S. 87° W. This continues for one hundred feet. Here is a vertical 

 plunge into the mountain, the strata dipping gently in an easterly direc- 

 tion just beyond. Near by the dip is 65° easterly. The last of these 

 ledges that is exposed is midway from the third mile-post to the Half- 

 way house, with the dip 80° S. 87° W. (No. 35). For about a third of a 

 mile the road passes over drift, and no exposures of ledges occur imme- 

 diately along the path. 



This building is very near the upper limit of trees; and atmospheric 

 agencies have acted powerfully upon the ledges, weathering them very 

 much, so that they resemble the Montalban schists upon the surface. 

 Excavations near the house show massive beds of mica schist dipping 

 50° N. 23° W. At the fourth mile-post, or the most northerly point on 

 the road, and looking across a deep gulf to the south spur from Mt. Mad- 

 ison, the dip is N. 63° W. (No. 37). At a sharp turn beyond (No. 38) the 

 dip is 25° N. 23° W. At No. 39 the dips are 60° easterly and perpen- 

 dicular. At four and a half miles from the toll-gate the average dip is 

 60° easterly. At No. 40 there is an interesting complexity of folding. 

 The normal dip of the strata is S. 23° E., followed by a dip in the direc- 

 tion 25° N. 23° W., the other part of a synclinal axis. The southern part 

 of this synclinal basin, or that inclined northerly, is itself folded, the 



