GEOLOGY OF THE MERRIMACK DISTRICT. 587 



mountain have not been explored. Fig. 102 embodies the observations 

 taken from Plumbago point across the summit to the Winslow house, and 

 so on to Wilmot Flat. I'he more elevated portion shows the presence of 

 two anticlinals and three synclinals, and the general attitude of the area is 

 synclinal, because it rests upon older rocks everywhere. 



Fig. 103 exhibits the stratigraphical structure of the mass in a section 

 through Andover, following the Northern Railroad. It would be possible 

 to recognize the same folds here as in Fig. 102, though they are closely 

 pressed together. The rocks rise again to the north in Ragged mountain, 

 and we ascend from Andover centre. Half a mile before reaching the 

 last house (G. W. Thompson's), andalusite schists dip 70° N. 70° W. The 

 lines of ascent and descent taken may be from a quarter to a half mile 

 apart. On the more western one, six hundred and fifty feet above the 

 house, the rock is vertical, and dips 80° N. 40° W. Eight hundred feet 

 higher than the house the dip is 85° N. 40° W. On the summit the 

 andalusite flags show numerous small convolutions, as on Kearsarge, the 

 average position being 75°-8o° N. 40° W. On looking south-westerly, 

 the strike of the ledges points towards Mt. Sunapee instead of Kearsarge. 

 Should this direction prevail, it would indicate the repetition of the Kear- 

 sarge strata upon Ragged mountain, separated by an axial line. This 

 mountain is just as much isolated as Kearsarge. The summit is in three 

 parts, the eastern peak being the highest of all, perhaps twenty-five feet 

 above the middle eminence supporting the signal of the Geodetic Con- 

 nection Survey. The strata on the eastern line of descent agree nearly 

 with those seen in ascending. Near Thompson's the strike is N. 30° E. 



The Ragged mountain ridge has been crossed between East Andover 

 and Hill. At the railroad curve, drift conceals the ledges. At L. Brown's, 

 after beginning the ascent, the strata dip high to the north-west. At B. 

 Tucker's are a few ferruginous layers. On top of the ridge the strata dip 

 80° N. 70° W. On reaching the town line, hard andalusite sandstones 

 and feldspathic beds occur, dipping io°-20° N. 70° W. On the north 

 slope, east of the road, are numerous embossed ledges, probably of the 

 same character. The first rocks seen in Hill are not adjacent to these 

 andalusite beds, and they are Montalban ferruginous schists, dipping 

 south-east. Our observations on this eastern line indicate the existence 

 of a probable anticlinal, but information sufficient to establish the nature 



