GEOLOGY OF THE MERRIMACK DISTRICT. 503 



range has its northern hmit at the northern extremity of Beech hill, 

 where it has a dip almost directly north ; but on the same hill south 

 the dip is north-west. The rock seems more allied to hydro-mica schist 

 than to the common mica schist, and it contains compact fibrolite. 

 It is the rock directly east of Monadnock lake, and it occupies an area 

 of country here at least two and a half miles in width. It is the 

 rock of the country directly south of Dublin village nearly to Thorndike 

 pond, and south-west it is connected with the ridge of Monadnock. There 

 is an outcrop just south-east of the eastern extremity of Monadnock, and 

 on the road still farther south the rock is more decidedly a hydro-mica 

 schist than that found elsewhere in this range. Following the ridge of 

 Monadnock, the rock is quite uniform until we get near the highest point 

 of the mountain, when it becomes more compact, has fewer cleavage 

 planes, and contains some chlorite. The fibrolite, though generally pres- 

 ent, is not so abundant as on Beech hill, and it is the variety that was 

 formerly called bucholzite. On the north side of Monadnock, probably a 

 hundred and twenty rods a Httle east of north from the hotel, considerable 

 quantities of graphite were formerly obtained, but the mine is now nearly 

 or quite exhausted. The fact that graphite occurs here, would ally the 

 rocks of Monadnock with the older rather than the newer rocks. On the 

 north-west side of the mountain, and not far from a mile south-east of L. 

 Darling's, the rock resembles the micaceous gneiss of the White Moun- 

 tains, and it contains an abundance of the fibrous variety of fibrolite. The 

 rock on the ridge extending southward from the summit of Monadnock 

 is very similar to that on the ridge northward, and it crosses the road 

 just west of the toll-gate, where it is a very narrow band, and nearly 

 vertical. Southward, on Gap mountain, we have the andalusite schist 

 associated with a rock probably intrusive, and also with a dark gneiss. 

 The schist that outcrops in Fitzwilliam, west of S. Drury's, has a large 

 proportion of andalusite, and where it was examined had no other rock 

 with it ; that south of R. Fairbanks's has a fine-grained granitic gneiss ; 

 on the east and adjacent to it, that near G. Richardson's has the strata 

 vertical, and with it is a dark gneiss, similar to that on Gap mountain, 

 and it is probably the same kind of rock as that quarried near the station. 



