234 



icAi. (;koi.O(;y. 



siip:t;csts readily tlio stiiulurc of lliis formation. Tt is a crushed, nearly 

 inverted synclinal axis, overlyinj; the Monlalban system, perhaps uncon- 

 formably. Both systems are characterized by the i)resence of crystals of 

 andahisile. 'I'hese are usually uuich lar<^er in the newer than amonj; 

 the older strata, save where they have been altered into Damourite, as at 

 Willis's Seat. The Monlalban andalusite commonly occurs like chewed 

 l)ieces of toothpicks, si-allered indiscriminately throui;!! the ledges. 



The slates about Mt. ]'e(|uawket occur in two limited isolated localities, 

 one on tlie south side, and the other opposite, on the east branch of the 

 Saco, about a mile and a half above its mouth. The two are nearly in 

 their pi-oix-r place for a continuation of the ran.i;e southerly from the val- 

 ley of ICllis river. Tt may be that these two areas are continuous beneath 

 the granitic and brccciatcd cap of the mountain, although the strike of 

 the southern mass does not point towards the northern. The disturb- 

 ances which accompanied the formation of the breccia may have de- 

 ranged the course of the slate, so that its original direction is lost, or 

 there might be a bend in its course similar to that below Mt. Willard. 

 These localities are over two miles apart. The northern one is the larg- 

 est, extending easterly from the river. No andalusite has been noted in 

 these slate ledges; but the boulders derived from them in Conway dis- 

 play the silicate in jirofusion, so that the affinities of the formation arc 

 unmistakalile. It occurs to us now, that the "dark siliceous schists" of 

 Jackson, ilescril)cd upon i)age 130, may i)erhai)s be referred to this series. 

 If so, there would be opportunity afforded for showing further the truth 

 or error of the supposed connection between the different areas of anda- 

 lusite slate. 



Further reflection upon the character of these schists from Jackson 

 suggests their similarity to a supposed jxvrt of the Huron ian system 

 already described as occurring along the lli)])er Anunonoosuc region, 

 and also to be sjioken of hereafter in Rockingham county. The small 

 outlier cast of Berlin falls is of the same sort. At various times the pos- 

 sibility of an intimate connection between the Andalusite slates and the 

 Iluronian schists has been thought of. This suggestion will receive 

 speedy attention from us. By reference to the catalogue and the map 

 illustrating the distribution of specimens, it will appear that the quartz- 

 itcs and ferruginous schists, — Nos. 84, 129-132, 135-137, 142, 144, 146, 



