I20 STRATIGRAPIIICAL GEOLOGY. 



is full of andalusite, and dips 60° S. 62° W. At the first tank (from 

 below) a number of loose pieces of a mica schist, holding delicate crystals 

 of staurolite, are abundant, and they were at first supposed to represent 

 the ledge, but nothing of the kind has yet been discovered in place. 

 At the station the strata are mica schist, granitic layers, and andalu- 

 site beds, dipping 60° to 70° N. 38° W. This is the last ledge of the 

 schists observed in this neighborhood, though the granites which suc- 

 ceed seem to have been erupted through crevices in them. 



It should be distinctly understood that Nos. 10, 13-36 are regarded as 

 belonging to a much newer system than the Montalban, though they are 

 described above without special limitation. 



jE//is river above Pinkhain notch. After leaving the granitic gneisses 

 cropping out south of the Glen house, and we begin to ascend the valley 

 of Ellis river from the height of land in the road, we find a compound of 

 quartz and feldspar, granitic in appearance. Next we come to the Crystal 

 falls, where the base formation is a fine-grained variety of the Montalban 

 schists, traversed by enormous dykes of trappean character. The dip is 

 6Z° westerly. Half a mile higher the coarser mica schists crop out, with 

 an easterly dip. Ledges are scarce, however, in this valley ; and in Tuck- 

 erman's ravine the inclination is westerly again. The dip is very steep 

 low down, but only 28° above the snow-bank. High up the side of the 

 ravine, towards the summit of the mountain, the dip is in the direction 

 of N. 83° W. The ledges are finely developed near the snow-arch ; and 

 the westerly dip into the mountain may be distinctly apprehended in the 

 photographs of the "Thousand streams," and also in "Raymond's cata- 

 ract," on the easterly-flowing stream in the next ravine to the north. Dr. 

 J. W. Dawson speaks of the "gneiss" he observed in the depths of Tuck- 

 crman's ravine, in his paper on Alpine plants. The absence of the newer 

 series of rocks is as marked along the Ellis as in the west branch of the 

 Peabody river. 



SoittJi of Mi. WasJniigton. Trips to the south of Mt. Washington, in 

 several directions, afford a few observations. Upon the Davis bridle-path 

 the rock is uniformly the coarser feldspathic mica schist, with occasional 

 small, clearly-cut crystals of staurolite, in addition to the usual sparse 

 sprinkling of andalusite. On the cast side of Oakcs's gulf, before the 

 path descends much, the dip is from i4°-20° N. 43° W. Four and a 



