Pirsson and Rice — Geology of Tripyramid Mountain. 269 



Art. XXVI. — Contributions to the Geology of New Hamp- 

 shire, IV. Geology of Tripyramid Mountain ; by h.Y- 

 Pirsson and ¥m. North Rice.* 



Introductory. — Tripyramid Mountain is in the southern 

 part of the White Mountains in New Hampshire. The point 

 formed by the intersection of 44° N. and 71° 30' W. is about 

 two miles northwest of its northwest lower slope. It is entirely 

 within the township of Waterville and a little east of its cen- 

 ter. Surrounded by other mountains, Osceola, Kancamagns, 

 Passaconaway, Whiteface, Sandwich Dome and Tecumseh, 

 peaks which rise 3-6 miles distant, it is much concealed, and 

 there are not many places where it can be observed in its full 

 proportions from below. The retired character of its situation 

 is much enhanced by the wild and heavily wooded nature of 

 the region in which it stands, the only habitations in the upper 

 valley of Mad River, which drains the township, being a sum- 

 mer resort hotel .and a few scattered farm houses. The east- 

 ern slopes of the mountain are drained by headwater branches 

 of Swift River, whose upper basin is a similarly wild and 

 heavily forested region. Consequently its summit is not easily 

 accessible and is little visited by tourists, especially as the view 

 is largely circumscribed by the neighboring peaks and obscured 

 by the thick growth of spruce scrub covering it. The best 

 point to reach it from is the hotel at "Waterville, which is 12 

 miles from the railway at Campton. A walk of about four 

 miles, partly on trails through the forest and partly a scramble 

 up rough and overgrown mountain brook beds, brings one to 

 the lower slopes and the slides described beyond. 



Topography. — Tripyramid Mountain is a roughly oval mass 

 which rises about 2000 feet above the floors of the valleys 

 about it. It is crested by three peaks with saddles between, 

 called the North, Mid, and South Pyramids, to which it owes 

 its name. Its appearance from the west is seen in the 

 accompanying view, which we owe to the kindness of Mr. 

 A. L. Goodrich. It was taken looking across the mead- 

 ows above the old lumber dam at a place on Slide Brook 

 called Swazeytown, below the junction with it of Cascade 

 Brook. 



On the north the mountain is connected with the peaks of 

 Kancamagns by a high ridge with an intervening point upon 



*Some years since one of us (L. V. P.) went to Waterville, N. H., to see 

 the occurrence of the " ossipite " mentioned in this paper and to collect 

 material. While engaged in this he found W. N. E. had also studied the Tri- 

 pyramid rocks in the field. We joined forces and the present paper is the 

 result. It is proposed to follow this with one dealing with the petrology of 

 the rocks. 



