SCENOGRAPHICAL GEOLOGY. 621 



ravines about the White Mountains, partly because of the presence of 

 snow there all through the summer. Its position, in reference to the 

 main topographical features of the mountains, may appear by referring 

 to Plate C, page 338, to the representation of the mountains, and the 

 general geological map in the atlas. It rises directly below the summit of 

 Mt. Washington, having been excavated out of the plateau much in the 

 manner of a gorge. The beginnings of the cleft may be seen in the 

 heliotype of Mt. Washington from the south-east, while the general 

 aspects of the whole ravine are presented in Fig. 86. The head is 

 nearly two hundred feet below the summit; and the descent from the 

 plateau is dangerous along the most feasible route, and impossible most 

 of the way. The innermost part of the ravine is semi-circular, the outer 

 cliff rising directly a thousand feet. After receiving the waters flowing 

 from Huntington's ravine into it from the north, the gorge becomes much 

 more open, and is hardly to be distinguished from ordinary mountain val- 

 leys. Two small tarns, — one known as Hermit lake, — rest high up the 

 valley; and above them innumerable rivulets trickle down the cliffs, 

 known as Raymond's cataract and the Thousand streams in several pub- 

 lished stereographs. The cliffs are composed of andalusite slates, dipping 

 at a moderate angle into the moiintain north-westerly. 



Tourists are fond of imagining this and the other deep ravines in the 

 state as the product of some tremendous earthquake throe. They are 

 more easily explained by the action of frost, gravity, and water-power. 

 With the elevation of the mountains, there will be naturally a few lines 

 of depression, which give origin to streams. In the colder seasons, the 

 water freezing in the seams of the rock will detach slabs and blocks of 

 stone. These, acted upon by streams, will eventually be changed to 

 gravel and sand, and be washed down the mountain, leaving fresh sur- 

 faces for the renewed winter freezing. In this way, little by little, the 

 work of excavation goes on, the deep, ragged ravines notching the moun- 

 tains where the formation happens to be slaty and permeated with 

 numerous joints. 



The snow-arch is the feature which visitors delight to examine. The 

 violent winter winds blow immense quantities of snow from the summit 

 into this ravine, accumulating, it is said, to the depth of hundreds of feet. 

 The enormity of the mass enables it to resist the genial influences of tb'C 



