212 



BULLETIN OF THE 



two and a half to seven inches in diameter. In respect to numborB, this 

 was an exceptional case, bvit single inclusions met the eye at every 

 turn. Of specimens collected in the basin, some have their outlines 

 sharply defined, but others merge gradually into the enclosing granite. 

 As usual, they are finer in grain, and of darker color, than the sur- 

 rounding rock, being commonly of a deep gray, but sometimes ligliter 

 from the presence of imbedded crystals of white feldspar. Upon the 

 Southwest and East Slides a few inclusions were found of another char- 

 acter. Of these, one was brought away from each locality, — the best 

 of its kind. They seem to be fragments of almost black mica schist, 

 arc angular on all sides, are separated from the granite by lines per- 

 fectly distinct, and were selected as pieces of foreign rock which had been 

 caught up by the granite and included within its mass. 



Inclusions in granite have long attracted attention, but have not 

 been the subject of much investigation. A clear and extended discus- 

 sion of their nature, with figures of specimens and a record of analyses, 

 may be found in a paper, by J. Arthur Phillips, entitled '' On Concre- 

 tionary Patches and Fragments of other Rocks contained in Granite." * 

 In his '^General Conclusions," the author makes tlie following state- 

 ment : ^'The inclusions contained in granite are of two distinct kinds. 

 Those of the first class [which are spoken of throughout the article as 

 concretionary, though not exiiibiting a concentric structvirc] are the re- 

 sult of an abnormal arrangement of tlie minerals constituting the granite 

 itself, while those belonging to the second represent fragments of other 

 rocks enclosed within its mass." (p. 19.) Most of the patches observed 

 in the basin must be assigned to the first class, while tl)e specimens 

 brought from the slides seem clearly to belong to the second. 



The forms which the several parts of the mountain now present, and 

 the condition of their surfaces, are largely due to the original structure 

 and mode of weathering that characterize the rocks. As the highly in- 

 clined concentric sheets in the basin walls break away, and fall upon 

 the talus below, other faccy of equal inclination are exposed ; while the 

 red granite of the higher parts, deprived of support, in turn gives way, 

 and thus the steepness of the walls is maintained. Similar steep faces, 

 due to the concentric structure of the granite, abound upon other parts 

 of the moimtain, as on the flanks of several spurs, and about the base 

 at various points. 



The crest (a feature unique among Eastern mountains) that occupies 

 most of the space between East Peak and the Chimney owes its form and 



* Qaar. Jour. Gool. Soc of London, Vol. XXXVI. pp. 1-22, February, 1880. 



