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University of California. 



[Vol. 3. 



nearly flat for perhaps half a mile square, with a very gentle 

 slope to the west. This flat slope is surrounded on nearly all 

 sides by precipices which are, for the most part, the walls of 

 glacial cirques. Sheep Mountain (Plate 32 a), five miles south 

 of Mt. Whitney, shows the same kind of a flat topped summit; 

 but this merges by a simple curve into a westerly slope which is 

 very smooth and even as viewed from a distance, but is much 

 steeper than the summit of Mt. Whitney. Similar characters 

 obtain along the summit divide as far as Cirque Peak, and por- 

 tions of the flatter summits even slope easterly, at a slight angle, 

 to the brink of the precipices on that side. The same surface is 

 well displayed iu a view from Mt. Guyot toward Mt. Whitney 

 (see Plate 33 a). In general, however, the westerly slope of this 

 portion of the summit range in smoothly flowing, sometimes 

 undulating, curves from the flatter summits is its most charac- 

 teristic feature. This smooth surface, where not interrupted by 

 glacial cirques, descends to an altitude of about 11,500 feet, 

 where it meets a splendidly defined plateau to be described 

 shortly. It has thus a hypsometric range of about 3,000 feet. 

 In this range the flatter portions of the slope are not confined to 

 the highest summits. About half- way between the upper and 

 lower limits there is a flat and quite broad terrace* which is best 

 exemplified in the summit tract between Sheep Mountain and 

 Cirque Peak. (Plate 32 a). Remnants of such a surface as that 

 here described are observable in various parts of the region. It 

 is evidently a significant feature of the geomorphy of the Upper 

 Kern Basin. For convenience of reference it is here named the 

 Summit Upland, from the fact that its character is well typified 

 in the summit of the Sierra Nevada from Mt. Whitney to Cirque 

 Peak, and that in this part of the region more people will prob- 

 ably make its acquaintance than elsewhere. 



The Sub-summit Plateau. — To the west of Cirque Peak the 

 summit upland descends by insensible gradations to a well 

 defined plateau which is best preserved in the country to the 

 west and southwest of the Siberian Outpost. This plateau may 

 be conveniently designated the Sub-summit Plateau. It is best 



♦This term is used as one descriptive of the geomorphic form without implica- 

 tion as to the origin of such form. 



