54 GLACIAL AND SUEFACE GEOLOGY OF THE PACIFIC COAST. 



the summit of over two miles. Above that they were abundant, and they 

 were also seen high up on the elevated ridges south, which rise to an alti- 

 tude of nearly 12,000 feet above the sea-level. The spurs between the 

 branches of the Stanislaus, for a considerable distance below the summit, 

 exhibit indications of the former existence of masses of ice of great thickness. 

 Professor Brewer's notes give the following particulars in regard to these 

 occurrences, obtained in his examinations along the Sonora Pass road, in 

 1863 : "We camped at the lower crossing of the Stanislaus, about eighteen 

 miles west of the summit, and examhied the hills south. The sides of the 

 caiion rise abruptly to the height of 2,500 or 3,000 feet. Granite extends 

 to within perhaps 700 feet of the higiiest point reached, which was of 

 volcanic, rudely columnar. Higher mountains are on every side, mostly 

 of o-ranite, capped with lava. On the ridges. lying between the forks of 

 the Stanislaus, north of us, these were exceedingly grand, rising perhaps 

 3,500 feet above the river. Their tops were worn into fontastic forms ; one 

 was not unlike an immense castle crowning the bold mountain. The rock 

 of the spur or ridge reached was of porphj^ritic lava, rather soft. Perched 

 near the top were ten or twelve large granite boulders, wliich must have 

 been deposited by ice, since they could not possibly have been carried 

 there by water. They were of coarse texture, the feldspar crystals very 

 large, some angular, others rounded and weathered. One of these, perched 

 on a very sharp ridge, measured seventeen feet long, fourteen wide, and 

 twelve high ; the others were smaller. Another lava spur, a fourth of a mile 

 east, had its top strewn with similar boulders. These must have come from 

 the east, where at the distance of three or four miles there is gi-anite at 

 a greater elevation than that of these boulders, and they must have been 

 brouo"ht by o-laciers that flowed from the hitjher mountains down the canon 

 of the Stanislaus River. No glacial polishings were observed, but the rock 

 is not well calculated to preserve them." Nothing indicating the passage 

 of glaciers was observed farther down the Stanislaus Valley. The road 

 descended at a considerable height above the river, the bed of which was 

 examined by the writer, at a point near the Sugar Pine mining district, and 

 no signs of glaciation found. This, however, was at a level probably consid- 

 erably below the point to which the former glacier reached at the time of 

 its greatest extension. 



At a still lower level, namely, of about 2,200 feet, between Sonora and 

 Columbia, several square miles of the surface of the limestone rock have 



