58 GLACIAL AND SUEFACE GEOLOGY OF THE PACIFIC COAST. 



Bear Eiver, on the other hand, being near the line of the Central Pacific 

 railroad, which runs on the divide between that stream and the North Fork 

 of the American, has been pretty thoroughly explored, and the evidences of 

 former glacial action traced down to a little below Emigrant Gap, 5,521 feet 

 above the sea. On the mountain immediately north of Summit Station, at 

 a point 7,722 feet above the sea, a glacially scratched and polished surface 

 was observed, indicating that the ice-mass was here not less than 700 feet 

 in thickness. From the summit down the valley old moraines may be seen 

 high above its bottom, along the top of which, or near it, the railroad occa- 

 sionally passes for some distance. At Sereno Lake, where ice is cut for the 

 supply of the railroad company, the moraine, there very distinctly marked, 

 was about 400 feet above Summit Valle}^ Near Emigrant Gap the road 

 is built on the southerly and southeasterly flank of an old moraine of great 

 size. The top of this is from one to three hundred feet above the line of 

 the track, the slope descending some 300 feet or more, and in places as 

 much as 500 feet, to the bottom of the nearest depression, called Wilson's 

 Ravine. The \ipper portion of the ridge is thickly dotted with granite 

 and lava boulders as far down as Sailor Ravine, about three miles by the 

 track below Emigrant Gap. Professor Pettee remarks in his notes of this 

 region as follows : " It was at the head of this ravine, a quarter of a mile 

 from the track, that I saw the last granite boulder on this trip. Later in the 

 season I started from Blue CaSon Station, and found a single piece of gran- 

 ite about half a mile farther down than Sailor Ravine, at a point nearly due 

 east from the Blue Canon Station, at an altitude of 5,081 feet. That is the 

 lowest point at which I saw evidences of the remnants of glacial action. 

 On the opposite side of Bear River, two miles to the northwest of the rail- 

 road line, there is a considerable moraine extending down to a probably 

 somewhat lower level than that just described. But there is no information 

 as to the precise point to which it descended." 



A large extent of country, somewhat lower down on the slope of the 

 Sierra than that which has already been noticed, was explored by Mr. 

 Goodyear, as detailed in the preceding pages.* His field of work lay 

 chiefly between the South Fork of the North Fork and the Middle Fork of 

 the Middle Fork of the American River ; at least, it was only in the part of 

 the Sierra between these two streams that he in the course of his explorations 



* For details of the route [mssed over by Mr. Goodyear in the course of his exploratious, see page 82, and 

 accompanying diagram, Plate B. in the gravel volume. 



