No. 7. J G. M. DAWSON — SURFACE GEOLOGY. 391 



broken flat or plateau, with a height, according to the barometer, 

 of 760 feet is reached. Through this little rocky hills project, 

 and its general elevation is probably nearly that of the body of 

 water which must formerly have filled the central " Gulf of Cali- 

 fornia" for a prolonged period. The road continues to follow 

 the Sacramento Valley in a general way for some distance, cross- 

 ing first a considerable tributary, and then re-crossing the main 

 stream. The upper part of the river is very tortuous, and flows 

 in a deep, steep-sided valley, up which, as the road gains a con- 

 siderable elevation, distant views of the snow-clad cone of Mount 

 Shasta are, from time to time, obtained. 



Leaving the Sacramento where it turns westward, we climb, 

 by a small lateral valley, to the summit of a plateau with an 

 elevation of about 2,300 feet, and at Strawberry Valley find our- 

 selves apparently close to the base of Shasta. A little further on 

 volcanic rocks are seen near the road, piled together in a way 

 suggesting the action of a glacier. Dr. Packard, who stayed 

 here to accomplish the ascent of the mountain, describes three 

 small glaciers which still remain near its summit, the upper four 

 thousand feet of which is covered with snow. These glaciers are 

 still engaged in piling up moraines, and have left others evi- 

 dencing their former extension. This mountain, at one time, 

 must have been an important centre of local glaciation, though 

 the phenomena of its vicinity are apparently quite distinct from 

 those of the almost universally glaciated north. 



Shasta reaches an elevation, according to Prof. Whitney, of 

 4,442 feet, and, in its grand isolation, and the remarkable sym- 

 metry of its conical form, is very impressive. 



Leaving Shasta, the road gradually descends into the broad 

 valley of a tributary of the Klamath River, and passing through 

 a wide gap in a range of hills, Yreka — once an important centre 

 of alluvial gold mining — is reached. About fourteen miles from 

 Yreka, a flat resembling a terrace was observed skirting one of 

 the hills, with an estimated elevation of 250 feet above the flat- 

 bottomed valley, or about 2,775 feet above the sea. 



Beyond Yreka the Klamath River is crossed, and on the line 

 between California and Oregon the Siskiyou Range is slowly 

 ascended, the summit on the road being, by my aneroid, 4,500 

 feet in height, and the actual descent from this place to the 

 stage stable on its western base being nearly 3,000 feet. 



After passing Jacksonville, situated on a branch of the Rogue 



