





2 



THE ATJEIFEROUS GEAVELS OF THE SIEKRA NEVADA. 





students of the physical geography of North America, they must be here 

 indicated with some detail, since an understanding of the nature of the 

 Gravel deposits of the Sierra depends so much on an acquaintance with the 

 physical peculiarities of the region over which they are distributed. 



Let us assume as the central point of our picture of the topography of 

 California its most striking feature, "The Great Valley/' and from this let 

 us then extend our view first to the region 'immediately adjacent to it, — its 

 edge, so to speak, — and then to the more remote portions of the State, which 

 indeed have but little geographical or geological connection with it, or with 

 the subject of the present volume. 



The Great Valley — the valley of the Sacramento and San Joaquin rivers 

 forms an area of almost level land, having a roughly elliptical form, trend- 

 ing about N. 30° W. and S. 30° E., and embracing about 18,000 square miles. 

 It lies between latitudes 34° 50' near Fort Tejon, and 40° 40' near Shasta, 

 having an extreme length of 450 miles and an average width of forty. The 

 shape of the area of flat land, between the foot-hills of the mountains which 

 enclose it, is somewhat irregular. The base of the Sierra Nevada on its east 

 side has a pretty regular trend north of latitude 35° 30'; but south of this it 

 bends around towards the west, and thus, meeting the Coast Range* closes 

 up the southern end of the valley. The northern end is also closed by the 

 convergence of the Sierra and Coast Ranges, the latter chain assuming a 

 northerly trend from Clear Lake north, while that of the Sierra continues 

 the same beyond the limits of the valley. Above Red Bluff, indeed, the 

 ranges approach each other very nearly, the volcanic overflow from the 

 Sierra coming quite down to the Sacramento at this point ; while a little 

 farther north this river almost touches the foot-hills on the eastern side of 



* 



the valley, and is only a few miles distant from them on the west. A section 

 across the valley, in the direction of its length, shows that the fall of the 

 Sacramento River, from Redding to its mouth, a distance of 192 miles, is 

 556 feet; while that of the southern portion of the valley, between Kern 

 Lake and the mouth of the San Joaquin, a distance of 260 miles, is 282 feet. 

 The fall of the Sacramento River, within the limits of the Great Valley, is 

 therefore about three times as rapid as that of the river system which drains 

 the southern section. Indeed, the lower or most southeastern portion of 

 the Great Valley, usually called the Tulare Valley, is very nearly a level 

 plain, occupied in part by shallow lakes. Of these Tulare Lake is the largest, 

 having an area of 687 square miles and a depth of only about forty feet. 





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