6 RESOURCES OF CALIFORNIA. 



formation. The point, however, as before stated, is by no 

 means a fixed one : thus, during the night it extends farther 

 downward than in daytime ; in cloudy weather, for the same 

 reason, its course is more prolonged than under a clear sky. 

 In the stream-beds themselves, however dry, water is gener- 

 ally found a short distance below the surface. 



" The descent of these streams in the rainy sea,son may be 

 either a gradual process in the progressive saturation of their 

 sandy beds, or, the saturation being accomplished by previous 

 showers, the irruption may be sudden. A fine example of this 

 sudden appearance was observed in the San Diego River, in 

 December, 1849 ; when, after a rainy night, by which its sandy 

 bed was completely saturated, the upper stream suddenly ap- 

 peared in the form of a foaming body of water^ moving onward 

 at the rate of a fast walk, curling round the river-bends, ab- 

 sorbing the pools, and soon filling its bed with a brimming, 

 swift current. An instance of the more gradual descent was 

 seen in the following season (December, 1850), when, from 

 the absence of local rain, its downward progress was slow and 

 interrupted." 



The only navigable stream south of San Francisco Bay is 

 the Salinas, and that but for small vessels, and near its mouth. 



North of San Francisco the main streams rising in the Coast 

 Mountains are the Russian, Eel, Elk, Mad, and Smith Rivers, 

 all permanent, but none navigable. 



§ 5. Coast Lakes. — The only large lake in the Coast district 

 is Clear Lake, which lies about eighty miles northward from 

 San Francisco. It is twenty miles long, and varies in breadth 

 from two to ten miles. Surrounded by a small valley of fer- 

 tile land, it lies in a deep basin bounded by high mountains, 

 with an outlet to the eastward, where its surplus waters are 

 carried off by Cache Creek to the Sacramento. The water of 

 Clear Lake is limpid; the vegetation on its banks abundant 

 and vigorous ; the scenery beautiful and romantic. In Ama- 

 dor valley, twenty-five miles eastward from San Francisco, 

 there is a small lake, covering a couple of hmidred acres. It 



