26 GLACIAL AXD SURFACE GEOLOGY OF THE PACIFIC COAST. 



fall of rain, the quantity of which may in some rare instances be quite large. 

 Such events are not common enough to be allowed any weight as elements 

 in the climate. In the central portion of California snow only rarely falls in 

 localities lower than 2,000 or 2,500 feet above the sea-level. There are some- 

 times several years in succession when the portions of the Coast Ranges in 

 sight from the city of San Francisco, and from 3,000 to 4,000 feet in altitude, 

 are never whitened with snow ; and when this does occur, it is rarely for 

 more than a few days at a time. Yet there have been years when quite 

 heavy falls of snow have taken place, even in the valleys, in the immediate 

 vicinity of that city. 



In the Sierra Nevada, although the different years are quite variable with 

 respect to the snow-fidl, it does not often happen that it is not large in the 

 higher portions of the range. In some seasons it becomes enormous, amount- 

 ing, as is stated on good authority, to more than sixty feet. Of course, even 

 in ordinary years, the accumulations of snow in the deep canons, and in other 

 sheltered places into which it is driven by the wind, are sometimes of great 

 thickness. As a general thing this snow disappears very quietly, in large 

 jDart by evaporation, and the rivers are not so much swollen by its melting 

 as would be expected. It is only when a heavy general snow-fall is suc- 

 ceeded by a warm rain, occurring over a wide area and extending to con- 

 siderable altitude, that such heavy freshets take place as that of the winter 

 of 1861-62, when a considei'able portion of the Sacramento Valley was 

 deeply flooded with water. During ordinary years the snow appears, as the 

 range is seen from a distance, to have pretty much disappeared by May or 

 June. But the crest of the Sierra is never entirely denuded of its snowy 

 covering, although at the end of a long and hot summer, following an un- 

 usually dry winter, it may seem to be so. In the sheltered nooks and deep 

 crevices, especially on the north side of the higher peaks, patches of consider- 

 able size will always be found. This is especially true for the higher portion 

 of the range, as far north as the north end of Lake Talioe. Beyond this, to 

 Lassen's Peak, where the highest passes are not much over 7,000 feet, and 

 the peaks between 8,000 and 0,000 in height, there is ordinarily but very little 

 snow left at the end of the summer. In Plumas County there were in 1866 

 only one or two of the highest points on which snow remained through the 

 entire summer, all having disappeared except a few small patches on the 

 northern slopes of the most elevated peaks. On Lassen's Peak, however, 

 quite large bodies remain permanently ; or at least have always been there 



