THE KIVEB FLOODS 261 



basins of these rivers at a time when they con 

 tained a considerable quantity of snow. The rain 

 was so heavy and long-sustained that it was, of 

 itself, sufficient to make a good wild flood, while 

 the snow which the warm wind and rain melted on 

 the upper and middle regions of the basins was 

 sufficient to make another flood equal to that of 

 the rain. Now these two distinct harvests of flood 

 waters were gathered simultaneously and poured 

 out on the plain in one magnificent avalanche. 

 The basins of the Yuba and Feather, like many 

 others of the Sierra, are admirably adapted to the 

 growth of floods of this kind. Their many tribu 

 taries radiate far and wide, comprehending ex 

 tensive areas, and the tributaries are steeply 

 inclined, while the trunks are comparatively level. 

 While the flood-storm was in progress the ther 

 mometer at Knoxville ranged between 44 and 50 ; 

 and when warm wind and warm rain fall simulta 

 neously on snow contained in basins like these, 

 both the rain and that portion of the snow which 

 the rain and wind melt are at first sponged up and 

 held back until the combined mass becomes sludge, 

 which at length, suddenly dissolving, slips and de 

 scends all together to the trunk channel; and 

 since the deeper the stream the faster it flows, the 

 flooded portion of the current above overtakes the 

 slower foot-hill portion below it, and all sweeping 

 forward together with a high, overcurling front, 

 debouches on the open plain with a violence and 

 suddenness that at first seem wholly unaccountable. 

 The destructiveness of the lower portion of this par 

 ticular flood was somewhat augmented by mining 



