Nevada, is a tract of high table land, about one hundred miles in length, surrounded on all sides by mountains, and called by Frémont the Upper Valley of the Sacramento. Here the growth of timber is vigorous and immense, for the climate and productions are modified by altitude as well as latitude. The Sacramento river, rising in the mountains at its northern extremity, reaches the Lower Valley through a gorge or cañon on the line of Shastl Peak, falling two thousand feet in twenty miles.
The Lower Valley is subdivided, as we have stated, into the valleys of the two great rivers, both of which are, at most, only a few hundred feet