Forests are for cover. They mask not only the naked rock, but the paths of deer and bear and bighorn. Under the spire-pointed ranks of conifers that look so black from above, verging to blueness, a world of furtive folk goes on. A world of birds is in its branches, squirrels nimble as sparrows, but scarcely anything of this is visible to the watcher on the heights. Rabbits playing on your lawn would be more noticeable in proportion than the seldom-seen bighorn leading his light-footed young from ledge to rocky ledge. The jealous trees cover the trails and obscure the passes. As you come up through them you observe the flat, soddy spaces of old lake basins, green as jewels, and the hanging meadows gay with cascades of flowers, the stream tangles, the new-made moraines bright with bindweed and sulphur-flower. But from the heights all this lovely detail is hidden by the overlapping tents of boughs. Here and there a stream leaps forth at the falls like a sword from a green scabbard, or higher up, may be traced as the silver wire on which are strung unrippled lakes as blue as cobalt. Great chains of such lakes lead down from the snow-line to the foothill borders, encroached upon by the silent ranks of trees. As they go down they show soddy borders, they tend to fill and to grow meadows where presently deep-rooting trees assume their stations. This is the strategic rule for the taking of a granite mountain. First the grinding ice and the disintegrating water; what the streams wash down collects in the glacier-ploughed basins. It makes lake borders by which the grass comes in--the small grass that is mightier than mountains, that eats them for its food. Lakes at the lower levels become meadows, then trees arrive; they overrun the soddy ground, the snow-manured moraines. The trees themselves take centuries to fruition. At a later stage men dispossess the forest and build cities, but this has not yet come to the Sierras. There is something indomitable in the will of the trees to spread and climb. In the floor of Yosemite and Hetch Hetchy there are hundred-year-old oaks of full form and generous growth, and on the slopes above them the same oaks and of almost the same age are so dwarfed by drouth and altitude that they are not knee-high to a man, but they keep the due proportions of their type. A white bark pine will climb where the weight of the winter drifts is so heavy that it is never able to lift its decumbent trunk from the ground, clinging like ivy to the wall in which it roots.