Many groves and thickets would undoubtedly have grown up on lake and avalanche beds, and many a fair flower and shrub would have found food and a dwelling-place in weathered nooks and crevices, but the Sierra as a whole would have been a bare, rocky desert.
[Illustration: VIEW IN THE MAIN PINE BELT OF THE SIERRA FOREST.] It appears, therefore, that the Sierra forests in general indicate the extent and positions of the ancient moraines as well as they do lines of climate.

For forests, properly speaking, cannot exist without soil; and, since the moraines have been deposited upon the solid rock, and only upon elected places, leaving a considerable portion of the old glacial surface bare, we find luxuriant forests of pine and fir abruptly terminated by scored and polished pavements on which not even a moss is growing, though soil alone is required to fit them for the growth of trees 200 feet in height.
THE NUT PINE (_Pinus Sabiniana_) The Nut Pine, the first conifer met in ascending the range from the west, grows only on the torrid foothills, seeming to delight in the most ardent sun-heat, like a palm; springing up here and there singly, or in scattered groups of five or six, among scrubby White Oaks and thickets of ceanothus and manzanita; its extreme upper limit being about 4000 feet above the sea, its lower about from 500 to 800 feet.
This tree is remarkable for its airy, widespread, tropical appearance, which suggests a region of palms, rather than cool, resiny pine woods.
No one would take it at first sight to be a conifer of any kind, it is so loose in habit and so widely branched, and its foliage is so thin and gray.

Full-grown specimens are from forty to fifty feet in height, and from two to three feet in diameter.

The trunk usually divides into three or four main branches, about fifteen and twenty feet from the ground, which, after bearing away from one another, shoot straight up and form separate summits; while the crooked subordinate branches aspire, and radiate, and droop in ornamental sprays.

The slender, grayish-green needles are from eight to twelve inches long, loosely tasseled, and inclined to droop in handsome curves, contrasting with the stiff, dark-colored trunk and branches in a very striking manner.