Post 00788
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Still more interesting is the rich and wonderfully varied flora of the mountains. Going up the Sierra across the Yosemite Park to the Summit peaks, thirteen thousand feet high, you find as much variety in the vegetation as in the scenery. Change succeeds change with bewildering rapidity, for in a few days you pass through as many climates and floras, ranged one above another, as you would in walking along the lowlands to the Arctic Ocean.
And to the variety due to climate there is added that caused by the topographical features of the different regions. Again, the vegetation is profoundly varied by the peculiar distribution of the soil and moisture. Broad and deep moraines, ancient and well weathered, are spread over the lower regions, rough and comparatively recent and unweathered moraines over the middle and upper regions, alternating with bare ridges and domes and glacier-polished pavements, the highest in the icy recesses of the peaks, raw and shifting, some of them being still in process of formation, and of course scarcely planted as yet.
Besides these main soilbeds there are many others comparatively small, reformation of both glacial and weather soils, sifted, sorted out, and deposited by running water and the wind on gentle slopes and in all sorts of hollows, potholes, valleys, lake basins, etc.,—some in dry and breezy situations, others sheltered and kept moist by lakes, streams, and waftings of waterfall spray, making comfortable homes for plants widely varied. In general, glaciers give soil to high and low places almost alike, while water currents are dispensers of special blessings, constantly tending to make the ridges poorer and the valleys richer. Glaciers mingle all kinds of material together, mud particles and boulders fifty feet in diameter: water, whether in oozing currents or passionate torrents, discriminates both in the size and shape of the material it carries. Glacier mud is the finest meal ground for any use in the Park, and its transportation into lakes and as foundations for flowery garden meadows was the first work that the young rivers were called on to do. Bogs occur only in shallow alpine basins where the climate is cool enough for sphagnum, and where the surrounding topographical conditions are such that they are safe, even in the most copious rains and thaws, from the action of flood currents capable of carrying rough gravel and sand, but where the water supply is nevertheless constant. The mosses dying from year to year gradually give rise to those rich spongy peat-beds in which so many of our best alpine plants delight to dwell. The strong winds that occasionally sweep the high Sierra play a more important part in the distribution of special soil-beds than is at first sight recognized, carrying forward considerable quantities of sand gravel, flakes of mica, etc., and depositing them in fields and beds beautifully ruffled and embroidered and adapted to the wants of some of the hardiest and handsomest of the alpine shrubs and flowers. The more resisting of the smooth, solid, glacier-polished domes and ridges can hardly be said to have any soil at all, while others beginning to give way to the weather are thinly sprinkled with coarse angular gravel. Some of them are full of crystals, which as the surface of the rock is decomposed are set free, covering the summits and rolling down the sides in minute avalanches, giving rise to zones and beds of crystalline soil. In some instances the various crystals occur only here and there, sprinkled in the gray gravel like daisies in a sod; but in others half or more is made up of crystals, and the glow of the imbedded or loosely strewn gems and their colored gleams and glintings at different times of the day when the sun is shining might well exhilarate the flowers that grow among them, and console them for being so completely outshone.