Post 00702
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It is a curious fact that the waters of some of the Sierra lakes and streams are invisible, or nearly so, under certain weather conditions. This is noticed by mountaineers, hunters, and prospectors, wide-awake, sharp-eyed observers, little likely to be fooled by fine whims. One of these mountain men, whom I had nursed while a broken leg was mending, always gratefully reported the wonders he found. One, returning from a trip on the head waters of the Tuolumne, he came running eagerly, crying: “Muir, I’ve found the queerest lake in the mountains! It’s high up where nothing grows; and when it isn’t shiny you can’t see it, and you walk right into it as if there was nothing there. The first you know of that lake you are in it, and get tripped up by the water, and hear the splash.” The waters of Illilouette Creek are nearly invisible in the autumn; so that, in following the channel, jumping from boulder to boulder after a shower, you will frequently drag your feet in the apparently surfaceless pools.
Excepting a few low, warm slopes, fountain snow usually covers all the Yosemite Park from November or December to May, most of it until June or July, while on the coolest parts of the north slopes of the mountains, at a height of eleven to thirteen thousand feet, it is perpetual. It seldom lies at a greater depth than two or three feet on the lower margin, ten feet over the middle forested region, or fifteen to twenty feet in the shadowy cañons and cirques among the peaks of the Summit, except where it is drifted, or piled in avalanche heaps at the foot of long converging slopes to form perennial fountains.
The first crop of snow crystals that whitens the mountains and refreshes the streams usually falls in September or October, in the midst of charming Indian summer weather, often while the goldenrods and gentians are in their prime; but these Indian summer snows, like some of the late ones that bury the June gardens, vanish in a day or two, and garden work goes on with accelerated speed. The grand winter storms that load the mountains with enduring fountain snow seldom set in before the end of November. The fertile clouds, descending, glide about and hover in brooding silence, as if thoughtfully examining the forests and streams with reference to the work before them; then small flakes or single crystals appear, glinting and swirling in zigzags and spirals; and soon the thronging feathery masses fill the sky and make darkness like night, hurrying wandering mountaineers to their winter quarters. The first fall is usually about two to four feet deep. Then, with intervals of bright weather, not very cold, storm succeeds storm, heaping snow on snow, until from thirty to fifty or sixty feet has fallen; but on account of heavy settling and compacting, and the waste from evaporation and melting, the depth in the middle region, as stated above, rarely exceeds ten feet. Evaporation never wholly ceases, even in the coldest weather, and the sunshine between storms melts the surface more or less. Waste from melting also goes on at the bottom from summer heat stored in the rocks, as is shown by the rise of the streams after the first general storm, and their steady sustained flow all winter.