Page:Popular Science Monthly Volume 35.djvu/883

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into midsummer, while at still greater altitudes, in sheltered places, it remains throughout the year. By its topographical structure the park is designed by nature as a reservoir for receiving, storing, and distributing an exceptional water-supply, unexcelled by any area near the head-waters of the great rivers. The continental divide, separating the waters of the Atlantic from those of the Pacific, crosses the plateau from southeast to northwest. On both sides of this divide lie several bodies of water, which form so marked a feature in the scenery of the plateau that the region has been designated the lake country of the park. Yellowstone Lake presents a superficial area of 139 square miles, and a shore-line of nearly 100 miles. The discharge at the outlet was found in September, 1886, to be 1,525 cubic feet per second, or about 35,000,000 imperial gallons per hour. Dr. William Hallock estimates, from measurements, that the amount of water running into the park and leaving it by the five main drainage channels would be equivalent to a stream five feet deep, one hundred and ninety feet wide, with a current of three miles per hour, and that over an area of four thousand square miles the minimum discharge was equal to one cubic foot per second per square mile. For the preservation and regulation of this water-supply, the forest, which covers the mountains, valleys, and table-lands, and everywhere borders upon the lake-shores, is of inestimable value. Of the present park area about eighty-four per cent is forest-clad, mostly with coniferous trees.


The Glacier of Mount Tacoma.—Relating, in the "School of Mines Quarterly," an excursion to the great glacier of Mount Tacoma, Mr. Baily "Willis describes the glacier, when the party came upon it from the bed of Carbon River, as rising, like a wall of ice, from thirty to fifty feet, across the path, while the river tumbled in little cascades from a low cave in the center. The upper surface of the wall, all its sharp ends having been melted off, was covered with a layer of rock and earth. "I think," says the author, "there can be no better illustration of the advance of a glacier to the point where the melting at its face balances the downward progress, than this worn, shrunken extremity, pressed on as it is by a vast accumulation of ice in the basin between Tacoma and Crescent Mountain. It pushes no great terminal moraine before it. It meets with no obstruction save the narrowness of the cañon; but here in the shadow of the cliffs the air-currents from the west bid it halt." The Crescent Mountain glacial system is fed by slopes which descend ten thousand feet in five miles from the Liberty Cap, Tacoma's northern summit. "Much too steep for snow to lie on, except on the highest shoulders where it packs to a depth of several hundred feet, the upper third of this tremendous height is bare black rock, on which the avalanches shatter into clouds of eddying smoke. The lower four miles are covered with a sheet of flashing ice, which pushes downward over the uneven surface, here carrying huge gleaming pinnacles aloft, there flowing in graceful curves like a river's current. Its western portion comes onward to the cliffs of Crescent Mountain, nearly three thousand feet high, and turning from them sweeps down into the gorge of Carbon River; the eastern part extends a long tongue into a meadow brilliant with flowers, whence White River plunges into its unexplored canon. This meadow is but one end of a green valley that nestles strangely in this region of perpetual frost and sterile rocks, bounded on three sides by ice and snow, and on the fourth by forbidding precipices."


Origin of New Forest Growths.—Observations on the "new growth" of trees that appears after forest fires have been described by Prof. W. J. Real, of the Michigan Forestry Commission. The stubs of most deciduous trees sprout after a fire, and are capable of preserving their vitality for a very long time. Slender oaks, resembling young sprouts, may be found in the forests attached to clumped roots of "grubs" of various sizes, that will show that the present growth is the first, second, third, or fourth sprout that has apparently come in succession from the same foundation. Of three little oaks which were found still having the remains of the seedling acorns attached by the stems of the cotyledons, one was five years old. Others, some four inches high and less than an eighth of an inch in diameter, were shown by the remains of the bud-rings to be from