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Show j LARGE SPRINGS IN THE UNITED STATES What are the largest springs in the United States, how much water lio they discharge, and what geologic ; conditions produce them are questions ques-tions which the Geological Survey, United States department of the In- terior, lias answered in a report by O. E. Meinzer, that has just been published as Water Supply Paper 557. A spring of the first magnitude, according ac-cording to the classification adopted by the Geological Survey, is one of those which discharges at least 100 cubic feet a second, or 65 million gallons gal-lons a day. This is enough water to supply a city of half a million inhabitants inhabi-tants and is in fact, about the quantity quanti-ty that is consumed in Washington, D. C. The report shows that there are about 65 springs in the United States which supply at least this amount am-ount of water, and that there are several sev-eral springs or groups of springs in the country each of which produce enough water to supply New York City. Of the 65 first-magnitude springs 3S issue from volcanic rocks, 24 from limestone, and 3 from sandstone. Of the 3S springs in volcanic rocks 16 are in" Oregon, 15 in Idaho and 7 in California, of the 24 limestone springs 11 are in Florida, 7 in Mssouri, 4 in Texas, and 1 each in Alabama and Arkansas; the 3 sandstone spmgs are ail in Montana. The volcanic rocks are chiefly basalt that was greatly jointed and broken at the time it solidified, but large springs also issue is-sue from obsidian and rhyolite and from fracmer.tal volcanic material. Limestone is so readily worn away by percolating ground water that it may be full of crevices, coverns, and natural na-tural tunnels. In many limestone regions re-gions surface streams are virtually absent, and nearly the entire drain-ace drain-ace system consists of natural tun-' nels that carry the water under- ground. The sandstone springs and a few of the other large springs is-1 sue from great fissures produced by faulting. As a rule the large springs yield water that is very clear, but a few of the limestone springs become muddy after heavy rains. In deep spring pools the clear water generally gener-ally has a beautiful delicate blue hue, and hence the name "Blue Springs" is applied to several of the large springs. The water in some of the spring pools is so transparent that objects at the bottom are distinctly visible, and fish can be seen swimming swim-ming about as if in mid-air. In the well-known Silver Spring, in Marion j county, Florida, glass bottom boats are used and the view through the sun ! lit waters of the deep spring basin, with its underwater vegetation and fish of many varieties, is described , as truly fascinating. J The hunge springs that issue from : the black lava walls of the canyon of 1 ' Snake River below Shoshone Falls, in Idaho, are very spectacular. In a . 40-mile stretch of the canyon below j the falls there are 11 springs of the first magnitude, the largest of which furnish about enough water to J supply New York City, and alto-1 gether the springs that discharge in-! to this canyon yield enough water j to supply all the cities in the United States of more than 100,000 inhabit-1 ants with 120 gallons a day for each inhabitant. Unfortunately, however, ' not even one large city can avail it- j self of this abundance of spring wa-1 ter, wheh is as pure as any bottled water sold for general use. Many of the springs issue 100 to 200 feet ' above the river, and their clear waters wa-ters dashing over the black rocks of the canyon walls, produce cataracts of striking beauty. The Thousand Springs, wheh discharge 864 cubic ft. a second, are now in part harnessed to produce power, but formerly they made a waterfall 2,000 feet long and 195 feet high. Snowbank Springs, which is a part of the Thousand Springs, dashed over the rough talus slope formnig a cataract of pure white against a background of intense black. The Niagara Springs, which issue from the canyon wall 125 feet above the river level, also form a spectacular cataract- |