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Page:Popular Science Monthly Volume 72.djvu/512

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508
POPULAR SCIENCE MONTHLY

PSM V72 D512 Spring formed beginnings of a basin.png

The Tiny Rill of a Spring that has already developed a Small Basin.

of the Black Hand formation, which borders the floodplains of all the valleys, a distribution made possible because the formation has an eastern dip of about twenty-five feet per mile. The springs in the Black Hand are numerous and copious, partly because of the thickness

PSM V72 D512 Ample spring sources in coarse irregular sandstone.png

The Black Hand Formation is generally a coarse, irregularly bedded sandstone, yielding a copious supply of spring water.