... diameter of six inches to the depth of 425 feet, and after that it is reduced to four inches. For about three thousand feet the strata penetrated were of carboniferous and magnesian limestone alternating with sandstone. The remainder of the well passes through igneous rock. At St. Louis the Missouri and Mississippi rivers are not more than twenty miles distant from each other, and it is worthy of note that the waters of neither of those two rivers appear to have opened for themselves a considerable subterranean passage through the rocky ... — The Earth as Modified by Human Action • George P. Marsh
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