In the space of one hundred and seventy-six years the Mississippi has

shortened itself two hundred and forty-two miles. Therefore ... in the Old

Silurian Period the Mississippi River was upward of one million three hundred

thousand miles long ... seven hundred and forty-two years from now the

Mississippi will be only a mile and three-quarters long. ... There is

something fascinating about science. One gets such wholesome returns of

conjecture out of such a trifling investment of fact.

-- Mark Twain