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
