From Mark Twain's "Life on the Mississippi" (1884):

In the space of one hundred and seventy six years the Lower  Mississippi  has
shortened  itself  two  hundred and forty-two miles.  That is an average of a
trifle over a mile and a third per year.  Therefore, any calm person, who  is
not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a
million years ago next November, the Lower Mississippi  was  upwards  of  one
million  three  hundred  thousand  miles long, and stuck out over the Gulf of
Mexico like a fishing-pole.  And by the same token any person  can  see  that
seven hundred and forty-two years from now the Lower Mississippi will be only
a mile and three-quarters long, and Cairo [Illinois]  and  New  Orleans  will
have  joined their streets together and be plodding comfortably along under a
single mayor and a mutual board of aldermen.  There is something  fascinating
about  science.   One gets such wholesale returns of conjecture out of such a
trifling investment of fact.