Harold Fisk and the Mississippi River

Rivers meander over their course as they continuously erode and deposit sediment. Harold Fisk, a geologist and cartographer working for the US Army Corps of Engineers, mapped the meanders of the mighty Mississippi in 1944 and the results are mesmerizing. (See below) They also beautifully illustrate geology’s Law of Superposition: newer and younger sediments are deposited on top of older sediments. We see thousands of years of course changes. You can unravel the layers by eye by noting which layer cuts others.

Or you can cheat and use the map legend which has the youngest course on top, to the oldest on the bottom!

“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 one 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 River was upward of one million three hundred miles long, and stuck out over the Gulf of Mexico like a fishing-rod.

“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 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.”

~ Mark Twain, Life on the Mississippi, 1883

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