From Mark Twain’s The Body of the Nation, Harper’s 1863:
It is a remarkable river in this: that instead of widening toward its mouth,
it grows narrower; grows narrower and deeper. From the junction of the Ohio
to a point half way down to the sea, the width averages a mile in high water:
thence to the sea the width steadily diminishes, until, at the ‘Passes,’ above
the mouth, it is but little over half a mile. At the junction of the Ohio
the Mississippi’s depth is eighty-seven feet; the depth increases gradually,
reaching one hundred and twenty-nine just above the mouth.
The difference in rise and fall is also remarkable–not in the upper,
but in the lower river. The rise is tolerably uniform down to Natchez
(three hundred and sixty miles above the mouth)–about fifty feet.
But at Bayou La Fourche the river rises only twenty-four feet;
at New Orleans only fifteen, and just above the mouth only two
and one half.
An article in the New Orleans ‘Times-Democrat,’ based upon reports
of able engineers, states that the river annually empties four hundred
and six million tons of mud into the Gulf of Mexico–which brings to mind
Captain Marryat’s rude name for the Mississippi–‘the Great Sewer.’
This mud, solidified, would make a mass a mile square and two hundred
and forty-one feet high.
The mud deposit gradually extends the land–but only gradually;
it has extended it not quite a third of a mile in the two hundred
years which have elapsed since the river took its place in history.
The belief of the scientific people is, that the mouth used to be
at Baton Rouge, where the hills cease, and that the two hundred
miles of land between there and the Gulf was built by the river.
This gives us the age of that piece of country, without any
trouble at all–one hundred and twenty thousand years.
Yet it is much the youthfullest batch of country that lies
around there anywhere.
The Mississippi is remarkable in still another way–
its disposition to make prodigious jumps by cutting through narrow
necks of land, and thus straightening and shortening itself.
More than once it has shortened itself thirty miles at
a single jump! These cut-offs have had curious effects:
they have thrown several river towns out into the rural districts,
and built up sand bars and forests in front of them.
The town of Delta used to be three miles below Vicksburg:
a recent cutoff has radically changed the position, and Delta is now TWO
MILES ABOVE Vicksburg.