d; at which height a perfectly level line extends through the whole
forest, marking the rise of the waters during the last flood.[363]

But most probably the causes above assigned for the recent origin of
these lakes are not the only ones. Subterranean movements have altered,
so lately as the years 1811-12, the relative levels of various parts of
the basin of the Mississippi, situated 300 miles northeast of Lake
Bistineau. In those years the great valley, from the mouth of the Ohio
to that of the St. Francis, including a tract 300 miles in length, and
exceeding in area the whole basin of the Thames, was convulsed to such a
degree, as to create new islands in the river, and lakes in the alluvial
plain. Some of these were on the left or east bank of the Mississippi,
and were twenty miles in extent; as, for example, those named Reelfoot
and Obion in Tennessee, formed in the channels or valleys of small
streams bearing the same names.[364]

But the largest area affected by the great convulsion lies eight or ten
miles to the westward of the Mississippi, and inland from the town of
New Madrid, in Missouri. It is called "the sunk country," and is said
to extend along the course of the White Water and its tributaries, for
a distance of between seventy and eighty miles north and south, and
thirty miles or more east and west. Throughout this area, innumerable
submerged trees, some standing leafless, others prostrate, are seen; and
so great is the extent of lake and marsh, that an active trade in the
skins of muskrats, mink, otters, and other wild animals, is now carried
on there. In March, 1846, I skirted the borders of the "sunk country"
nearest to New Madrid, passing along the Bayou St. John and Little
Prairie, where dead trees of various kinds, some erect in the water,
others fallen, and strewed in dense masses over the bottom, in the
shallows, and near the shore, were conspicuous. I also beheld countless
rents in the adjoining dry alluvial plains, caused by the movements of
the soil in 1811-12, and still open, though the rains, frost, and river
inundations, have greatly diminished their original depth. I observed,
moreover, numerous circular cavities, called "sunk holes," from ten to
thirty yards wide, and twenty feet or more in depth, which interrupt the
general level of the plain. These were formed by the spouting out of
large quantities of sand and mud during the earthquakes.[365]

That the prevailing changes of level in