and Texas.

In nearly every part of southern Missouri east of the Iron Mountain
Railway they occur in closely connected groups, reaching sometimes for
miles except where the continuity is broken by a slough or other
unfavorable condition. They are found everywhere--on high,
well-drained levels; on sloping ground, sometimes so steep that it may
well be called a hillside; in low "crawfish land"; in swamps where, in
the driest weather, even after a prolonged drought, they can be
reached only by wading through water or muck. The last, however, may
have been more easily accessible when built, their present condition
being due to the general subsidence of this region during the
earthquake period of 1811. The existing sloughs and sluggish bayous
are the widenings and extensions of streams which at the time these
mounds were constructed were no doubt bordered by banks above ordinary
overflow and readily reached by canoes. Manifestly the country was
well populated, and therefore presumably practically timberless;
consequently the flood water would rapidly pass away and the streams
not be choked by drift and other debris as is the case at present.

Various theories, most of them advanced by persons who are but
slightly, if at all, familiar with the country, have been propounded
to account for mounds of this character. Their vast number has led
some writers to believe that they can not be artificial but must be
due to natural phenomena; as, for instance, that these, as indeed all
mounds, were piled up by floods, Noachic, glacial, or local; or that
they result from the industry and energy of burrowing animals, such as
foxes, badgers, ground hogs, rabbits, prairie dogs, gophers,
chipmunks, or even ants; the character of the assumed flood or the
species of the supposed burrower depending to some extent upon
locality, but principally upon the theorizer's insufficient knowledge
of animal industry or of the action of torrential waters. Others are
convinced they are formed by the piling up of earth around a bush,
clump of grass, stone, or other object acting as a nucleus about which
wind-borne material may accumulate--overlooking the fact that clay,
gravel, or gumbo soil can not be carried by wind, and that lighter
soil or sand will form elongated instead of circular masses. Another
supposition is that they are due to stream erosion; flood waters
washing away the soil between them and thus leaving the earth
composing the mound in its o