The explanation of "agricultural use" is probably correct in some instances, for frequently the mounds are made of earth gathered up around their base, and so not only would be of value in a wet season, but would afford a much greater depth of fertile soil for sustenance of plants. In some localities modern farmers find that on such mounds crops are much better than on the low spaces between them. On the other hand, a majority of the small mounds in the lower counties of southeastern Missouri are composed either of the hard, reddish, sandy clay which forms the subsoil of the land above overflow; or of the tough, waxy, black "gumbo" of the swampy or flat lowlands. In either case they are almost invariably sterile, so that in a cultivated field the position of a mound is easily determined even from a considerable distance by the feebler growth on its surface. Moreover, in many places, hundreds of them occurring within an area of a few square miles are built on clay lowlands where crawfish abound, within a few rods of sandy, well-drained ridges whose soil is never muddy more than a few hours after the hardest rain, and produces as fine corn and wheat as can be raised in any part of the State.
In short, no matter what suggestion has been offered as to their purpose or uses, objections to it can be brought and sustained. It is not improbable that, in the end, it will be found the difficulty lies in trying to place in a hard and fast category a variety of structures which are similar in appearance but which were intended for various uses. With more comprehensive study, it may be that a classification is possible which will interpret what is now obscure. Instead of uniformity, there was probably great diversity of motives, ideas, and beliefs which led to the building of these as well as of other mounds; and when the key is once obtained the explanation which will account for one may be very different from that which as clearly accounts for another.
A few of these mounds have been explored by the writer, but no discoveries were made upon which can be based a definite statement as to their probable purpose.
NEW MADRID COUNTY
On the farm of A.B. Hunter, 7 miles north of New Madrid, more than 60 of these mounds, irregularly placed, extend for half a mile along the west bank of St. John's Bayou, the extreme width of the group being about 200 yards. The largest mound, standing on the edge of the terrace, was 6 feet high and 75 feet across. On the original surface, over a small area at the central part, were decayed fragments of human bones; so this was probably erected as a tumulus. The others were much smaller; from a foot to 3 feet high, and 30 to 50 feet in diameter. Six of these, varying in size from the largest to the smallest, were thoroughly excavated within the original margin and down to the undisturbed earth beneath them. No artificial object was found in any of them except here and there a fragment of pottery or a small amount of ashes or a piece of charcoal, not intentionally deposited but gathered up and carried in with the earth in the course of construction. There were no distinct fire-beds or ash piles at the bottom, or in any part of the mound; nor were there any holes in which posts may have stood.
ST. FRANÇOIS COUNTY
Nearly 2 miles south of Farmington, on Quesnel's land, are about 30 very small, low mounds, none more than 18 inches high or 25 feet across. They are on the general level, some of them on a gentle slope, of the first upland above the St. François River and a mile from that stream at its nearest point.