The works, consisting of a series of mounds and terraces, accompanied by lines of embankment and by excavations, are found near the south-western portion of the prairie, and partly in what is now woodland, though probably at no very remote date free from forests. The mounds are disposed with some degree of regularity in respect to each other, and are of the following dimensions:
| length, feet | width, feet | height, feet | |
|---|---|---|---|
| A. base, | 180 | 135 | 48 |
| A. summit, | 51 | 45 | |
| B. summit, | 210 | 75 | 5 |
| C. base, | 132 | 132 | 4 |
| D. summit, | 120 | 120 | 4 |
| E. summit, | 60 | 42 | 10 |
| on summit, | length, feet front | length, feet rear | length, feet wide | length, feet high |
|---|---|---|---|---|
| F. | 60 | 78 | 42 | 12 |
| G. | 60 | 39 | 51 | 12 |
| H. | 60 | 60 | 54 | 7 |
| I. | 36 | 27 | 45 | 10 |
The embankment between E and F is one hundred and thirty-five feet long, fifteen feet broad at the base, and four high. The embankment j k l is ten hundred and fifty feet long, twelve feet broad and from one to three feet high.
The great mound E has been denominated “the Temple.” It has a level area on its summit fifty-one feet long and forty-five broad, which is reached from the west by the winding graded path X. All its angles are much rounded; still its four faces are very plainly marked. Since it has been cleared of trees, several p114 slides have marred its symmetry. These slides, as also excavations made in it, have shown that it consists of a series of strata or tables, one above the other, each surmounted by a burned surface, resembling rude bricks. No bones have been found in it. Any extended examination of its contents is avoided, from a desire to preserve its proportions. From the summit a good view may be had of the surrounding works and country.
The mounds which face the “Temple” on the west have great uniformity of figure and dimensions, and are highest in the rear, except E and I, which are nearly level on top. E, F, H, and I, have terraces in front; and all incline gently to the plain, which exhibits marks of excavation. In the rear and on the sides they are for the most part very abrupt. The pond in the rear is evidently artificial, and formed by removing the earth for building purposes. Extending around this pond are an embankment and ditch, (j k l,) the latter produced by the excavation of the earth for the embankment, which seems to have constituted a sort of levée around the pond to the high grounds at j and l.
“The mounds C, D have great similarity in their magnitude, form, and general position in respect to the “Temple;” but situated, as they are, in cultivated fields, their definite outlines are fast disappearing. B, however, differs essentially from the other mounds of the system; it is perfectly level on its summit, of gentle declivity and moderate height, and has been fitly chosen as the site of a dwelling-house, which fronts the area surrounded by the mounds.
“The several ponds have outlets for the water at particular points, which were probably controlled as the mound-builders desired. The long embankment (m n o) is abruptly cut off at o, but is continued again towards p, diminishing in magnitude as the land grows higher, until it almost disappears at s. The swale or low strip of ground which borders this embankment on the left, continues up to very near the pond at s, but has no actual connection with it. It does not appear that the large pond, within this grand levée, is artificial. The smaller ones, however, were manifestly produced by throwing up the earth around them, as at m n; s; t u, and v w.
“The necessity for these artificial ponds is apparent from the fact, that there are no streams or supplies of water nearer this prairie than five miles. Hence the excavations, usually made without apparent design in constructing the mounds, are at this place so economized as to produce the ponds in the immediate neighborhood. Here the conformation of the ground, which is gently undulating, rendered it easy to construct large ponds or lakes, to contain a perennial supply of water. This has plainly been the object of the extensive levées or embankments traced in the map. The general inclination of the land is southward, and the drains in its surface were with some skill called into aid.”
A similar mode of retaining a supply of water has already been remarked, in the case of a fortified hill, in Ohio. (See page [15].) The ancient inhabitants of Central America resorted to the same method. Their aguadas, lined with pavements and enclosed by embankments, are among the most interesting remains of ancient art. p115