OF THE MISSISSIPPI VALLEY. 19
has an outwork of crescent shape, the ends of which ap- proach within a short distance of the brow of the hill.
The excavations are near the gateways: none of them are more than sixty feet over, nor have they any considera- ble depth. Nevertheless they all, with the exception of the one nearest to gateway S, contain water for the greater portion if not the whole of the year. A pole may be thrust eight or ten feet into the soft mud at the bottom of those at B.
At S and H, terminating the parapet, are mounds of stones, thrown loosely together, eight feet in height. Thirty rods distant from gateway N, and exterior to the work, is a mound ten feet high, on which trees of the largest size are growing. It was partially excavated a number of years ago, and a quantity of stones taken out, all of which seemed to have undergone the action of fire.
The ground in the interior of the work gradually rises, as indicated in the section, to the height of twenty-six feet above the base of the wall, and overlooks the entire adja- cent country. In the vicinity of this work, are a number of others occupying the valley—no less than six, of large size, occurring within a distance of six miles down the river.
The character of this structure is too obvious to admit of doubt. The position which it occupies is naturally strong, and no mean degree of skill is employed in its arti- ficial defences. Every accessible avenue is strongly guard- ed. The principal approach, the only point of easy access, or capable of successful assault, is rendered doubly secure. A mound, used perhaps as an alarm post, is placed da short distance in advance, and a crescent wall crosses the isthmus, leaving but narrow passages between its ends and the steeps on either hand. Next comes the principal wall of the enclosure. In event of an attack, even though both these defences were forced, there still remained a series of walls so complicated as inevitably to distract and bewilder the assailants, thus giving a marked advantage to the defenders. This advantage may have been regarded as more consider-
