I begin with the embankments and enclosures. They are found, almost always in connection with mounds of some class, on the hills overlooking the valleys, and on the ravine-bounded terraces left by the current of rapid streams. The first, or oldest, terraces, with bold banks from fifty to a hundred feet high, furnish the sites of most of the works; on the lower intermediate terraces, whose banks range from ten to thirty feet in height, they are also found, though less frequently than above; while on the last-formed terrace below no monuments whatever have ever been discovered.
The embankments are simply earth, stones, or a mixture of the two, in their natural condition, thrown up from the material which is nearest at hand. There is no instance of walls built of stone that has been hewn or otherwise artificially prepared, of the use of mortar, of even rough stones laid with regularity, of adobes or earth otherwise prepared, or of material brought from any great distance. The material was taken from a ditch that often accompanies the embankment, from excavations or pits in the immediate vicinity, or is scraped up from the surface of the surrounding soil. There is nothing in the present appearance of these works to indicate any difference in their original form from that naturally given to earth-works thrown up from a ditch, with sides as nearly perpendicular as the nature of the material will permit. Of course, any attempt on the part of the builders to give a symmetrical superficial contour to the works would have been long since obliterated by the action of the elements; but nothing now remains to show that they attached any importance whatever to either material or contour. Stone embankments are rarely found, and only in localities where the abundance of the material would naturally suggest its use. In a few instances clay has been obtained at a little distance, or dug from beneath the surface.
FORTIFIED HILLS.
Accordingly as they are found on the level plain, or on hill-tops or other strong positions, enclosures are divided into fortifications and sacred enclosures. Of the design of the first class there can be no doubt, and very little respecting many of the second class, although it is very probable that some of the latter had a different purpose, not now understood. Naturally some works occur which have some of the features of both classes. The fortifications are always of irregular form as determined by the nature of the ground.
Fortification—Butler Hill.
A fortification at Butler Hill, near Hamilton, Ohio, is shown in the cut. The summit of the hill is two hundred and fifty feet above the river, the enclosing wall is of earth and stones, five feet high, thirty-five feet thick at the base, and unaccompanied by a ditch, although there are some pits which furnished the material of the wall. Two mounds or heaps of rough stones are seen within the enclosure and one without, the stones of all showing marks of fire.
