OF THE MISSISSIPPI VALLEY. 31
long by twelve and fifteen wide. The usual dimensions are from five to eight feet. All appear to have been mo- delled of fine clay, brought to the spot from a distance, and rest upon the original surface of the earth. In a few instances, a layer or small elevation of sand had been laid down, upon which the altar was formed. The elevation of the altars, nevertheless, seldom exceeds a foot or twenty inches, above the adjacent level. The clay of which they are composed is usually burned hard, sometimes to the depth of ten, fifteen, and even twenty inches. This is hardly to be explained, by any degree or continuance of heat, though it is manifest that in some cases the heat was intense. On the other hand, a number of these altars have been noticed, which are very slightly burned; and such, it is a remarkable fact, are destitute of remains.
The characteristics of this class of mounds will be best explained, by reference to the accompanying illustrations. It should be remarked, however, that no two are alike in all their details.
The mound, a section of which is here given, occurs in “Mound City,” a name given to a group of twenty-six mounds, embraced in one enclosure, on the banks of the Scioto river, three miles above the town of Chillicothe. It is seven feet high by fifty-five feet base. A shaft, five feet square, was sunk from its apex, with the following results :—
Ist. Occurred a layer of coarse gravel and pebbles, which appeared to have been taken from deep pits, sur- rounding the enclosure, or from the bank of the river. This layer was one foot in thickness.
2d. Beneath this layer of gravel and pebbles, to the depth of two feet, the earth was homogeneous, though slightly mottled, as if taken up and deposited in small loads, from different localities. In one place appeared a deposit of dark colored, surface loam, and by its side, or covering it, there was a mass of the clayey soil of greater depth.
