Two sand strata occur in this mound, the first five feet below the surface, the second one foot deeper. The intermediate layers of earth presented the mottled appearance already explained, and were much compacted, rendering excavation exceedingly slow and laborious. The remaining shafts were afterwards sunk for the purpose of ascertaining the size and form of the altar, but disclosed nothing of importance in their course.
Fig. 35.—Longitudinal section of altar.
Although the altar in this mound was not fully exposed, yet enough was uncovered to ascertain very nearly its character and extent. Forty-five feet of its length was exposed, and in one place its entire width, which was eight feet across the top, by fifteen at the base. The portions in the section, extending beyond the line of the excavation, are supplied, giving an entire length to the altar of not far from sixty feet.
Fig. 36.—Cross section of altar.
By attention to the longitudinal section of the altar B C B, it will be seen that it shelves gradually from the ends, forming a basin of not far from eighteen inches in depth. The outer slope is more gradual than the inner one. Near the centre of the altar, two partitions, A A, are carried across it transversely, forming a minor basin or compartment, C, eight feet square. Within this basin the relics deposited in the mound were placed. The outer compartments seemed to have been filled with earth, previous to the final heaping over, so as to present a perfectly level surface, which had been slightly burned. This feature is indicated in the section, which also illustrates another interesting and important peculiarity. Upon penetrating the altar (a task of no little difficulty in consequence of its extreme hardness) to ascertain its thickness, it was found to be burned to the depth of twenty-two inches. This could hardly be accounted for by the application or continuance of any degree of heat from above, and was therefore the occasion of some surprise. A more minute examination furnished the explanation. It was found that one altar had been built upon another; as if one had been used for a time, until, from defect or other causes, it was abandoned, when another was recast upon it. This process, as shown in the section F E, had been repeated three times, the outline of each successive layer being so distinct as to admit of no doubt as to its cause. The partitions A A were constructed subsequently to the erection of the altar, as is evidenced from the fact that they were scarcely burned through, while the altar immediately beneath them was burned to great hardness. Scattered upon the deposit of earth filling the compartments D D, and resting upon p151 the slopes of the altar, were found the traces of a number of pieces of timber, four or five feet long, and six or eight inches thick. They had been somewhat burned, and the carbonized surface had preserved their casts in the hard earth, although the wood had entirely decayed. They had been heaped over while glowing, for the earth around them was slightly baked. In fact the entire hollow of the altar was covered with a thin layer of fine carbonaceous matter, much like that formed by the burning of leaves or straw. These pieces had been of nearly uniform length; and this circumstance, joined to the position in which they occurred in respect to each other and to the altar, would almost justify the inference that they had supported some funeral or sacrificial pile.
The remains found in this mound were, in their number and variety, commensurate with the labor and care bestowed on its construction. A quantity of pottery and many implements of copper and stone were deposited on the altar, intermixed with much coal and ashes. They had all been subjected to a strong heat, which had broken up most of those which could be thus affected by its action. A large number of spear-heads, as they have been termed, beautifully chipped out of quartz and manganese garnet, had been placed here; but, out of a bushel or two of fragments, four specimens only were recovered entire. One of them is faithfully figured under the head of “Implements.” A quantity of the raw material, from which they were manufactured, was also found, consisting of large fragments of quartz and of crystals of garnet. Some of these crystals had been of large size, certainly not less than three or four inches in diameter. A single arrow-point of obsidian was found; also a number of fine arrow-heads of limpid quartz. One of these was four inches in length, and all were finely wrought. Judging from the quantity of fragments, some fifty or a hundred of these were originally deposited on the altar. Among the fragments were some large thin pieces of the same material, shaped like the blade of a knife. Two copper gravers or chisels, one measuring six, the other eight inches in length, (see “Implements,”) also twenty or more tubes formed of thin strips of copper, an inch and a quarter long by three eighths of an inch diameter, (see “Ornaments,”) were found among the remains. A large quantity of pottery, much broken up, enough perhaps to have formed originally a dozen vessels of moderate size, was also discovered. Two vases have been very nearly restored. They resemble, in material and form, those already mentioned, and have similar markings on their exterior. (See “Pottery.”) Also a couple of carved pipes; one of which, of beautiful model and fine finish, is cut out of a stone closely resembling, if indeed not identical with, the Potomac marble, of which the columns of the hall of the House of Representatives at Washington are made. The other is a bold figure of a bird, resembling the toucan, cut in white limestone.
A portion of the contents of this mound were cemented together by a tufa-like substance of a gray color, resembling the scoriæ of a furnace, and of great hardness. It was at first supposed to be carbonate of lime gradually deposited, in the lapse of time, from the water percolating through the outer stratum of limestone gravel and pebbles. The quantity however, covering as it did a large part of the basin to the depth of an inch or two, weighed strongly against such a conclusion; and a subsequent analysis demonstrated that it was made up in part of phosphates. A p152 single fragment of partially calcined bone was found on the altar. It was the patella of the human skeleton.
Such were the more important features of this interesting mound. It is evident that the enclosed altar had been often used, and several times remodelled, before it was finally heaped over. Why this was at last done, upon what occasion, and with what strange ceremonies, are questions which will probably forever remain unanswered.