The peculiar feature, however, is the altar at the bottom of the mound, directly above the natural surface of the ground. The small cut gives us a clear idea of the altar, the light lines running around it showing the plan. These altars are almost always composed of clay, though some of stone have been discovered. They are of various shapes and sizes. We notice the dish-shaped depression on the top of the altar. The clay of which they are composed seems to have been moulded into shape directly over the surface of the ground. Sometimes a layer of sand was put down as a foundation. They are nearly always thoroughly burned, the clay being baked hard, sometimes to the depth of fifteen or twenty inches. This must have required intense and long continued heat.
We are at once curious to know the object of this altar. Within the basin-shaped depression are generally found all manner of remains. Sometimes portions of bones, or fragments of wood, arranged in regular order; pieces of pottery vessels, and implements of copper and stone; spear-heads, arrow-heads, and fragments of quartz and crystals of garnet. Pipes are a common find, carved in miniature figures of animals, birds, and reptiles. Two altar-mounds but recently examined near Cincinnati had altars about four feet square that were loaded down with ornaments.
One especially contained quantities of ornaments of stone, copper, mica, shells, the canine-teeth of bears and other animals, and thousands of pearls. They were nearly all perforated, as if for suspension. Several of the copper ornaments were covered with native silver which had been hammered out into thin sheets and folded over the copper. One small copper pendant seems to have been covered with a thin sheet of hammered gold, as a small piece was still clinging to it. This is the first example of finding native gold in the mounds.19 On this altar were also found masses of meteoric iron, and ornaments of the same material. One piece of mica showed the profile of a face.20
In all cases the articles found on the altars show the action of fire. We seem justified, then, in supposing that after the altar was formed, fires were lit on them, and into this fire were thrown the various articles just enumerated. But what was all this for? This will probably never be very clear to us, beyond the fact that it was a religious rite. Portions of the human skeleton have been found on these altars, and it has been suggested that human victims were at times part of the sacrifice; but as it is known that this people practised cremation, it may be that the altars were sometimes used for that purpose, the remains being afterwards gathered and buried elsewhere.
After the offerings had been flung into the fire, while it was yet glowing on the altar, earth or sand was heaped over them for a few inches, then successive layers of earth and sand, or ashes, clay, or gravel. Sometimes the altars were used several different times, in which case a layer of clay several inches thick was laid over the old altar. In one case three layers had been burned in before the final addition of earth and sand were heaped over it. These strange monuments of a by-gone people hint to us of mysterious rites. We wish we had more positive knowledge of the ceremonies they commemorated; but at present we must rest satisfied with conjecture.
The next class of mounds are known as burial mounds, some of which are stratified, and resemble the so-called altar mounds. A mound explored in Butler County, Ohio, had in the center a layer of clay an inch thick, which had been burned until it was red. Underneath this was another layer of clay, beneath which was found charcoal, burnt cloth, and charred bones. Mr. Foster thinks that in this mound the body was placed on a rude altar, fires were lit, and that while yet burning, clay was thrown over it all, and that then fires were built all over the mound, sufficient to burn the clay for an inch in thickness.21 We have also a description of a group of mounds explored near the Mississippi River, in which there were evident signs of cremation. At least in several mounds fires had been built close above the bodies. But in cremation other victims may have been burned to accompany the departed chiefs or warriors. In one mound evidence of such a custom was observed.
In another mound the center was found to be a mass of burned clay interspersed with calcined human bones. No less than ten or fifteen bodies had been burned here. “They must have worshiped some fierce ideal deity, and the ceremony must have been considered of great importance to have required so many victims.” This may have been, however, nothing more than simple cremation.22
Pidgeon has described mounds in Minnesota, in many respects like the altar mounds. In one case he mentions there was an altar or pavement of stone on the original surface of the ground, a few feet above which was a layer of clay, showing the action of fierce and long-continued fires. We furthermore are told that cremation, especially of chiefs, was more or less common among the Village Indians of North America, that similar usage was observed among many of the tribes of Mexico, and that the Mayas, of Yucatan, burnt the bodies of their lords, and built temples over their remains. So it may be that the altar mounds are but varieties of funeral mounds, the remains of the bodies burned here being buried elsewhere.23
