A peculiarity of the altar-mounds is that they are formed of regular strata of earth, gravel, sand, clay, etc., which are not horizontal, but follow the curve of the surface. The outer layer is commonly of gravel. This stratification renders it easy to detect any modern disturbance of the mounds, and makes the altar relics especially interesting and valuable for scientific purposes. Over the ashes in one altar-mound, were found plates of mica and some human bones. Skeletons are often found near the surface of these mounds, the strata above them being disturbed; in one case the Indians had penetrated to the centre and deposited a body on the altar itself. Sir John Lubbock inclines to the opinion that these were really sepulchral rather than sacrificial mounds, although he had not personally examined them. Whatever their use, they certainly constitute a clearly defined class distinct from all others, and the name altar-mounds is as appropriate as any other.
BURIAL MOUNDS.
Unstratified mounds, never within enclosures and generally at some little distance from them, containing human remains in their centres and undoubtedly erected as places of sepulture, constitute the second class, and are called burial mounds. The custom of heaping up a mound over the dead was probably imitated for a long time by the tribes that followed the Mound-builders, so that the relics from these mounds are less satisfactory than those found on the altars. In the burial mounds that may be most confidently ascribed to the Mound-builders, the human remains are found in a situation corresponding to that of the altars. They are usually enclosed in a frame-work of logs, a covering of bark or coarse matting, or a combination of these, which have left only faint traces. Of the skeleton only small fragments remain, which crumble on exposure to the air. In some cases there are indications that the body was burned before burial. Each mound contains, as a rule, a single skeleton, generally but not always placed east and west. Where several skeletons are found together, they are sometimes placed in a circle with the heads towards the centre. The mounds never contain large numbers of skeletons, and cannot be regarded as cemeteries, but only as monuments reared over the remains of personages high in rank. Very few skulls or bones are recovered sufficiently entire to give any idea of the Mound-builders' physique, and these few show no clearly defined differences from the modern Indian tribes. Four or five burial mounds are often found in a group, the smaller ones in such cases being grouped round a larger central one, generally in contact with its base. Mr Lapham sketched mounds in Wisconsin where the body is deposited in a central basin-shaped excavation in the ground very much like those in Vancouver Island already described.
Of the eastern burial deposits not connected with the mounds I shall say very little. It has already been stated that the mounds were in no sense cemeteries. Only a favored few of what must have been a dense population were honored by these sepulchral monuments. Obliged to seek elsewhere the general depositories of the dead, we find them of various classes in large numbers; but as yet very little has been done towards identifying any of them as the resting-places of the Mound-builders. There are many bone-pits, or trenches filled with human bones, in the mound region; but some of the modern Indians are well known to have periodically collected and deposited in pits the bones of their dead. Large numbers of bodies have been found in the caves of Kentucky and Tennessee, well preserved by the natural deposits of saltpetre, and wrapped in skins, bark, or feather-cloth; but the fact that such cloths were made and used by the southern tribes, renders the origin of these bodies uncertain. Besides the caves and trenches there are regular cemeteries, some of them very extensive. Seven of these are reported about Nashville, Tennessee, within a radius of ten miles, each being about a mile in extent. The graves are of flat stones, lie in ranges, and contain skeletons much decayed, with some relics. The coffins, or graves, vary from two to six feet in length, and the smallest have sometimes been mentioned as indicating a race of pigmies; it is evident, however, that in such graves bones were not deposited until the flesh had been removed. Sometimes there are traces of wooden coffins, in other cases there are only stones at the head and feet, and often there is no trace of any coffin. A few graves contain relics similar to those in the altar-mounds, and were covered with large forest trees when first seen by Europeans. Yet the comparatively well-preserved skeletons, and the presence in many cases of iron and relics clearly modern, render it well-nigh impossible to decide which, if any, of these cemeteries contain the remains of the Mound-builders.
Mound at Miamisburg.
ANOMALOUS MOUNDS.
Mounds of the third class are called anomalous, and include all that are not evidently either altar or burial mounds, or which have some of the peculiarities of both classes; for instance, in an elliptical mound an altar was found in one centre, and a skeleton in the other. Most prominent among them are the hill-top heaps of earth, or—oftener than in the plains below—of stone. These have as a rule few original burial deposits, and no relics; are often near fortifications; and in many cases bear the marks of fire. Their use cannot be accurately determined, but they are generally regarded as watch-towers and fire signal stations. Of course, comparatively few of the whole number of conical mounds have been explored, but so far as examined they seem to be about equally divided between the three classes. The mound shown in the cut is at Miamisburg, Ohio, and its class is not stated. It is sixty-eight feet high and eight hundred and fifty feet in circumference. Shell-mounds abounding in relics of aboriginal work are very numerous in the gulf states.
I shall pass briefly over the minor relics of aboriginal art since it is impossible in this volume to present illustrative cuts of the thousands of objects that have been found, or even of typical specimens. Such relics as are incontestably the work of the Mound-builders include articles of metal, stone, earthen ware, bone, and shell. They include implements and ornaments, besides which many are of unknown use. Most of the smaller specimens, whose use is unknown, are called by Mr Dickeson and others aboriginal coins; perhaps some of them did serve such a purpose.