As we drew near to St. Louis, we passed the wide low plains upon which is situated the great Cahokia Mound. As it was my purpose to make an expedition to that part of Illinois before proceeding to the upper part of the Mississippi Valley, I went there a few days after we had landed from the steamer.
The mound when seen from the plains, stands out from them in a manner so isolated and prominent, that it seems at the first glance, to be unquestionable that it must have been raised by human labour; but upon a closer investigation there are good reasons for believing it to be a natural formation of the land, shaped originally like a rounded hillock, and subsequently terraced and altered in such a manner as to make it appear to be altogether artificial. It is ninety feet high, and the base, if the whole of the irregular and spreading area is included, covers a space of about nine acres. The summit is level, and contains nearly two acres. Upon this was established a substantial farmhouse, which I found to be tenanted by a kind and hospitable family, who were evidently in a prosperous condition, and able to cultivate their land advantageously.
The hillock has been given locally the name of Monks Mound, in consequence of its having been for several years the site of a small monastery, belonging to some of the brethren of La Trappe, who, towards the close of the last century, emigrated to this remote spot when the monastic orders were suppressed during the French Revolution. The monks used the lower slopes as a garden, and there still remain the indications of the terraced ground which was used by them for their solitary walks. The Trappists are supposed to have left Cahokia at the time of the restoration of the Bourbons. Probably they returned to France when the Monastery of La Trappe was re-established, in the reign of Louis XVIII.
Before the mound was used as a farm there was on its summit an Indian tumulus. The farmer taking a practical view of this burial heap, destroyed it and spread the contents over his land.
The accompanying sketch of the mounds was taken from the slope of the Cahokia Mound, at a height of about forty feet above the plain. It represents what now remains of these singular earthworks; they must originally have been much more numerous.
On the plain below, there exists a remarkable group of circular and platform mounds, which, in consequence of their unusual position and ground plan, demand careful attention. They differ from the earthworks in Ohio, and appear to have been raised by a tribe having exceptional customs and habits of life. The mounds are not surrounded by any embankments, and were entirely unprotected. They were probably raised to make high platforms for the dwellings of the chiefs. One of them was used, at the time of my visit to Cahokia, as the site of the village schoolhouse.
I endeavoured to trace the plan of the ancient inclosure, which contained a group of the greatest archæological importance, but so many of the mounds had been levelled, that it was difficult to form definite conclusions with regard to its shape or extent. It seems to have been an irregular parallelogram, about fifteen hundred yards in length, having at each end a large earthwork or mound, with a wide and well levelled platform on the top. In the centre, there were two conical mounds, which must have been raised in that position for some important purpose. They were each about forty feet high, and appeared to have been so placed as to dominate the mounds forming the sides of the inclosure. The men farming the adjacent plains, stated that there had been a large number of small burial mounds on their lands, most of which had been destroyed. They had found in them quantities of bones and skulls, but no ornaments or stone weapons.
When ploughing the ground, they had seen below the surface, fragments of rude pottery and many flint arrow heads. A large and highly polished stone spear head was discovered near the settlement and given by the finder to the young American lady who was then acting as teacher at the school house on the mound. It was a hard kind of flinty chert, and was a singularly fine specimen of Indian workmanship.[31]