Great Serpent Mound.— Of these animal form structures one of the largest and most noted is the Great Serpent Mound in Adams County, Ohio, which contains 1,350 feet of wall and is so constructed that it might, at one time, have formed a defensive work. The central folds of the serpent make two fort-like en closures open only at the back; while the coil of the tail, which is whorl-shape, is especially well arranged for defensive purposes, the swollen head and neck, the outline of which is formed of earthen walls, constitute a very extensive fort-like structure, divided in two parts by a wall similar to that of the rest of the structure. Within the larger of these two divisions is an oval enclosure of considerable extent formed by earthen walls similar to those of the rest of the edifice. In the outer wall of the head section is an opening leading into the larger subdivision; but the other sections and the oval enclosure are without openings of any kind. The whole structure is admirably laid out for defensive purposes. It may, and prob ably did have a three-fold purpose, defense, totemic representation and religious significa tion. The wall is now only five feet high, but it may have been originally somewhat higher.
Situation of Chief Mounds.— In the United States there are still a vast number of mounds; and in the State of Ohio there were, at one time, thousands. The smallest of these, how ever, have disappeared or are rapidly being leveled to the ground by the ploughman. Some groups of mounds, like those that formed the basis for a part of the city of Saint Louis, Mo., have been leveled and built tip over. In Wis consin are large numbers of mounds represent ing the forms of animals, while in Tennessee are smaller mounds which were used for burial purposes, as is clearly proved by the stone graves they contain. Some of these seem to have been either community, tribal or family burial places, as considerable numbers of graves have been found in a single mound. Burial tumuli were also erected in Illinois, Minnesota, Mississippi, Indiana, Florida, Wisconsin, Vir ginia, Kentucky and Missouri. The mountain ranges seem to have set a limit to the mound builder activity which did not extend to the east of the Alleghenies, North Tennessee and North Carolina. Some of the mounds of the mound-building regions were old when they first became known to the white explorers, but how old is not known. Indian races in various parts of America were still occupying mounds a century after the discovery of America and some of them were constructing them both for burial purposes and as foundations for build ings; but it seems to be uncertain whether any of these later constructions were used for re ligious purposes. Some tribes are also known to have built, in historical times, miniature mounds in their great council houses, ap parently as a part of a religious ceremony.
This calls to mind the fact that the Mixtecas and Zapotecas represented the sacred mound as the symbolical presentation of the ((heart of heaven." Among other tribes the custom obtained of collecting the bones of the dead, cleaning them carefully and burying them in a common grave over which a mound was erected.
It is evident from the great variety of mound structures that they could not have all been constructed by the same tribe or race and that the erection covered a very considerable period of time most of which was comprised in the later Stone Age of which some of the mounds show some beautiful workmanship; hut nothing in metal except that introduced into them later of European make, and a few things probably obtained by barter from southern races.
Cahokia Mound is the largest prehistoric artificial earthwork in the United States. It is in Madison County, not far from Saint Louis; it lies in the American bottoms and is sur rounded by a number of smaller mounds which Brackenridge, who visited Cahokia and the complete mound neighborhood in 1811, asserts then numbered 45, exclusive of a great many smaller elevations. These probably did not in clude the mounds that existed at one time on the site of Saint Louis, Mo., and which gave that city the title of the "Mound City.° he Cahokia truncated pyramid, for such it really is, measures about 1,000 feet from north to south, 725 from east to west, and 100 feet high at its greatest elevation. But the level top of the mound is not all at the same elevation. In fact one section of it is only 30 feet high, another is over 60 feet, while a third and fourth are slightly lower than the summit. The total Cahokia terrace measures about 200 feet by 500 feet. It thus affords considerable space, nearly two and one-half acres, which was orob ably used as a foundation for edifices. The base of Cahokia covers 17 acres, or over 40 per cent more than Cheops, the greatest of the Egyptian pyramids. Situated in the midst of a very populous district, and commanding the great "bottoms* from, which rose scores of mounds of all sizes, Cahokia must have pre sented an inspiring sight in the days of its prosperity and Might. The great pyramid was constructed of earth, which was taken from the country surrounding it, as is evident from the depressions in the soil. Cahokia is sometimes called Monks' Mound because it was occupied for a considerable time, from the beginning of the 19th century on, by Trappist monks, who had a vegetable garden on the top of the mound. Next to Cholula (q.v.), Cahokia is the largest based artificial pyramid in North America.