mains of the Mound Builders are found in the New England States, nor even in the State of New York." ("North Americans of Antiquity," p. 28.) This would indicate that the civilization of this people advanced up the Mississippi River and spread out over its tributaries, but did not cross the Alleghany Mountains. They reached, however, far up the Missouri and Yellowstone rivers, and thence into Oregon. The head-waters of the Missouri became one of their great centres of population; but their chief sites were upon the Mississippi and Ohio rivers. In Wisconsin we find the northern central limit of their work; they seem to have occupied the southern counties of the State, and the western shores of Lake Michigan. Their circular mounds are found in Minnesota and Iowa, and some very large ones in Dakota. Illinois and Indiana were densely populated by them: it is believed that the vital centre of their colonies was near the junction of the Ohio and Mississippi rivers.
The chief characteristic of the Mound Builders was that from which they derived their name—the creation of great structures of earth or stone, not unlike the pyramids of Mexico and Egypt. Between Alton and East St. Louis is the great mound of Cahokia, which may be selected as a type of their works: it rises ninety-seven feet high, while its square sides are 700 and 500 feet respectively. There was a terrace on the south side 160 by 300 feet, reached by a graded way; the summit of the pyramid is flattened, affording a platform 200 by 450 feet. It will thus be seen that the area covered by the mound of Cahokia is about as large as that of the greatest pyramid of Egypt, Cheops, although its height is much less.
The number of monuments left by the Mound Builders is extraordinarily great. In Ohio alone there are more than ten thousand tumuli, and from one thousand to fifteen hundred enclosures. Their mounds were not cones but four-sided pyramids—their sides, like those of the Egyptian pyramids, corresponding with the cardinal points. (Foster's "Prehistoric Races," p. 112.)
