10 ABORIGINAL MONUMENTS
Iowa, North and South Carolina, and in the Mexican terri- tory, beyond the Rio Grande del Norte. In short, they occupy the entire basin of the Mississippi and its tribu- taries, as also the fertile plains along the Gulf.
It is not to be understood that these remains are dis- persed equally over the area here defined. They are main- ly confined to the valleys of the streams, occupying the level, fertile terraces, and seldom occuring very far back from them.
Their number is well calculated to excite surprise, and has been adduced in support of the hypothesis—which has not been without its advocates—that they are most, if not all of them, natural formations, “the results of diluvial action,’ modified perhaps, in a few instances, but never erected by man. Of course no such hypothesis was ever advanced by any individual who had enjoyed the opportu- nity of examining these remains for himself.
Some estimate may be formed of their great abundance, in certain portions of the country, by an inspection of the accompanying Map, which exhibits a section of twelve miles of the Scioto valley. It will be observed that not less than ten large groups of earth-works occur within the space designated, besides which there is a large number of mounds and lesser monuments. Twenty-four of these mounds are found within a single enclosure, H, three miles above the city of Chillicothe. The large works, H and K, have each not far from two miles of embankment, and enclose little less than one hundred acres. Not far from one hun- dred enclosures and five hundred mounds are found in Ross county, Ohio, alone ; and the remains of the State may be safely estimated at ten thousand mounds and one thousand or fifteen hundred enclosures, of all sizes. Many of them are, of course, small, but cannot be omitted in an enumeration.
Nor is their magnitude less a matter of surprise than their numbers. Lines of embankment, varying in height from five to fifteen feet, and enclosing areas of from one to
