OF? THE. MISSISSIPPE VALLEY. 15
there have been individual explorers ; one maintaining that all the enclosures were intended for defence, while another persists that none could possibly have been designed for any such purpose. A sufficiently extended investigation would have shown, however, that while certain works possess features demonstrating incontestably a warlike origin, others were connected with the superstitions of the builders, or designed for purposes not readily apparent in our present state of knowledge concerning them.
It has already been remarked that the square and the circle, separate or in combination, were favorite figures with the mound-builders ; and a large proportion of their works in the Scioto valley and in Ohio are of these forms. Most of the circular works are small, varying from 250 to 300 feet in diameter, while others are a mile or more in circuit. Some stand isolated, but most in connection with one or more mounds, of greater or less dimensions, or in connection with other more complicated works. Wherever the circles occur, if there be a fosse or ditch, it is almost invariably interior to the parapet. Instances are frequent where no ditch is discernible, and where it is evi- dent that the earth composing the parapet was brought from a distance or taken up evenly from the surface. In the square or irregular works, if there be a fosse at all, it is exterior to the embankment, except in the case of fortified hills, when the earth, for the best of reasons, is usually thrown from the interior. These facts are not without their importance in determining the character and purpose of these remains. Another fact bearing directly upon the degree of knowledge possessed by the builders is, that many if not most of the circular works are perfect circles, and that many of the rectangular works are accurate squares. This fact has been demonstrated, in numerous instances, by careful admeasurements, and has been remarked in cases where the works embrace an area of many acres, and where the embankments or circumyallations are a mile or upwards in extent.
