10 GEOLOGY OF OHIO. 



mouth of the Muskingum River where they are so large, or are found in 

 connection with the enclosures belonging to the middle Ohio Valley. 



The topographical markings in the figure will show that, whatever 

 may have been the design of this particular group, it occupies nearly all 

 the available level ground in the plain on which it is erected. While this 

 fact does not necessarily reinforce any of the theories above set forth, as 

 to the purpose of such works, the adherents to some of them will find 

 difficulty in providing sufficient space for the town or village and culti- 

 vable ground necessary for the accommodation of those by whom the 

 structure is supposed to have been reserved for only occasional or tem- 

 porary use. 



Numerous other groups in the state are worthy of separate mention; 

 but as a large volume would be required to contain all that might be 

 properly said regarding them, this sketch must suffice. Some are so 

 complicated in arrangement as to suggest the idea of a labyrinth; others, 

 more simple in form, are in such situations as to render approach to them 

 inconvenient or even difficult. In extent they range from those meas- 

 ured by square miles to those which are contained within an area of two 

 or three acres. 



(b.) HIIX-TOP ENCLOSURES. 



The second division is intended to include only the larger enclosures, 

 on high ground, in the same section of the State containing those just 

 described. The difficulties in the way of accounting for the uses of the 

 former do not exist with the latter. To all who examine carefully their 

 locations it is evident they were intended for defensive structures. 

 Whether composed entirely of stone, or of earth, or of both combined; 

 whether confined to a plateau or extending down the hill-side below; 

 whether having a ditch, either interior or exterior, or rising directly from 

 a level surface; — in all, the method of construction and their position 

 relative to the surrounding country, make it obvious they were intended 

 as a place of refuge in time of danger from foes. Many of them com- 

 mand extensive views in every direction, notably the one on Spruce Hill, 

 nearly opposite the village of Bourneville, which overlooks the valley of 

 Paint Creek from the hills along the Scioto to the high land about Hills- 

 boro, as well as the region for many miles north and south. This fortifi- 

 cation is indicated at C in Plate II, and is shown in detail in Plate VII. 

 The hill on which it stands is a long, narrow spur projecting from the 

 table-land to the south, with steep, in some places almost precipitous, 

 sides. The wall, composed entirely of boulders and cobblestones, result- 

 ing from disintegration of the sandstone strata at and near the surface, 

 closely follows the margin of the level summit at every point except 

 where the lines connecting the ends is carried across. It was only from 

 this direction that danger need be apprehended by the inmates, as no 

 other portion of the enclosure could be reached except by a tedious ascent 



