ANCIENT WORKS NEAR ROCK RIVER. 43 



depth to leave a trace at the present time. If we allow for difference of exposure 

 of earth thrown up into a ridge and that lying on the original flat surface, we can 

 perceive no difference between the soil composing the ridge and that found along 

 its sides. Both consist of a light yellowish sandy loam. 



The ridge forming the inclosure is 631 feet long at the north end, 1,419 feet long 

 on the west side, and 700 feet on the south side ; making a total length of wall of 

 2,750 feet. The ridge or wall is about 22 feet wide, and from one foot to five in height. 



The wall of earth is enlarged on the outside, at nearly regular distances, by 

 mounds of the same material. They are called buttresses or bastions; but it is 

 quite clear that they were never designed for either of the purposes indicated by 

 these names. The distance from one to another varies from sixty-one to ninety-five 

 feet, scarcely any two of them being alike. Their mean distance apart is eighty- 

 two feet. They are about forty feet in diameter, and from two to five feet high. 

 On the north wall, and on most of the west wall, they have the same height as the 

 connecting ridge ; but on the south wall, and the southern portion of the west wall, 

 they are higher than the ridge, and at a little distance resemble a simple row of 

 mounds. 



On the inner side of the wall, opposite many of these mounds, is a slight depres- 

 sion or sinus ; possiblj'^ the remains of a sloping way by which the wall was ascended 

 from within the inclosure. 



The two outworks, near the southwest angle of the great inclosure, are con- 

 structed in the same manner; but both these mounds and the connecting ridge are 

 of smaller dimensions. The ridge or way connecting the mounds at a and c, has 

 something of the same general character, though still more obscure. When viewed 

 from the road, a short distance west, these outworks would be supposed to be 

 nothing more than a few circular mounds. The connecting ridge, at least, is too 

 insignificant to be mistaken for the walls of a fort, or other work of defence. 

 Whether these walls are only a series of ordinary mounds, such as are found all 

 over the western country, differing only in being united one to another, it may 

 perhaps be difficult to decide. They may possibly have been designed for the same 

 and for other purposes. 



On opening the walls near the top, it is occasionally found that the earth has 

 been burned. Irregular masses of hard reddish clay, full of cavities, bear distinct 

 impressions of straw, or rather wild hay, with which they had been mixed before 

 burning. These places are of no very considerable extent, nor are they more than 

 six inches in depth. Fragments of the same kind are found scattered about; and 

 they have been observed in other localities at a great distance from these aiacient 

 ruins. 



This is the only foundation for calling these " brick walls." The " bricks" were 

 never made into any regular form, and it is even doubtful whether the burning 

 did not take place in the wall after it was built. The impression of the grass is 

 sometimes so distinct as to show its minute structure, and also that it was of the 

 angular stems and leaves of the species of carex still growing abundantly along the 

 margin of the river. As indicating the probable origin of this burned clay, it is 

 important to state, tliat it is usually mixed with pieces of charcoal, partially burned 



