be verified by a series of borings. In this part of its course Mad 

 river receives a number of tributaries from either side, the most con- 

 siderable on the east being Macachack, Kingscreek and Pleasant- 

 run, and on the west Griady's creek and Muddy creek, which drain the 

 high land near Spring Hills, and, proceeding south, Spring, Nettle 

 and Stormes creeks, and Black Snake run, on the borders of Clarke 

 county.* 



The country drained by these tributaries is mostly of a gently 

 undulating character, the knolls being composed of clay, sand and 

 gravel, the materials of which have been largely furnished by the 

 rocks of Ohio. There are also a number of well-marked terraces 

 where the gravels are overspread with a rich alluvial soil, either with 

 or without an intervening stratum of clay. Along the valley of 

 Buck creek, in the eastern part of Clarke county, the gravel hills 

 slope gently down to the level of the broad plain in which the 

 stream lies, presenting a very picturesque appearance. In the opin- 

 ion of President Orton these ridges are not the remains of a general 

 superficial deposit, but were laid down during the period of the 

 post-glacial in the same form that they now possess.* 



The shape and general appearance of the ridges certainly 

 favor such a supposition. Their gentle and uniform slope, the 

 numerous gorges which penetrate their sides giving to them 

 a peninsula-like form but having apparently no present connec- 

 tion with the drainage system, the occasional depressions found 

 upon their summits, all these conditions seem to favor the 

 notion that they were deposited in strong counter currents of 

 water very much as we see gravel banks forming along the course of 

 our rivers at the present day. The examination, however, which the 

 writer has made of sections of several of these gravel hills in the 

 neighborhood of Catawba station, on the C. C. C. & I. R. R., and at 

 Baldwin's mill, do not seem to corroborate this theory. In these sec- 

 tions the horizontal lines of stratification are clearly seen, and in every 

 instance the strata run quite to the edge of the hill where they termin- 

 ate abruptly in the thin surface covering of the soil. These ridges 

 are the favorite sites selected by the Mound-builders for their struct- 



*I am informed by Col. J. H. James that the present Dugan's run, emptying into 

 Mad river south-west of Urbana, is an artificial tributary resulting from the construction 

 of a drain from a marshy tract of land known as Dugan's prairie. In constructing the 

 ditch it was necessary to cut through a ridge, and the natural drainage was formerly, 

 probably toward Buck creek. 



jState Geological Survey, Vol. 1, p. 459. 



