644 THE ICE AGE IN NORTH AMERICA. 



city. The general height of the hills in that vicinity above 

 the river is from four hundred to five hundred feet. But 

 the hills just north of Cincinnati are separated from the 

 general elevation farther back by the depression referred to, 

 in which Madison ville is situated. 



The depression is from one to two miles wide, and about 

 live miles long, from one stream to the other, and is occu- 

 pied by a deposit of gravel, sand, and loam, clearly enough 

 belonging to the Glacial-terrace epoch. Recent investigations 

 make it probable that the Ohio formerly flowed north through 

 Mill Creek, and joined the Great Miami near Hamilton. The 

 surface of this is generally level, and is about two hundred 

 feet above the low-water mark in the Ohio. On the east 

 side, on the Little Miami River, at Red Bank, opposite Madi- 

 son ville, the gravel is coarse, merging into pebbles from one 

 to three or four inches through, interstratitied with sand, and 

 underlaid, near the river-level, with fine clay. There is here 

 a thin covering of loess, or fine loam. On going westward 

 this loess-deposit increases in thickness, being at Madison- 

 ville, one mile west, about eight feet thick. Farther west 

 it is much deeper, and seems to take the place of the gravel 

 entirely. At several railroad cuttings, compact glacial clay 

 appears underneath all. 



Thus, it is evident that this cross-valley, connecting Mill 

 Creek with the Little Miami back of Avondale, Walnut 

 Hills and the observatory, was once much deeper than now, 

 and has been filled in with deposits made when immense 

 glacial floods were pouring down these two streams from the 

 north. The Little Miami was a very important line of glacial 

 drainage, as is shown by the extensive gravel-terraces all along 

 its course, to which the railroads resort for ballast. The 

 coarser material was deposited near the direct line of drainage, 

 where the current was strong, while back from the river to- 

 ward Madison ville, there was naturally an increase of the fine 

 deposit, or loess, which is practically a still-water formation. 



In making an excavation for a cistern. Dr. Metz pene- 

 trated the loess, just described, eight feet before reaching 



