i 9 2 THE POPULAR SCIENCE MONTHLY. 



shallowness of the present rocky gorge of the Ohio between Cin- 

 cinnati * and the mouth of the Great Miami. The relative nar- 

 rowness also of the latter opening between the rocky escarpments 

 is readily visible to the transient traveler, Mill Creek Valley be- 

 ing about twice as wide as that of the Ohio for fifteen or twenty 

 miles below the mouth of the creek ; while a low passage joins 

 Mill Creek at Ludlow Grove which sweeps around north of Wal- 

 nut Hills, and enters the Ohio through the valley of the Little 

 Miami Walnut Hills, Mount Auburn, and Mount Lookout, the 

 principal residence portions of the city, being upon a high, rocky 

 pedestal completely surrounded by a depression which has at 

 some time been produced by river erosion. 



This valley from Cincinnati to Hamilton is now filled with 

 gravel and clay to a great depth. Upon inquiring for the extent 

 to which the old channel had been filled, it was found by the 

 wells which had been sunk in it that the rock bottom descends 

 from Cincinnati to Hamilton, and is considerably lower than the 

 rock bottom of the present Ohio below Mill Creek. Near Ludlow 

 Grove the bed rock is at least sixty feet below present low water 

 in the Ohio. A few miles farther north, at Ivorydale, on Mill 

 Creek, the bed rock where reached was found to be thirty-four 

 feet below low-water mark in the Ohio, while there was nothing 

 to show that in other portions of the valley the gravel was not 

 still deeper. At Hamilton the bed rock was found to be at least 

 ninety-one feet below the bottom of the Ohio River, showing that 

 there is a deeply buried channel through Mill Creek Valley from 

 Cincinnati to Hamilton ; while, according to the inspector, Mr. C. 

 J. Bates, upon building the piers for the great bridge of the Cin- 

 cinnati Southern Railroad, which crosses the Ohio River near the 

 west end of the city, it was found that the rock bottom was 

 everywhere within a few feet of the low- water mark ; thus fully 

 justifying the inference of Prof. James, which can best be given 

 in his own words : 



" . . . Previous to the Glacial period a barrier of land extended 

 from Price Hill on the north to the mouth of the Licking River 

 on the south, preventing the westward flow of the Ohio, and forc- 

 ing it north and northwest along the channels of Mill Creek and 

 Duck Creek. These met at Ludlow Grove (near Cummingsville) 

 and together continued north to Hamilton. Here entered the 

 Great Miami, and the united streams continued in great volume 

 southward to the present channel of the Ohio, at Lawrenceburg. 



" At the coming on of the Glacial period a tongue of ice pro- 

 jecting down the valley from the north and surrounding the Cin- 

 cinnati Island, as we may call that high land now covered with 



* See Map II. 



