Heating op a diki^ectiuc in a condenser — I'reliminary note. By Albeki 

 P. Carman. 



PrELIMINAHY notes on the (4E0L0GY OF DeAUHORN county. By A. .1. BlONEY. 



The geological formations in Dearborn county are the lower Silurian 

 which is found in almost every part of the county, the upper silurian occu- 

 pying only a small area in the northwest part of the county and the glacial 

 deposit of the post-tertiary times. Blue limestone is the characteristic rock. 

 The rock is abundantly supplied with fossils, much of it being composed 

 almost entirely of brachiopods, corals and other closely related fossils. On 

 this account they are of little value for building purposes, the chief use be- 

 ing for foundation stones. Some of the hardest will weather very percep- 

 tibly in only a few years. Along the railroad at Moore's Hill, the rocks are 

 so easily disintegrated that the cliflFs appear more like immense shell banks 

 than true rocks. 



In the northern part of the county, near the upper silurian outcrop, the 

 rock is much harder and is quarried in considerable quantities, and is re- 

 garded as a very fine quality of stone. It, however, is not equal to that 

 which is found in Ripley and Decatur counties. Where there is no drift 

 the soil is marly — that is, composed of lime, clay, sand, etc. In the greater 

 part of the county and especially in the western section there is much clay ; 

 on the fiats this is very tenacious. In the eastern part of the county along 

 the Ohio drift deposits are very prominent. There is some drift at New- 

 town, near Lawrenceburgh, but the most important deposits are just outside 

 the county, in Ohio county, and where it is about fifty feet thick and three 

 miles below Aurora on the Kentucky side, above and below Wolper creek. 

 About five miles further to the south in Boone county, Ky., still more drift 

 is to be found. This last deposit is about on a level with the highest part 

 of the cliff, that is, 1,000 feet. The drift at the mouth of Wolper creek, 

 called Split-rock, is an immense mass of conglomerate fully 100 feet thick 

 and nearly 400 feet lower than that five miles to the south. There is one 

 perpendicular clifi" that measures 7.'^ feet high, and above this there is a rise 

 of about 20 feet more, and how deep it extends no one has investigated. 

 About one- fourth mile to the south, on the opposite side of a small creek, 

 is still more deposit and one cliff is even higher than the one just described. 



