252 JOHN F. NEWSOM 



to the west becomes more gently rolling, and the low hills are 

 made up of black shale covered over in most cases by glacial 

 material. 



The Devonian black shale outcrops over a strip of country 

 some twelve miles wide. Except at its eastern edge where it 

 has been eroded to a feather edge, and where the underlying 

 limestone controls the topography, it forms very low hills, and 

 often almost flat plains. The black shale passes beneath the 

 drainage near Scottsburg. In a deep well drilled at Scottsburg 

 its thickness was found to be 120 feet. 



The eastern lowland. — Overlying the Devonian black shale is 

 the Knobstone group of clay shales, sandy shales, and sand- 

 stones. The lower limit of this group is marked by the Rock- 

 ford Goniatite limestone, which, owing to its thinness has but 

 little effect on the topography. The lowest beds of the Knob- 

 stone group are made up of clay shales. These clay shales, with 

 the underlying Devonian black shale, are directly responsible 

 for the low country and very gentle topography to be found 

 throughout southern Indiana, between the high escarpment 

 known as the Knobs, and the deep gorge of the Ohio River. 

 The western part of this region may be properly styled the east- 

 ern lowland. 



One noticeable feature of the topography from the top of 

 the escarpment near Hanover, where the elevation is 800 feet 

 above tide, to Scottsburg (570 feet above tide), is the gradual 

 westward slope of the country, corresponding almost exactly to 

 the average dip of the strata. The tops of the low hills of this 

 region are all found in approximately the same slightly west- 

 ward dipping plain. 



The "Knobs" and the middle plateau. — The Knobs form by 

 far the most important topographic feature in the eastern part 

 of the extreme southern portion of Indiana. They are made up 

 of Carboniferous strata belonging to the " Knobstone group" 

 with its capping Carboniferous limestones. The Knobs do not 

 form a range of hills, properly speaking, but are rather a high 

 escarpment, generally facing eastward, with a plateau sloping 



