225 



Paleozoic Era when the Appalachian revolution which resulted in the 

 elevation of the eastern part of North America took place. Contem- 

 poraneous with or subsequent to that great epeirogenic movement, fault- 

 ing and minor folding took place in Indiana, Illinois and Iowa, and 

 other States lying as far west as these from the region of maximum 

 disturbance. These faults like the one under discussion have a north- 

 west trend. 



The Heltonville Fmilt. — About one mile west of the Mt. Carmel fault 

 there is a second fault. This I have named the Heltonville fault be- 

 cause the rift is exposed a short distance east of Heltonville in the bed 

 of the north fork of Leatherwood Creek, at a point just east of the 

 wagon crossing under the Southern Indiana railroad. This fault lies ap- 

 proximately parallel with the Mt. Carmel fault. The limestone has been 

 faulted down against the Knobstone. Slickenslides have been produced in 

 the limestone and it has been much fractured. In places the limestone 

 has been thrust backward and fragments of the Knobstone shales have 

 been thrust into the limestone. In places these formations are dove- 

 tailed, fingers of limestone projecting into the Knobstone and vice versa 

 as first one and then the other yielded to the pressure. The fragments 

 of limestone containing inclusions of shale have been united by calcite 

 veins. 



Though the fault character of the disturbance at this point is in- 

 contestable it is not equally clear at other points. The disturbance ex- 

 tends both north and south of this point, but it probably passes into a 

 fold in both directions. In Monroe County near Unionville there is an 

 anticline which occupies about the same position in relation to the Mt. 

 Carmel fault as the Heltonville fault does. Similar folds have been 

 noted at intervening points and also to the south of Heltonville. 



Effect Upon Topography. — The general effect upon topographic 

 conditions within the area of disturbance has been to produce a nar- 

 row limestone belt extending parallel with the main Knobstone outcrop 

 and bordered on each side by outcrops of Knobstone. In the southern 

 portion of the faulted area the western belt of Knobstone is absent, but 

 its nearness to the surface along the line of the eastward reversal of 

 dip is revealed in the channels of many streams which have carved 

 their valleys at right angles to the line of reversal. Probably the most 

 marked effect is on the drainage. Both surface and underground 



15—11994 



