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The Mount Carmel Fault. 



William N. Logan — Indiana University. 



Early in the fall of 1916 the attention of the writer was attracted 

 to a reversal of dip in some beds of limestone lying in eastern part of 

 Monroe County. In places this reversal of dip was noticeable in the 

 limestones which overlie the Knobstone shales and sandstones, in other 

 places in the sandstones of the Knobstone and again in beds of lime- 

 stone occupying certain horizons in the Knobstone. Upon an investiga- 

 tion of the available geological literature I found in the Report of the 

 State Geologist for 1893, pages 390-91, that Siebenthal discusses the 

 Heltonville Limestone Strip as follows: "Commencing at Limestone 

 Hill, eight miles southeast of Bloomington and extending east of south- 

 east through Heltonville to, and probably beyond. Fort Ritner, Law- 

 rence County, is a band of limestone from one-half to one and a half 

 miles in width, bordered sharply, both east and Vv^est, by Knobstone, and 

 known in that neighborhood as the Limestone Sti'ip. Isolated patches 

 of similar limestone occur north of this strip and in line with it. The 

 strip is well developed in the vicinity of Heltonville, Lawrence County, 

 where it gives exposures of the Harrodsburg, Bedford Oolitic and Mit- 

 chell limestones." 



At many points the Knobstone contains intercalated lenticular beds 

 of limestone, and it is possibly conceivable that the conditions which 

 prevailed while these beds were being deposited might have been ex- 

 tended over a narrow territory like the Heltonville strip. However, the 

 fact, first, that Knobstone has not been found overlying this limestone, 

 and second, that it shows the lithological facies of the Harrodsburg, 

 the Bedford Oolitic and the Mitchell limestones, and the faunas of these 

 formations, identifies it with them, and shows conclusively that it is a 

 nari'ow band of these formations, occupying a depression in the Knob- 

 stone, and not an incliided member of the Knobstone. 



This depression may have resulted from a double fault or may be 

 an old erosion channel. Some things seem to point to one as the origin 

 and some to the other. The facts at hand incline us to the latter view. 



