FAULTING IX NORTH-CENTRAL KENTUCKY 103 



suspected was the relation in the former instance between the oil and the 

 monoclinal structure and the monoclinal structure and the fault. Later a 

 shallow oil pool was developed at the southwestern end of the Glencairn fault, 

 near Irvine. 



The oil horizon in the first two instances appears to be a magnesian lime- 

 stone of approximately Clinton (Brassfield) age. In the Irvine wells the oil 

 appears to come from the Columbus (Devonian) limestone. 



In the Lexington limestone of the Blue-grass region are barite veins which 

 have been rather extensively worked in recent years. They are in evident 

 relation to the faults, being fillings of solution cavities, which are widened 

 cracks usually extending outward from the faults at approximately right 

 angles. The walls show no signs of any considerable vertical displacements, 

 but there is some evidence of horizontal movements. 



All this fissuring and faulting appears to be of the same age, which is post- 

 Pennsylvanian, as Pennsylvanian strata are traversed and displaced by some 

 of them. 



It is also evidently pre-Tertiary. The latter conclusion is reached from a 

 study of the relations of the Kentucky River to its fault. 



The Kentucky appears to be a superimposed river which formerly crossed 

 a baseleveled Cincinnati arch in a northwesterly direction from the present 

 site of Boonesboro to where Elkhorn Creek now empties into it. This would 

 carry it by the present site of Lexington. 



As the river during a subsequent period of rejuvenation cut its way deeper 

 into the strata, it came more and more under the influence of the fault, the 

 effect of which was to cause it to veer in its course to the southwest. 



The excellent illustrations of intrenched meanders in this portion of its 

 course, as in other portions, would seem to indicate that the diversion was 

 before any of the present meanders were acquired. 



These meanders are supposed to date from a period of Tertiary baseleveling. 

 hence the Kentucky River fault, and apparently all the other faulting as well, 

 is pre-Tertiary. 



We have independent evidence that the Cincinnati Geanticline was first 

 formed in late Silurian or early Devonian time (researches of Foerste). It 

 appears to have received a second bowing up after the aggradation period of 

 the Pennsylvanian, which followed the complete peneplanation just before the 

 latter period was ushered in. 



Provisionally we may assign this faulting to the post-Pennsylvanian revo- 

 lution. 



Though now only the eastern end of the faults traverse and displace Penn- 

 sylvanian strata, there is strong evidence from outliers scattered out over the 

 Blue-grass region that the strata from the Ordovician up to and inclusive of 

 the Pennsylvanian — except very uppermost Silurian and lowermost Devonian — 

 once went over the Cincinnati arch. 



The recentness of the strata preserved in these faulted outliers is generally 

 proportional to the amount of the throw in the faults and the distance they 

 are situated from the axis of the arch. 



One very instructive example is Burdetts Knob, near the southern end of 

 the Kentucky River fault, almost on the summit of the central anticlinal dome. 

 Here is preserved a little patch of Lower Mississippian. 



