224 



other minerals are present in some parts of the brecciated zone, but 

 there is an absence of the more insoluble minerals, such as silica or the 

 silicates. This fact leads to the conclusion that meteoric rather than 

 thermal waters have played the leading role in the concentration of 

 these minerals. 



Periods of Movement. — The question of whether the displacement 

 took place all at one time or was intermittent is an interesting one. All 

 of my attempts to find an evidence of intermittent movement by an ex- 

 amination of surface features have been unsuccessful. If there wei'e 

 intermittent movements of any considerable extent we would probably 

 find them revealed in hanging valleys on the upthrow side and the rapid 

 broadening of valleys on the downthrow side of the fault. In case there 

 were two stages of movement, and the movement in the last stage an 

 exceedingly slow one, the vertical cutting of the main stream might 

 be as rapid as the uplift, but still the rejuvenation of the tributaries 

 should result in a narrowing of the valleys. In the rift zone there is 

 evidence of two stages of movement though the amount of displacement 

 in the second stage is slight. The time interval between the two move- 

 ments was of considerable length, since the fragments of the brecciated 

 zone were firmly cemented befoi-e the second movement took place. 

 Fragments of shale which were included in the limestone fragments 

 during the first movement were faulted by the second movement. These 

 shale inclusions would not have undergone faulting had they not been 

 held rigidly in place by the cementing material. 



Amount of Throw. — The amount of throw of the fault varies prob- 

 ably from 200 to 300 feet. Opportunities for measuring the amount of 

 throw are not numerous. It can best be computed by estimating the 

 total amount of eastward dip of the formations along the line of con- 

 tact between the Harrodsburg and the Knobstone. At a point south 

 of Mt. Carmel the difference in elevation of the contact above sea level 

 is 50 feet in a distance of one-fourth mile. Since the width of the 

 down-thrown block is at least one mile and a half in this locality the 

 throw of the fault is at least oOO feet. The amount of dip of the down- 

 thrown beds in other localities is less than at this point, so much less 

 that the indicated throw is not moi'e than 200 feet. 



Age of the Fault. — The time at which the dislocation occurred can 

 not be fixed definitely. It is probable that it occurred at the close of the 



