124 



Kindle — Unconformity at the Base of the 



The most striking examples of pre-Chattanooga erosion in 

 the Devonian limestone which have been observed occur 

 at Irvine, Ky. A considerable exposure along the railway 

 west of town shows the contact of the Chattanooga shale 

 and the Devonian limestone to be, as it often is, a horizontal 

 line with no intervening residuary clay and no departure 

 from exact parallelism of the adjacent formations. Foerste* 

 has published photographs illustrating this type of the contact 

 elsewhere in Kentucky. Near town, however, this apparent 



Fig. 2. 



Fig. 2. Chattanooga shale and Devonian limestone -unconformity at 

 Irvine, Kentucky. The Chattanooga shale is marked A, and the Devonian 

 limestone B. 



conformity of the two formations terminates abruptly, and we 

 find the black shale resting for several yards on a highly irreg- 

 ular surface of the Devonian limestone, and on one side of the 

 section abutting against a vertical wall of limestone about 8 feet 

 in height. The general relations of the two formations at this 

 point are shown in the photograph fig. 2. The beds marked 

 &> 5kare a nearly pure limestone of Onondaga age. Those marked 

 A ^ are the basal beds of the Chattanooga shale, which at this 

 horizon includes some dark magnesian and silicious beds inter- 

 bedded with black shale. In the illustration the hammer 

 rests upon the side of the limestone ledge and the hand of 

 the man upon the shale. The details of this vertical contact 

 * Kentucky Geol. Surv. Bull. No. 7, figs. 8, 9, 1906. 



