410 A. F. FOERSTE — LIMESTONES OF TENNESSEE AND KENTUCKY 



thickness of 4 feet, rests on the Waldron shale, which here varies from 

 2k to 8 feet in thickness in different parts of the quarr}^ thus giving 

 evidence of considerable unconformity within a comparatively short 

 distance. Several hundred yards from the road, at a quarry northeast 

 of that last mentioned and up a little valley, the Black shale is absent 

 and the Waverly rests on the Waldron shale, 8 feet thick. At one point 

 a few blocks of Louisville limestone intervene between the top of the 

 Waldron shale and the Waverly. A considerable distance farther east- 

 ward, a quarter of a mile west of John Scott's house (locality 8), west of 

 Whites Bend, the Black shale rests either on 2 or 3 inches of Waldron 

 shale or on the top of the Laurel limestone. Next to the Newsom locali- 

 ties the exposures near John Suell's house furnish the greatest variety 

 of Waldron fossils, but not in as great abundance. 



I Mdt 



Figure 5. — Rapid Thinning incident to Unconformity. 



The diagrams show the very rapid thinning of Silurian formations where uneonformably overlaid 



by the Devonian. 



Along the Harpeth river, between Newsom and the bridge at Pegram, 

 the Black shale is underlaid by Devonian limestone, varying from 3 to 

 12 feet in thickness, corresponding apparently to the Devonian lime- 

 stones of Kentucky and southern Indiana. The top of the limestone 

 contains fossils belonging to the horizon of the Sellersburg limestone of 

 southern Indiana and Kentucky and the Hamilton of New York. The 

 middle and lower ])art of the limestone contains Nucleocrinus verneuli, 

 a characteristic corniferous fossil. It is here called the Pegram lime- 

 stone. 



At Newsom, southwest of the station, beyond the quarry nearest the 

 railroad (locality 12), the Pegram limestone (plate 40, figures 1 and 2) 

 rests on Louisville limestone having a thickness of 32 feet, poorly ex- 



