NO. 1814 NETTELROTH FOSSIL COLLECTION — BASSLER 125 



the Falls naturally fell to the first collector on the scene, and there 

 was therefore much rivalry among the paleontologists of the Falls 

 cities. The peculiar conditions of weathering on the Falls left all 

 of the exposed fossils silicious, so that portions still embedded in the 

 limestone had to be carefully chiselled out. This silicification ex- 

 tended a short distance into the limestone, and it was due to this fact 

 that the more delicate forms, when attached to the rocks, could be 

 etched out with acid. In figure 2, plate x, both the Devonian and 

 Silurian limestones are shown in the face of one of the old Bear 

 Grass Creek quarries. Fresh exposures of these limestones show 

 relatively few fossils, but the weathered debris and strippings of the 

 quarry are often crowded with specimens. Other well-known Niag- 

 ara localities along Bear Grass Creek are represented in figures 

 I and 2, plate xi. The Devonian black shale, or New Albany shale, 

 as it is locally known, although usually unfossiliferous, has yielded 

 a few fossils from strata above the river banks at New Albany, 

 Indiana. The youngest Paleozoic rocks in the immediate vicinity 

 of Louisville are of early Mississippian age. They include a repre- 

 sentative of the Rockford limestone, which locally separates the 

 black shale from the overlying shales and sandstones of the Knob- 

 stone group. The latter forms the upper part of the hills and is> 

 well shown at Button Mold Knob, several miles south of the city. 



The Silurian and Devonian strata of the Louisville region are 

 probably best known to the scientific world, and the accompanying 

 views are introduced to illustrate some of the localities for fossils. 



The strata at the Falls of the Ohio have often been mentioned in 

 the literature since 1827, when they were first described by Lapham. 

 The age and correlation, particularly of the Devonian strata, have 

 often been in question, although now there seems to be general 

 agreement upon the subject. 



In i860 Major Sidney S. Lyon divided the beds of the Falls, 

 according to their fossils, as follows: 



Feet 



Black slate 50 to 100 



Encrinital limestone 8 



Hydraulic limestone 20 



Spirifer cultrijtigatus bed 3 



Nucleocrinus bed 2 



Spirifer gregaria and Turbo beds id 



Coral beds 10 



Catcnipora cscharoidrs beds 40 



The Catenipora (Halysites) beds have always been recognized as 

 Silurian, being filled with fossils characteristic of that age. Recentlv 



