234 
The Ohio Naturalist. 
[Vol. XIV, No. 3, 
contrasted with 71' at Laurel and 57' at Cooper’s Falls. The 
presence on Elkhorn Creek of the upper reef, S' 4" below that 
Silurian contact, shows that this thickening of strata is due to the 
more rapid accumulation of sediments toward the north. In the 
region about Camden, O., winch is as far eastward as the Saluda 
can be traced, the thickness of strata between the level of the 
lower reef and the upper reef is about 100', as nearly as the various 
exposures can be correlated. 
It is not the usual thing to have limestones and calcareous 
shales accumulating more rapidly than the more shallow water 
sands and shales, but between the limits of the lower and upper 
reefs on Elkhorn Creek the calcareous sediments accumulated over 
three times as fast as the argillaceous and arenaceous sediments 
to the north. The land evidently was so low as to suffer from 
little erosion, and the sea about it so shallow that the shifting sands 
and muds were kept stirred up by the waves when not exposed 
between tides, as shown by the ripple marks and sun cracks at 
various levels. Thus the organic accumulations here would be 
reduced to a minimum while to the north the usual favorable 
conditions would prevail. 
Of these 125' of strata on Elkhorn Creek, about 75' at the 
base are typical Whitewater sediments with the typical fauna. 
The remaining strata are 15' of barren shale at the base, with pre¬ 
dominating shales and more or less even-bedded limestones to 
the Silurian contact. These strata constitute the Elkhorn beds, 
and bear a fauna quite distinct from the Whitewater. 
The change from the Saluda sediments and fauna begins at 
Cooper’s Falls. Beneath the upper reef there are 7' of heavy 
Saluda limestones, and beneath those about 10' of thin, somewhat 
lumpy, barren shales and limestones. 
At Versailles the second reef was not seen and the sections 
studied did not run high enough to show the upper reef. But the 
10' of strata at Cooper’s Falls are represented at the top of the 
Versailles section by 9' of strata which arc much softer and more 
lumpy than at Cooper’s Falls, and they bear quite a fauna of a 
Composite Whitewater—Elkhorn type. 
Three miles north of Osgood, on Big Plum Creek and in that 
vicinity, these strata are thicker, more characteristically White- 
water at the base, then with even bedded shales and limestones 
up to the upper reef, which is 2' thick and o' beneath the Silurian. 
On a north fork of Big Salt Creek, west of Oldenburg, the 
Richmond ends with 40' of apparently fossiliferous strata. (The 
middle of this 40' is covered.) At the base are about 10' of strata 
with Rhynchotrema dentata, Strophomena sulcata, S. vetusta, 
Platystrophia laticosta, P. acutilirata, Monticulipora epidermata, 
Batostoma varians, Rhombotrypa quadrata Byssonvchia rich- 
mondensis, Ischyrodonta truncata, Conularia sp., Comulites sp.. 
