350 The American Geologist. •^""''' ^■"'■'' 
along- the creek south of AFount W'ashingion, the thickness of 
the Richmond is apparentl\- the same as at Floyds Fork, name- 
ly about 69 feet. However, between Mount Washington (69 
feet) and the William McGrudor locality (32 feet), north of 
Cane spring, in the southeastern part of Bullitt county, a I'is- 
tance of 8 miles, the average rate of diminution is about 4.6 
feet per mile. The thinnest ' section of the Richmond, so far 
discovered in Kentucky, is located along the road leading- 
southwest from Balltown. Here the Richmond is only 22 feet 
thick, indicating an average diminution in thickness, in the 
13 miles south of the McGrudor locality, of about .8 foot per 
mile. 
The Middle and Lozi'cr Richmond. 
The thickness of the richly fossiliferous clays and thin 
limestones, at the base of the Richmond stage, appears to be 
about the same at the crossing of the Louisville-Bardstcwn 
pike over Floyds Fork, and south of Mount Washington, as at 
the mouth of Bull creek, namely, between twenty-five and 
thirty feet. This suggests that the lower, richly fossiliferous 
part of the Richmond section at these localities includes both 
Lower and Middle Richmond strata. No attempt has been 
made as vet to distinguish between them. Strophomena ni- 
gosa occurs in the lower part of the Richmond section at 
Floyds Fork. Hchertclla occidentalis has been found at the 
top of the richly fossiliferous section at Mount Washington. 
Within a distance of four or five miles southwest of Mount 
Washington, the very fossiliferous part at the base of the Rich- 
mond is reduced to about fifteen feet, and about eight miles 
south of Mount Washington, at the William JMcGruclor local- 
ity, in the southeastern part of Bullitt county, its thickness is 
only five- or six feet. Farther south, in Nelson and Marion 
counties, the richly fossiliferous part at the base of the Rich- 
mond varies between six and eleven feet. 
It is possible that the sudden decrease in thickness of the 
richly fossiliferous part of the Richmond stage between Mount 
Washington and the William AlcGrudor locality is accompan- 
ied by the disappearance of the Lower Richmond. The evi- 
dence is not conclusive. ~\lost of the fossils found in 
this richly fossiliferous part of the section at the William 
McGrudor locality, and at the numerous localities in Nel- 
