GENERAL GEOLOGY OF 0LAYSY1LLE QUADRANGLE. 
49 
tion, the Upper \\ ashington limestone and Washington coal of the 
Washington formation, and the Waynesburg coal of the Mononga- 
hela are easily recognized and widespread in outcrop. These beds 
have furnished most of the data from which the surface structure 
was determined, and for this reason are the only ones mentioned 
below. A detailed description of all the rocks showing at the sur¬ 
face is given in Part II of this paper (pp. 149-175). 
KEY ROCK AND INTERVALS TO IMPORTANT BEDS. 
The Upper Washington limestone marks the top of the Washing¬ 
ton formation. It is a thick and very persistent limestone bed, hav¬ 
ing two or three characteristic milk-white layers near the top that 
render its identification easy over a large portion of the Claysville 
quadrangle. For this reason, and also because it shows in outcrop 
over a greater area than any other bed in the southern portion of the 
quadrangle, it has been selected as the key horizon from which the 
structure of the surface rocks is mapped. This limestone is well 
exposed along the sides of the valleys of the larger streams in the 
townships of Morris, North and South Franklin, East and West 
Finley, and the southern portions of Donegal, Buffalo, and Canton. 
To the north of the Baltimore and Ohio Railroad it is well up 
toward the tops of the hills, and in Independence and Hopewell 
townships it is present only in the highest hills. In Cliartiers town¬ 
ship the bed is entirely absent. 
The Claysville and Prosperity limestones outcrop in more or less 
isolated patches along the tops of the high ridges of East and West 
Finley, North and South Franklin, and both Morris townships. 
Owing to the pronounced dip of the rocks over the small area in 
which these beds are exposed and the great horizontal distance be¬ 
tween their outcrops and that of the Upper Washington limestone, 
it is not possible to determine accurately the vertical distance or inter¬ 
vals between them. At only seven places in the quadrangle were the 
intervals between the Upper Washington limestone and these beds 
obtained with a degree of accuracy worth recording. These meas¬ 
urements shoAv the Claysville limestone to be from 185 to 221 feet 
(mean, 203) and the Prosperity from 101 to 115 feet (mean, 108) 
above the key rock. In several places these beds have been of great 
value in determining the direction and amount of dip of the rocks. 
The Washington is the most conspicuous bed of coal in the Clays¬ 
ville quadrangle. It is entirely under cover in the townships of 
East and West Finley, Morris, and South Franklin, but is well 
exposed in North Franklin, Canton, Hopewell, Blaine, Buffalo, Done¬ 
gal, Independence, and portions of Cross Creek and Mount Pleasant 
3496—Bull. 318—07-4 
