I9I2.] STEVENSON— THE FORMATION OF COAL BEDS. 481 



others ; isolated deposits are reported from 9 counties of Pennsyl- 

 vania and from 6 in Ohio but there seems to be very little in the 

 greater part of West Virginia. The total area of the reds during the 

 later Conemaugh at any one time was less than 1,000 square miles 

 and the deposits are widely separated. At the same time, one must 

 note carefully that, while the deposits are usually of small superficial 

 extent, yet the thickness of some is important. 



The conditions during the Monongahela were much like those 

 at the end of the Conemaugh but the area in which deposits were 

 made is much less. No red is reported from Pennsylvania except 

 a thin streak at one locality, nor is there any in the West Virginia 

 panhandle. There is none in Ohio except near the Ohio River toward 

 the Central area. But, as one approaches that area, the red increases 

 and some of the beds are important. In West Virginia, there seems 

 to be very little along the eastern side north from the Kanawha 

 River and in the interior the occurrences are few and irregular until 

 one comes to the Central area, where beds are many but more irreg- 

 ular than at any time during the Conemaugh. In Ritchie county, 

 every foot of the section for 300 feet above the Pittsburgh coal bed 

 is marked by red shale in some well or another ; but that statement 

 tells little respecting the conditions. The beds vary from 7 to no 

 feet as measured in different records ; in some borings, one finds 

 220 feet of red in a vertical distance of 300 feet, while in others 

 near by the total is less than 100 feet. Similar variations are found 

 in other counties but the maximum thickness is less. Aside from the 

 insignificant and distant patches in Pennsylvania and Ohio, the area 

 in which reds were deposited at various times during the Mononga- 

 hela is less than 4,000 square miles and no deposit has great super- 

 ficial extent. 



During the Washington, local conditions favoring deposition of 

 reds existed here and there in a much greater area ; but the condi- 

 tions were local. Reds are reported from three localities in Wash- 

 ington and two in Greene county of Pennsylvania ; from six in Ohio; 

 from a number of places in northern West Virginia ; but these are 

 all far apart and the most of them are insignificant. Only when one 

 reaches the Central area does he find the deposits assuming impor- 

 tance. Even there the occurrence is indefinite ; a boring in Wood 



