CORRELATION OF CONEMAUGH FORMATION 157 



but it seems to be wanting in Kentucky, though it may be represented by 

 Coal 12. The Barton coal is rarely of economic importance. 



The Anderson coal bed of E. B. Andrews (Norwich of northern 

 Guernsey, Ohio) has been taken for the Barton (Bakerstown) in some 

 portions of Pennsylvania and West A 7 irginia. It seems to be wanting on 

 the east side of the basin, the most easterly locality being in southern 

 Butler of Pennsylvania; thence to the Ohio line it is utterly insignificant. 

 It becomes distinct in Brooke county of northern West Mrginia, whence 

 through Ohio it is persistent into Kentucky, where it is the Coal 11. It 

 is a few inches to 15 feet above the Cambridge limestone in Ohio, but 

 the interval increases to between 30 and 40 feet in Kentucky. The bed is 

 of economic value in only a small area within central Ohio. 



The Cambridge limestone of E. B. Andrews (Pine creek of western 

 Pennsylvania) is probably the same with a limestone at about 50 feet 

 below the Ames in the second bituminous basin of Pennsylvania as well as 

 in northern West Virginia just west from Chestnut hill and in western 

 Maryland; but it is first clearly recognizable along the northern outcrop 

 in Armstrong county of Pennsylvania, where in many respects it re- 

 sembles the Ames. Its occurrence as far as Beaver county is a little irregu- 

 lar, but thence along the western outcrop through Ohio into Kentucky it 

 is as persistent as the Ames. The interval between these limestones varies 

 from 90 to 130 feet along the northern and western outcrops. The 

 Cambridge limestone is present at the southwest corner of West Virginia, 

 but it seems to be wanting under the Cowrun anticline, even in Wash- 

 ington county of Ohio. It is persistent only on the west side of the 

 basin, the occurrence on the east side being very irregular. The bed is 

 much more variable than the Ames. In Pennsylvania the color is from 

 dark to gray; in northern Ohio from gray to blue and often weathers 

 buff; while farther south it is a dark limestone associated with dark 

 shales ; yet in some portions of southern Ohio it is the "White f ossifer- 

 ous" limestone. In Noble county of Ohio a new limestone appears di- 

 rectly over the Anderson coal bed, and thence southward there are two 

 Cambridge limestones, 10 to 30 feet apart, designated as Upper and Lower 

 by Professor Edward Orton, one or the other being absent at times for 

 several miles. The Lower is the Cambridge limestone proper, equivalent 

 to Doctor I. C. White's Pine creek. Unlike the Ames, both beds tend 

 to be cherty toward the south. In Kentucky the interval between the 

 Cambridge limestones increases to about 50 feet, with the Anderson at 

 about one-third of distance below the Upper. This limestone carries a rich 

 marine fauna in Ohio and western Pennsylvania, as also in West Vir- 

 ginia at many places north from the Baltimore and Ohio railroad and 



