of the Ohio Coal-measures. 193 



from the base of the Pittsburg to the top of the Waynesburg 

 coal. 



When the Second Geological Survey of Pennsylvania was 

 organized Mr. Franklin Piatt was engaged as Assistant Geol- 

 ogist to describe the bituminous coal fields of western Penn- 

 sylvania, and, as a result of his field work in 1874, the following 

 year he published a table of Paleozoic formations in which 

 geographical names were used for those of the Coal-measures 

 with the exception of the Upper Barren Measures. The names 

 of the formations under consideration are as follows : 



Upper Barren Measures. 

 f M. Brownsville (Washington) coal. 

 | L. Waynesburg coal. 

 Monongahela \ K. Sewickley coal. 

 I J. Redstone coal. 

 [ I. Pittsburg coal. 



Conemaugh \ Middle Barren Measures. 

 & ( Mahonmg sandstone. 



E. Upper Freeport coal. 



Freeport limestone. 

 D. Lower Freeport coal. 

 Freeport sandstone. 

 Allegheny \ C. Kittanning coal. 



B' Ferriferous coal. 

 Ferriferous limestone. 

 B. Clarion coal. 

 A. Brookville coal. 



Conglomerate No. XII, (Serai).* 



It will be seen from the above that the Allegheny formation 

 extended from the base of the Brookville coal to the top of 

 the Upper Freeport coal ; the Conemaugh formation from the 

 last mentioned horizon to the base of the Pittsburg coal, and 

 the limits of the Monongahela formation differed from those 

 of the Upper Coal-measures of Rogers in that they extended 

 from the base of the Pittsburg coal to the top of the Wash- 

 ington coal, or the one succeeding the Waynesburg coal. 

 The important point in connection with this classification is 

 that geographical names were used for the three formations 

 which compose the Coal-measures proper of Pennsylvania, 

 and the terms based upon the presence or absence of valuable 

 beds of coal abandoned, so that the classification was brought 

 into harmony with the names used for the older Paleozoic for- 

 mations. Modifications of this classification were published 

 later by Prattf and in 1877 he used the name Monongahela 



* Second Geol. Surv. Penna., H, 1815, p. 8. 



f Ibid., L, 1876, pp. 12, 17, 23; and H 2 , 1877, pp. xxiii, xxiv. 



