590 COAL MEASURES OF MAEYLAXD 



The suggested relations of the other members of the Monongahela 

 formation of Maryland are* indicated in the chapter on stratigraphy. 



Conemaugh formation'. — The Conemangh formation is distinguished 

 from the Allegheny formation by the presence of red beds, which m.ake 

 their first appearance near the base of the Conemangh and, as shown by 

 I. C. TThiter- constitute one of the most characteristic features of the 

 Gonemaugh. It is distinguished from the overlying Monongahela forma- 

 tion by the presence of marine faunas and by a lesser content of coal. 

 The top of the Conemaugh is well defined by the base of the Pittsburgh 

 seam. The lower hmit of the formation is the top of the Upper Free- 

 port coal of western Pennsylvania. 



The base of the Conemaugh has been placed, iQ the past, in the Georges 

 Creek. Upper Potomac, and Upper Youghiogheny basins of Maryland 

 and West Virginia, at the top of a coal found about 600 feet beneath the 

 Pittsburgh seam. That this is not the Upper Preeport coal is shown 

 by the fact that the Ames fauna, abounding in Amhocoslia planoconvexa, 

 Chonetes granulifer, and its other characteristic species is found buu 

 75 feet above it, while the Brush Creek fauna is found 1S5 feet beneath 

 it. Just beneath this coal is found a fauna, consisting of brackish water 

 species in the Georges Creek Valley and marine species in the wester^i 

 sections of the State, which occupies the horizon of the Cambridge Lime- 

 stone of Ohio. Eed beds occur 100 to 200 feet below the coal in ques- 

 tion. It is clear that this coal lies far above the horizon of the Upper 

 Freeport coal, apparently occupying the position of the Anderson co:il 

 of Ohio and of the upper of two coals which lie between the Saltsburg 

 and Buffalo sandstones in the section at Freeport, Pennsylvania. It, 

 therefore, can not be the Upper Freeport coal. 



The Davis coal of Maryland lies about 200 feet beneath the coal last 

 named and 120 feet beneath the Brush Creek limestone and fauna. It 

 thus occupies the position of the true Upper Freeport, which hes about 

 115 feet beneath the Brush Creek coal in the vicinity of Freeport, Penn- 

 svlvania, and is clearly traceable through the various sections from 

 Freeport. Pennsylvania, into Maryland by means of its position witli 

 respect to the critical series already discussed. The Upper Freeport 

 limestone is found in its proper position beneath this coal in the Upper 

 Potomac and Castleman basins, extending thence westward. 



The Barton coal of Maryland is not the Bakerstown, as was formerly 



- Coal Report. West Virginia Geol. Survey, vol. ii. 1903. pp. 225-227. and vol. iia. 

 1908. pp. 622-624. Report on Geology of Braxton and Clay counties. West Tirginia 

 Geol. Survey. 1917. pp. 822-829. 



