574 COAL MEASURES OF ^tAEYLAXD 



Mayuadier coal — Upper Bakerstowu coal. 



Albright limestone. 



Friendsville black shale and fauna — Cambridge fauna ? 



Thomas coal — Lower Bakerstown coal. 



Meyersdale red shale. 



Buffalo sandstone. 



Brush Creek rider coal. 



Brush Creek limestone, shale, and fauna. 



Brush Creek coal. 



Irondale limestone. 



Corinth sandstone. 



Thornton clay, upper bench. 



Mahoning red shale. 



Gallitzin coal. 



Thornton clay, lower bench. 



Mahoning limestone. 



Upper Mahoning sandstone — massive. 



Piedmont coal. 



Lower Mahoning sandstone — massive. 



Faunas. — Among the most conspicuous features of the Conemaugh 

 formation of Maryland are three marine faunas termed the Brush Creek, 

 Friendsville (Cambridge ?). and Ames in the above list. The Brush 

 Creek limestone and shale contain a rich fauna, including many Chonetes 

 verneuilianus, Bulimorplia nitidula, etcetera. The Ames limestone forms 

 lenticular nodules in black shale, both shale and limestone abounding in 

 fossils, including Amhoccelia planoconvexa, Chonetes granulifer (typical 

 form), and Derhya crassa. Shells of these three species constitute a 

 large part of the limestone at many places. Associated with them are 

 many other species. 



The Friendsyille shale bears a meager fauna (Cambridge fauna ?) 

 in the Georges Creek Valley, where it has a brackish water aspect. It 

 contains an increasing number of marine species westward, where it 

 includes Productus cora, PusfuJa nelrasl-ensis, Derlija crassa, et<}etera. 



A fourth fauna is found a short distance above the Lower Brush 

 Creek fauna, in the western sections, where it contains Spirifer camera- 

 tus, Chonetes venieuilianus, Productus cora, etcetera. It appears to 

 occupy the position of the Upper Brush Creek fauna of Ohio. 



MOyrjyGAHELA FORMATIOX 



Character and thickness. — This formation consists of interbedded 

 shale, sandstone, and limestone and contains a number of important 

 seams of coal, including the great Pittsburgh seam. As defined in the 



