588 . COAL MEASURES OF MARYLAND 



present in all the sections described and is as well developed in Mary- 

 land as elsewhere. The Brush Creek fauna is less profuse than the 

 Ames, but is clearly traceable throughout the area by means of its diai^- 

 nostic sj^ecies. The Cambridge fauna, though more meager than the. 

 Ames and Brush Creek, is probably present throughout the region, being 

 represented by brackish water forms in the eastern sections, with which 

 are associated an increasing percentage of marine species farther west. 



The lithologA" exhibits a definite sequence, which can be recognized 

 and traced through all the sections. Four coals are present. Two of 

 these, the Harlem, underlying the Ames marine limestone, and the Brush 

 Creek, beneath the Brush Creek marine limestone, are found in most of 

 the sections described from Ohio to Maryland. Two other coals, lying 

 between the Saltsburg and Buffalo sandstones, are widely distributed 

 though less persistent, being found in Ohio, at Freeport, Pennsylvania, 

 and in Maryland. Two non-marine limestones are present. The upper 

 of these, the Ewing, ]>eing widely distributed beneath the Harlem coal,. 

 at many localities from Ohio to Maryland. Among the most signifi- 

 cant features of the section are the red beds. The Pittsburgh red shale 

 is very persistent, occurring a short distance beneath the Harlem coal 

 in nearly every section described, while the Meyersdale red shale i? 

 observable at many localities east of Pittsburgh. The Saltsburg and 

 Buffalo sandstones are also important and persistent members of the 

 sections described. 



The columnar sections show that the members occur at intervals which 

 vary systematically throughout the area. Beginning with an interval 

 of 145 feet between the Harlem and Brush Creek coals, in the western 

 section, the distance between these beds increases systematically from 

 west to ea^t until, in the Georges Creek Valley, it is 260 feet. 



This systematic change is well shown by the columnar sections, in 

 which the sections are placed on an east and west line. The intervals 

 between the Harlem and Brush Creek coals are remarkably similar in 

 the last three sections, being, as shown by the diamond-drill cores, 261 

 feet in the Somerset basin, 260 feet in the Castleman basin, and 257 

 feet in the Georges Creek basin. 



Finallv. the sections are close to each other, the distance from th'j 

 Georges Creek basin to the Castleman basin being 10 miles: from tiie 

 latter to the Somerset section 15 miles: from the Somerset section to 

 Latrobe 25 miles: from Latrobe to Pittsburgh 30 miles: from Pittsburgh 

 to Freeport 25 miles. The sections at Latrobe, Pittsburgh, and Free- 



