COXCLUSIOX AXD SUMMARY 59B 



faunas in the Lfower Conemaugh having a wide distribution. Asso- 

 ciated with them are coals, red beds, fresh-water limestones, and eve a 

 sandstones, which, though lenticular and discontinuous, are found at 

 man}' places in the northern Appalachian coal basin. 



Other features are systematically variable. Thus the Conemaugh in- 

 creases in thickness eastward, being 350 feet thick in Ohio, 600 feet at 

 Pittsburgh, Pennsylvania, and 900 feet in Maryland. The deposits are 

 more arenaceous eastward, indicating steeper stream gradients there. 

 The coal content also increases eastward, seven coal seams being described 

 in the Conemaugh of Ohio, while 27 beds are found in the same limits in 

 Maryland. 



The red beds are formed at definite horizons over wide areas. They 

 are thin in the eastern sections, but increase in number and volume west- 

 ward, their development appearing to bear an inverse relation to that oi 

 the coals. Conditions favorable for the formation of red beds thus 

 appear prejudicial to the accumulation of coal. If, as their occurrence 

 suggests, they have climatic significance, they should have large value 

 for purposes of correlation. 



Certain Permian elements make their appearance associated with the 

 red beds as seen in the flora, insects,-' and the possible occurrence of a 

 Pareiasaurus in West Virginia.^^ The significance of these facts needs 

 further elucidation. 



The' accumulation of the sediments seems to indicate progressive 

 crustal deformation with downwarp toward the east. If coal beds are 

 laid down near sealevel, the conditions would appear to have been rather 

 stable over large areas until Brush Creek time, after which, as shown 

 by the wedgeUke thickening of the Conemaugh eastward, warping be- 

 came more marked, reaching a maximum before the deposition of the 

 Pittsburgh seam. 



The preceding discussion may be summarized briefly as follows : 



1. A persistent series of beds containing marine faunas is recognized 

 in the lower Conemaugh. Its faunas, lithology, sequence, and intervals 

 are described. 



2. This series is traced by means of numerous sections from Ohio to 

 Maryland, thus laying a basis for the correlation of the middle Coal 

 Measures of this area. 



27 Samuel H, Scudder : Bull. U. S. Geol. Survey, No. 124, p. 12. 



28 E. C. Case : W. Va. Geol. Survey. Report on geology of Braxton and Clay coun- 

 ties, 1917, pp. 817-821. See also I. C. White, ibid., pp. 822-829, and E. C. Case, Ann. 

 Carnegie Mus., vol. iv, 1908, pp. 234-241. 



