West of the Alleghany Mountains. 



247 



to sixty feet at York. Under these circumstances I am 

 inclined to look upon the thin coal, one hundred feet above 

 Coal VIII at Knoxville as XI and not X. Thinning out 

 northward, like the lower coals, as these beds do, and grad- 

 ually uearing Goal YIII, it is more than probable that they 

 in like manner were successively merged into Coal VIII, 

 which I regard as the parent bed of all the upper coals in 

 Ohio, remaiuiiig in existence as a flourishing swamp from 

 the beginning of the epoch until its close. 



A similar condition seems to have existed on the eastern 

 shore of the inland sea, though it is somewhat difiicult to 

 obtain thoroughly satisfactory evidence, owing to the pecu- 

 liar manner in which information is scattered through the 

 Pennsylvania report. Three short sections have been taken 

 from that report, one from each of the three basins south of 

 the Ohio. 



CONDITIONS DURING DEPOSITION OF THE UPPER 

 COAL MEASURES. 



To many it may appear that the data presented in this 

 paper are insufficient to justify generalization respecting the 

 conditions prevailing during the epoch of the upper coal 

 measures. But let it be remembered that the portion of the 

 field examined is by far the most important economically 

 and by far the most satisfactory in the exhibition of details. 



