456 STEVENSON— THE FORMATION OF COAL BEDS. L-\ov. i. 



line. Whether or not they extended across Tennessee into Alabama 

 cannot be determined by the stratigrapher. the palseobotanist nnist 

 answer the question ; but one can hardly resist the a priori conclu- 

 sion, whatever that may be worth, that the Pocahontas did extend 

 across Alabama and around to the southwestern outlet, as no outlet 

 westward for the waters of the eastern valley appears in X'irginia 

 and Tennessee, and there seems to be not the slightest reason for 

 supposing an eastern outlet anywhere to the Atlantic. The New 

 River area is much greater, embracing the southern and middle 

 anthracite fields at the north, where the western limit is well defined. 

 In the bituminous region, the eastern outcrop is continuous from the 

 northern limit in West Virginia into Alabama, where the formation 

 is recognizable throughout the whole field ; northward, on the west- 

 erly side of Alleghania, it occupies a broad area to the northern 

 border of Kentucky whence it extends in a narrow strip almost to 

 Lake Erie. The Beaver, at its close, evidently covered the whole 

 basin from the northern border southward to central Tennessee ; 

 beyond that line it has been removed by erosion for about 75 miles 

 and it is not reached again until one is well south from the northern 

 line of Alabama. The stratigrapher cannot make correlation of 

 horizons there, but the presence of Beaver seems established beyond 

 doubt. 



The formations of the Athens are recognizable in the anthracite 

 fields as well as throughout the bituminous region southward into 

 Kentucky and West Virginia ; how extensively they were repre- 

 sented in Tennessee is undetermined. The Wheeling and Dunkard 

 deposits, of less original extent and confined to the northern part of 

 the bituminous region, can be studied not only by means of the many 

 recorded exposed sections, but also by means of many hundreds of 

 oil-well records, which make clear the conditions as they existed 

 in the deeper portions of the region. 



The Sandstones. — Stratigraphers have asserted many times that 

 sandstones are of very little worth as horizons. It is true that those 

 deposits exhibit abrupt changes in structure and composition, both 

 laterally and vertically ; and it is equally true that, in not a few 



