COAL FIELDS. 279 



outcrops that no geologist could be pardoned for losing for a single mile, 

 if allowed to connect his series step by step, the seam can be followed 

 from the Pennsylvania state line in the Ohio valley, where it is known as 

 the block coal, through the Yellow Creek valley, where it is called, the 

 Hammondsville strip vein, under the divide that separates Tuscarawas 

 water from Yellow Creek, to the Little Sandy, where it is universally 

 known as number 6. Eastward from this point, it is extensively worked 

 in Stark count}-, and is also present everywhere, though thin, in northern 

 Columbiana county. It can also be directly connected, with the Penn- 

 sylvania series through the Mahoning valley, as was first shown by Pro- 

 fessor I. C. White. 



Westward and southward from the Sandy Creek valley, the seam is 

 the most reliable and the best known element, as well, of the entire geo- 

 logical scale of the district traversed. No question is possible as to its 

 extension and continuity from the Tuscarawas valley to the Ohio River. 



This is the lowest of the coal seams, the outcrops of which have 

 been laid down on the series of maps that accompany this volume. As 

 explained under the previous head, the outline of the Middle Kittanning 

 seam answers for the Lower Kittanning seam nearly as well, the two 

 seams being separated by so small an interval. 



A study of these maps reveals large areas of the Middle Kittanning 

 seam in many counties of our Coal Measures. These facts will be treated 

 under a subsequent head. 



The Middle Kittanning seam does not promise to support deep 

 mines to any great extent in Ohio. It is emphatically a marginal deposit, 

 in the order of its formation. 



The Freeport Group. 



The two coal seams of the group next reached are the counterparts 

 in many ways of the group last passed in review, namely, the Kittanning 

 coals. While three seams are recognized in the Freeport group in Penn- 

 sylvania, but two are found in Ohio, viz., the Lower and the Upper. 

 Again, as in the Kittanning group, the principal value belongs to the 

 uppermost of the two seams, so far as Ohio is concerned. The Upper 

 Freeport seam, as has been already stated, is beyond question one of the 

 three leading seams of our coal field. For the present, the Middle Kit- 

 tanning seam is much more productive than the Upper Freeport, largely 

 through the contributions of the Hocking valley field, but in the course 

 of a generation or two, the table will be completely turned. The facts 

 pertaining to this point will be presented on a later page, in connection 

 with a description of the maps. 



5. The Lower Freeport Coal. Coal No. 6a. The Lower Freeport 

 seam supports but one important coal field in the state, namely, the 

 Steubenville field. At no other point does it attain importance enough 

 to warrant mining in the large way at the present time. From large 

 areas where it is due, it is altogether wanting, at least in any econom- 



