1874.] 183 Whittlesey. 



November 18, 1874. 



Vice-President S. H. Scudder in the chair. Sixty-eight 

 persons present. 



The following papers were presented : — 



Coal Seam No. -6, Ohio Geology. By Col. C. Whittlesey. 



According to the Report of 1870, which contains the latest inform- 

 ation yet published on the general structure of the coal-bearing 

 strata of Northeastern Ohio, Coal Seam No. 6 is the most persistent 

 of the series. It is represented as having been traced through the 

 counties of Holmes, Tuscarawas, Coshocton, Carroll, and Columbi- 

 ana, covering nearly all that part of the Ohio coal field north of the 

 Pan Handle railway. On page 15 a general view of the physical 

 structure of this district may be found in the following paragraph. 



" We have learned that instead of one symmetrical basin with a 

 tolerably uniform dip to the southeast, our coal measures form several 

 troughs, in a general way parallel with the axis of the great one, of 

 which they are parts." 



In subsequent parts of the Report this discovery is dwelt upon at 

 length, as a prominent feature of the survey, particularly as account- 

 ing for the frequent disappearance and reappearance of Seam No. 6. 



Investigations previous to the Survey of 1869, tended to show that 

 the regularity of the coal bearing strata of Northeastern Ohio had 

 been over-rated. It had become evident that coal beds could not 

 safely be identified at points widely asunder, by means of their fossils 

 or their associated strata. As soon as it was found that profiles made 

 in different parts of the field did not show the same number of seams, 

 it was evident that all the beds could not be persistent. It had been 

 settled that with all the seams, sometimes within very short distances, 

 there were radical changes of the associated rocks. The coal seams 

 also change rapidly in appearance, thickness, and quality. 



These perplexing facts are presumed to have been harmonized by 

 adopting a theory of undulations. On this hypothesis, if it is true, 

 there must be as many instances of counter or reverse, dip, as there 

 are waves in the strata. If the troughs are a part of the folds of the 

 Alleghany flexures, dying out westwardly, the axes of both the syncli- 

 nals and anticlinals must be in general parallel with the crests of the 

 system in Pennsylvania. 



