DIFFERENT PROVINCES OF NORTH AMERICA IN LATE PALEOZOIC TIME 79 



"We^ may safely conclude that the horizon of the Grape Creek flora is not 

 lower than the Freeport group on the one hand, while granting that it may on 

 the other hand, eventually be found to be at a somewhat higher stage in the as 

 yet paleobotanically unknown Conemaugh series." 



White also makes the statement that the closest afifinities with the Grape 

 Creek flora will probably be found in the lower portion of the Missourian 

 or the uppermost Des Moines: 



"The composition of the Grape Creek flora indicates a stage in the lower 

 Stephanian of the Old World. The latter division of the European Coal Measures 

 appears, in the present stage of our knowledge of the fossil floras, to correspond 

 to the Monongahela and Conemaugh series, together, perhaps, with the Freeport 

 group of the Allegheny series of the eastern United States, and to the Missourian, 

 with the upper portion of the Des Moines, of the Interior Basin." 



In Bulletin 15 of Illinois Coal Mine Investigations, Cady^ states that 

 David White concludes from floral evidence that Coal No. 6 (Grape Creek, 

 Herrin) "may be of Freeport age, possibly as high in the stratigraphic 

 column as the upper Freeport coal, which is the uppermost layer of the 

 Allegheny formation in the Appalachian region." 



In the scheme adopted by the Illinois geologists all the Pennsylvanian 

 deposits above Coal No. 6 are included in the McLeansboro formation. 

 The dividing-line between this and the underlying Carbondale formation 

 is not readily distinguished in many places, but in the light of fossil and 

 stratigraphic evidence it seems safe to consider the McLeansboro as equiva- 

 lent to the Conemaugh and higher series in Pennsylvania. 



It is to be noted, however, that little or no red shales or sandstones 

 appear in the McLeansboro formation. If this formation is equivalent to 

 the Conemaugh and higher, then the necessary conditions for the formation 

 of red beds were either never present in Illinois, or, what is more probable, 

 the conditions necessary for the formation of red sediments had not reached 

 Illinois within the time of deposition of any portion of the McLeansboro now 

 preserved. 



In Bulletin 15 of the Illinois Coal Mining Investigations cited above, 

 Cady gives an account of the McLeansboro formation, from which the 

 following is abstracted : 



"The formation consists of several distinctive beds of shale and a minor 

 amount of sandstone, limestone, and coal. Although several of the coals above 

 No. 6 are persistent, none have been found sufficiently thick to be of commercial 

 value. They are significant only as correlation horizons. In its barrenness of 

 productive coals and in general age, the McLeansboro is similar to the Conemaugh 

 formation of Pennsylvania." 



' White, David, in the Danville Folio, No. 67, U. S. Geological Survey, 1900. 

 2 Cady, G. H., Illinois Coal Mine Investigations, Bull. 15, Coal Resources of District VI, 

 p. 26, 1916. 



