120 PP. REPORT OF PROGRESS. FONTAINE & WHITE. 



1. The Evidence from the Identity of Species. 



2. The Evidence from Allied Species. 



3. The Evidence from the decadence of Coal Measure 

 forms. 



4. The introduction of Types characteristic of later For- 

 mations. 



5. The existence of an important Physical change at the 

 beginning of the Series. 



6. The nature of the Lithology ; the disappearance of 

 Coal ; the diminution in the Amount of Plant Life. 



The evidence of the animal life of the Upper Barrens is 

 of no particular weight in determining the question. So 

 far as it goes, it is favorable to the conclusion that the age 

 is Permian. 



It might perhaps be best to separate the roof shales of 

 the Waynesburg Coal and Wayuesburg Sandstone from 

 the beds overlying the sandstone, and as they contain a 

 mixed flora, consider them as transition beds of Permo- 

 Carboniferous age. Perhaps the strata down to and in- 

 cluding the great limestone overlying the Sewickley Coal 

 should be included with these, but in the absence of fossils 

 this cannot be decided. The beds above the Waynesburg 

 Sandstone should, however, be considered as strictly Per- 

 mian. 



If this conclusion be correct, it will have an important 

 bearing on the history of the changes which have affected 

 the Physical Geography of our portion of the North Amer- 

 ican Continent. Our great Appalachian Revolution would 

 have occurred at the close of the Permian Period, and in- 

 stead of standing almost alone, would be in harmony with 

 those mighty changes which elsewhere operated at the 

 close of the Permian to extinguish the forms of Palseozoic 

 life. 



It would also explain the absence of Permian beds in the 

 Mesozoic areas of the eastern portion of the Continent, and 

 the Triassic age of the oldest beds there found. For, if our 

 views be correct, the basins in which these beds were laid 

 down were formed at the close of the Permian, instead of 

 the Carboniferous proper. 



