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REVIEWS 105 



it is inferred that the date of submergence to this level preceded and 

 continued to the latest episode of glaciation, and that later influences 

 have removed the minor evidences of ice action. Upon this glaciated 

 bench there are now deposits of glacial gravel having the character- 

 istic forms of spits and bars, which are accordingly attributed to wave 

 and shore currents. These deposits indicate the presence of the sea 

 at this level after the retreat of the ice. 



The simplest explanation of the facts is that Ames Knob was sub- 

 merged beneath the sea to a depth of 80 feet above the present sea 

 level before, during, and immediately after the latest glacial episode. 



Permian Elements in the Dunkard Flora. By David White. 



The Dunkard series (Upper Barren Measures, XVI) comprises the 

 topmost Paleozoic sediments in the Appalachian trough. It occupies 

 a considerable area in southwestern Pennsylvania, northern West Vir- 

 ginia, and eastern Ohio, and the total thickness in northern West 

 Virginia is probably over 1,200 feet. In the absence of marine organ- 

 isms, the determination of the age of the beds rests on the fossil 

 flaras, the only important palaeontological evidence at present avail- 

 able. 



Extensive plant collections made at several localities were fully 

 described in 1880 by Professors William M. Fontaine and I. C. White, 

 who from their study of the flora and the lithology concluded that the 

 entire series was Permian. This conclusion has been questioned by 

 some American geologists and palseobotanists on account of the large 

 proportion of Coal-measures types, the paucity of genera and species 

 characteristic of the Permian of Europe, and the similarity as well as 

 continuity in the sedimentation. 



Additional material recently collected materially increases the 

 number of identical characteristic Permian species, which now includes 

 three species of Callipteris, in or above the Washington limestone, 

 while the examination of the types in other genera emphasize the Per- 

 mian aspect of a number of other forms. The data now available 

 leave little room for doubt that the upper part, of the Dunkard at 

 least is Permian, the stratigraphical occurrence of the species render- 

 ing it probable that the beds down to and including the Washington 

 Limestone, about 175 feet above the base of the series, may with 

 safety be referred to that period. The evidence as to the age of the 

 lower beds of the series is, in the judgment of the writer, not yet suffi- 



