tennessee and adjoining districts. 77 



Discussion. 



Mr. ToPLEY thought tho parallel drawn by the Author with the 

 Wealden area was in part justified, but there were differences 

 connected with minor points. The structure had been worked out 

 in detail for the ^Vealden area, but a similar state of things existed 

 in other parts of England. The watershed between the East Ten- 

 nessee valley and the Gulf of Mexico must have been greatly 

 lowered. 



Prof. Hughes asked if the gravels of the high terraces were com- 

 posed of Silurian or Carboniferous detritus, as he wished to know 

 whether the Carboniferous beds of the plateau had been continued 

 over the East Tennessee valley at the time of the formation of the 

 gorge. The northerly direction of the river after leaving the 

 plateau suggested change of level. 



Mr. Wills compared the area described with the gorge of the 

 A. von at Bristol. 



Dr. Hyland had not been led to any definite conclusion during 

 liis short stay in the region. 



The President found difficulties here, as elsewhere, in realizing 

 the form of the ground when the rivers began to flow, and in dis- 

 covering whether there were subterranean movements which aff'ected 

 the denudation. He felt that the explanation of the topography 

 might not be so simple as Prof. Hull made out, and would like to 

 have more details as to the structure of the ground. 



The Author, in reply, concurred with the remarks of the Pre- 

 sident as to the complex character of the subject. He thought the 

 fault drawn by Prof. Safibrd on the east side of the plateau had 

 little to do with the formation of the escarpment. He had no 

 evidence to adduce in answer to Prof. Hughes's question. There 

 was no more reason why the river should have flowed south on the 

 west than on the east of the plateau. 



Q. J. G. S.. No. 18G 



