78 J. A. UDDEN 



The indicated correlation appears all the more probable, as 

 there exists under the phosphate-bearing rock in Tennessee an 

 unconformity, which is believed to be due "not to the existence 

 of a land area and subaerial erosion, but rather to non-deposi- 

 tion, by reason of strong marine currents." 1 The renewal of 

 the conditions of sedimentation in the paleozoic sea in the late 

 Devonian age may not have been quite simultaneous in the two 

 localities, though nothing is known to indicate the contrary, but 

 there seems to have been at any rate a parallel in the sequence 



of events. 



J. A. Udden. 



1 Loc. cit., p. 534. 



