THE COAL MEASURES OF ARKANSAS 365 



of the Carboniferous deposits of the Continental Interior. It is 

 also representative of the conditions existing at the present day 

 on the Gulf coast, and is typical of sedimentation generally. 



A diagrammatic cross-section, north and south, from Minne- 

 sota to central Arkansas, and representing the relations of the 

 Carboniferous deposits of the region, is given in Fig. 2. 



The true marine beds of the Missourian series, or "Upper 

 Coal Measures," may have extended, and probably did stretch 

 out over a considerable part, and possibly all, of the region ; 

 but erosion, since Carboniferous times, has removed all traces 

 of these deposits. 



Charles R. Keyes. 



