Feb., 1916] Carbonaceous Material in the Monroe 



Vol 



and are to be found in only a few strata other than have been 

 mentioned. The buff stone is most carbonaceous where 

 it is nearest the gray. The odor test indicates that the buff 

 stone is equal to the gray in its carbon element. It also 

 manifests itself in three additional ways. 



First. — In breaking the buff stone we frequently find that 

 its looser texture has permitted the carbonaceous material to 

 gather between the rock particles. The stone appears as 

 though stained with some heavy black oil or fluid. 



Fig. 1. The Greenfield member of the Monroe formation, Rucker quarries, 

 Greenfield, Ohio. 



1. Drift. 



2. Buff stone, with heavy layers and carbon sheet zone toward the base. 



3. Graj^ stone, with carbon lines. 



Second. — Carbon sheets are more frequent and better 

 defined in the buff than in the gray stone. They occur between 

 the lower ledges; in fact, from two feet below to six or eight 

 feet above the contact of the gray and buff stones is the carbon 

 sheet zone. There seems to be a gradation from the profuse 

 carbon lines of the gray stone to their total absence in nearly 

 all of the buff. The dominant distinguishing feature of the 



