277] B. Wade 79 



fauna of Maryland. The shells, notably the bivalves, are 

 probably more abundant at Brightseat, but not so well pre- 

 served as they are at the Tennessee locality. The sediments 

 containing the Coon Creek fauna are dark bluish green and 

 gray clayey sands. The sand is of medium fineness and con- 

 sists of angular and rounded grains of quartz as the major con- 

 stituent, with glauconite, small flakes of mica, and shell frag- 

 ments as minor constituents. Pieces of lignitic wood and 

 small nodular masses of pyrite are common but not abundant. 

 All of the above elastics are cemented together with a fine 

 calcareous material, forming a compact impervious mass 

 which varies locally in arenaceous and argillaceous content. 

 There is locally sufficient lime for the matrix to become indu- 

 rated into a very hard, impure and concretionary limestone. 

 When this marl is thoroughly weathered the shells are re- 

 moved leaving casts in a matrix which becomes yellowish 

 brown in color, due to the oxidation of the glauconite and 

 other ferruginous constituents. Dr. Paul C. Bowers, Chief 

 Chemist for the Tennessee Geological Survey, has made a 

 careful quantitative analysis of this marl and reports the 

 following results : 



Si0 2 65.30 



Al o O 3 8.56 



Fe 2 3 3.72 



FeO 1.72 



MnO 44 



CaO 7.10 



: 70 



ff\ 2 - 42 



P trace 



2 5 



FeS 2 45 



C0 2 5.15 



H 2 5.45 



Carbon 09 



Total . ..101.00 



