G. I). Harris — Tertiary Geology of Maryland. 21 



Art. II. — The Tertiary Geology of Calvert Cliffs, Mary- 

 land ;* by Gilbert D. Harris, Washington, D. C. 



(Communicated by permission of the Director of the U. S. Geologicai Survey.) 



On the Bay shore of Calvert county, Maryland, extends a 

 long series of high cliffs, remarkable for their abruptness and 

 continuity. Here and there, to be sure, occur narrow channels of 

 bayward flowing streams, but extensive stretches of lowlands 

 are wanting. It therefore becomes possible to trace every im- 

 portant stratum represented in these cliffs from its northern- 

 most outcrop to where its southern dip carries it beneath tide 

 level. This task has actually been attempted ; and the series 

 of sections given in the map, p. 23, shows diagramatically some 

 of the results obtained. 



Herring bay, Section 1. — This locality is somewhat north of 

 Calvert cliffs proper, and the horizon of its fossiliferous expo- 

 sure has not been definitely correlated with those farther south ; 

 yet on paleontologic grounds alone, it is safe to say that the 

 lower portion of Section 1 is stratigraphically equivalent to, or 

 somewhat below Zone a of Sections 2 and 3. 



Conradf mentions from this locality : 



Bones of Cetacea, siliceous casts of marine shells, Ostrea per- 

 crassa, Pecten Humphreysii. 



The present writer's list includes : 



Ostrea percrassa, Pecten Humphreysii, Pecten madisonius, Stri- 

 arca centenaria, Thracia Conradi ?, Carditamera arata, Lucina 

 subplanata, Crassatella melina, Corbula elevata, Astarte varians, 

 siliceous casts of a Turritella, probably T. Mortoni from neigh- 

 boring Eocene deposits, Discina lugubris. 



These fossils consist of casts only, and are found in the 

 lower 10 feet of Section 1. The matrix is a bluish green 

 sandy clay. Above lie variable thicknesses of diatomaceous 

 earth, sand, and clay, all of a light yellowish hue, rarely con- 

 taining molluscan remains, though small Nuculidm were in 

 one instance seen at an elevation of 30 feet above the level of 

 the Bay. 



Section 2. — About one mile south of Fishing creek the fol- 

 lowing section occurs : 



*The field observations upon which this essay is based were made under the 

 auspices of the U. S. Geological Survey, April 23-30. 1891. and May 23-June 1, 

 1892. During the latter period, the writer was accompanied by Mr. Frank Burns, 

 whose diligence and skill at collecting very materially aided in procuring the 

 results here presented. 



f Proceed. Nat. Inst., 2d Bull., 1842, p. 181. 



