MARYLAND GEOLOGICAL SURVEY 101 



the geology of the surrounding regions. This scarp-line is one of the 

 most important topographic features within the city of Washington, 

 notwithstanding the fact that it has hern to a large extent built over and 

 has been somewhat modified by grading. In earlier days before the city 

 had grown to its present dimensions, this scarp-line was such a prominent 

 feat ure in the topography that almost every artist represented it in sketch- 

 ing panoramas of the city. Two of these early prints have been repro- 

 duced on Plate XIII. Even a cursory examination of them will suffice 

 to show the Wicomico-Talbot scarp-line. 



Interpretation of the Stratigraphic Record. 



The interpretation of the stratigraphic record has made it necessary 

 to correlate the various deposits not only within the Coastal Plain of 

 Maryland, but also beyond the borders of this State in adjoining terri- 

 tory. In making this correlation, the author has confined his conclu- 

 sions to those regions which have fallen under his direct observation. 

 They consist of the Potomac valley of Virginia and the Coastal Plain of 

 Maryland, Delaware, Pennsylvania, and New Jersey. Broader correla- 

 tions of the Maryland surficial deposits with regions more remote rest 

 on paleontological evidence and have been considered by Professor W. B. 

 Clark and Doctors F. A. Lucas and Arthur Hollick, who have contributed 

 chapters on the organic remains. 



Six classes of criteria have been employed by the author in correlating 

 the various deposits within the region mentioned above. These classes 

 are : fossil remains, similarity of materials, stage of decomposition, con- 

 tinuity of deposits, similarity of topographic form, and sequence in topo- 

 graphic position. 



POSSIL REMAINS. 



When the surficial deposits of Maryland are considered as a whole, it is 

 evident that fossil remains are not abundant or equably distributed. Up 

 to the present time none whatever have been discovered in the Lafayette. 

 The Sunderland, Wicomico, and Talbot formations have yielded plant 



