MARYLAND GEOLOGICAL SURVEY 107 



decayed boulders in the Recent formation is sufficient to destroy any con- 

 fidence in the "stage of decomposition" as a method of discrimination 

 between the age of the various formations. Yet when the various forma- 

 tions are considered as a whole over the entire Coastal Plain of Maryland, 

 there is a perceptible difference between the stage of decomposition of 

 the Talbot when compared to that of all the other formations. As a whole, 

 its constituent parts show less decay. 



It is obvious from this discussion that the author found little aid in 

 attempting to correlate the deposits by using " fossil remains," " simi- 

 larity of material," or " state of decomposition." The most that can be 

 said of them is that in certain cases they were found useful in corrobo- 

 rating evidence derived from employing the remaining three classes of 

 criteria mentioned above. When taken by themselves, they were unsatis- 

 factory. 



The classes of criteria which the author found most serviceable in dis- 

 criminating between the various surficial formations were " continuity 

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

 graphic position." These three criteria are all essentially topographic in 

 their characteristics and application. Their value as methods of corre- 

 lation and discrimination rests on evidence now being furnished by the 

 activities of the estuarine systems of the Chesapeake and Delaware bays 

 and the Atlantic ocean. In. other words, the key to the correct interpre- 

 tation of the surficial deposits of the Middle Atlantic slope is to be found, 

 first, in the topographic form of the Recent terrace; second, in its con- 

 tinuous development beneath a wave-cut cliff along the shores of the 

 Chesapeake-Delaware Bay systems, as well as under the Atlantic ocean 

 to the edge of the continental shelf; and third, in the way this terrace 

 would appear if it were elevated and eroded for any given period of time. 

 Before discussing the last three criteria of discrimination, this Recent 

 terrace will be briefly considered. 



At the present time the waves of the Atlantic ocean and Chesapeake 

 Bay are engaged in tearing away the land along their margins and in de- 

 positing it on a subaqueous platform or terrace. This terrace is every- 

 where present in a more or less perfect state of development, and may be 



