1889] MARYLAND ACADEMY OF SCIENCES. 53 



area in New Jersey, is now but meagerly represented in the 

 Cretaceous formation of the Western Shore. Whether it once 

 occupied a wide tract of country across the middle of Anne 

 Arundel and Prince George's counties it seems now impossible 

 to discover, but eroded remnants of it may be found in the 

 highlands between the head of the estuary of the INIagothy river 

 and Round Bay, and again in the high hills above Indian Land- 

 ing, northeast of Severn Run. Patches of this same marly clay 

 appear at intervals across Anne Arundel county, and pass 

 through Prince George's county on a sinuous line about two 

 miles southeast of the Baltimore and Potomac railroad. But, 

 as the western hills of debris are approached, before reaching 

 the head of Eastern Branch of the Potomac river, these last 

 remnants of the greensand marl are set farther away in the 

 country towards the south, and finally disappear as the white 

 and red clays become conspicuous. 



Eocene. — After all of the Cretaceous strata had been laid 

 down and consolidated, the ocean again covered the land, 

 apparently some distance further inland than its predecessor. 

 But before much of the Eocene was deposited, the surface of the 

 Cretaceous was deeply excavated, so that round-topped hills 

 were built near the inner border of that formation, and tortuous 

 channels led out towards the more open ocean. Greensand 

 grains must still have been precipitated to the bottom of the 

 w^ater, since the greater part of the Eocene formation which 

 immediately followed w^as to a great degree composed of glau- 

 conitic material. Doubtless some of the greensand was derived 

 from the excavation of the Cretaceous marl resting on the shores 

 and floor of the ocean ; but as most of this material remains 

 unaltered in the well preserved Eocene marls, it appears evident 

 that it was derived from a fresh source of supply. The wear 

 and tear of an eroding ocean now opened the way for the deposit 

 of the Eocene beds, and these were laid down continuously over 

 a large part of the Cretaceous, extending now over its hilly 

 bottom, and then throughout the intervening channels and hol- 

 lows. A series of thick beds of black micaceous marl, green- 

 sand marls, grayish marls, greenish sandy micaceous marls, 

 marly loam, ferruginous sandy loam, aluminous fine whitish 



