Maryland Geological Survey 27 



erally been held to be of the simplest character, possess in reality much 

 complexity along their western margins, and it is not uncommon to find 

 that intermediate members of the series are lacking, as the result of 

 transgression, so that the discrimination of the different horizons, in the 

 absence of fossils, often requires the utmost care. 



The Coastal Plain sediments were laid down after a long break in 

 time following the deposition of the red sandstones and shales (Newark 

 formation) of late Triassic age, which overlie the crystalline rocks of 

 the western division of the Piedmont Plateau, and complete the sequence 

 of geological formations found represented in Maryland and Delaware. 

 From the time deposition opened 'in the coastal region duiing early 

 Cretaceous time to the present, constant sedimentation has apparently 

 been going on, notwithstanding the fact that frequent unconformities 

 appear along the landward margins of the different formations. 



The formations consist of the following: 



Formations of the Coastal Plain. 



Ceuozoic. 

 Quaternary. 

 Recent. 



Pleistocene Talbot ] 



■Wicomico L = Columbia Group. 



Sunderland j 



Tertiary. 



Pliocene (?) Lafayette. 



Miocene St. Mary's ^ 



Cboptank I =: Chesapeake Group. 



Calvert J 



Eocene Nanjemoy i „ , _, 



L = Pamunkey Group. 

 Aquia J 



Mesozoic. 



Cretaceous. 



Upper Cretaceous Rancocas. ' 



Monmouth. 



Matawan. 



Magothy. 



Raritan. 

 Lower Cretaceous Patapsco "1 



Arundel I = Potomac Group. 



Patuxent 



