Maryland Geological Survey 29 



The total average thickness of the Lower Cretaceous formations in 

 Maryland is between 600 and 700 feet, and they show an average dip 

 of about 40 feet in the mile to the southeast. 



Upper Cretaceous 



The deposits referred to the Upper Cretaceous comprise the Karitan, 

 Magothy, Matawan, Monmouth, and Eancocas formations. The two 

 lower formations are estuarine and fluviatile in origin, while the over- 

 lying formations are distinctly marine. All of these formations can be 

 traced to the northward into Delaware and New Jersey, where they 

 attain an even larger development than in Maryland. To the southward 

 they are gradually overlapped, one after the other, by the Tertiary 

 formations and are unknown in Virginia. Similar deposits are found 

 in North Carolina and the States which lie to the south of it but are 

 known under other formational names. 



The four upper formations form an apparently conformable series 

 resting unconformably upon the Earitan formation, which in turn over- 

 lies the Patapsco formation unconformably. A slight unconformity may 

 perhaps exist between the Magothy and the Matawan, although a fuller 

 study of the relation of these formations indicates that they are prob- 

 ably conformable over the greater portion of the area of outcrop. The 

 deposits consist chiefly of sands and clays, with some gravels in the two 

 lower formations, while the three higher formations consist more par- 

 ticularly of clays and sands, the latter often somewhat glauconitic, 

 although much less so than similar deposits in New Jersey. The Eari- 

 tan formation consists chiefly of thick-bedded and light-colored sands 

 with some gravels. Clays generally light in color occur in the lower 

 portion of the formation. The Magothy formation is made up of sands 

 and clays that change rapidly both horizontally and vertically, finely 

 laminated clays with sand layers and more or less carbonaceous often 

 appearing. The Matawan formation is composed of micaceous, sandy 

 clays somewhat more sandy at times in the upper portion and more 

 argillaceous in the lower portion of the formation. The Monmouth 

 formation consists of reddish and pinkish sands more or, less glauconitic 



