Maryland Geological Survey 61 



The Magothy Formation 



Name and Synonymy. — The Magothy formation, so named by 

 Darton ' from the Magothy River, Maryland, where the formation is 

 typically developed, is now employed for the extension of these beds north- 

 ward into Delaware and New Jersey. Uhler employed the name " Alter- 

 nate Clay Sands " for portions of this formation, although he also 

 included other deposits under this designation. The Magothy deposits 

 have been for the most part included with the underlying strata, but there 

 can be no question of their distinctness from the Earitan formation. 



Areal Distribution. — The Magothy formation extends across the 

 state from the Delaware line to central Prince George's County. The 

 area of outcrop is much narrowed in Prince George's County until it 

 ultimately comes to occupy a very narrow belt to the east of the Earitan 

 formation. In Cecil, Kent, and Anne Arundel counties its outcrop varies 

 from two to three miles in width which is somewhat exceeded if the out- 

 liers on Elk Neck, Cecil County, and in northern Anne Arundel are 

 included. The continuity of the outcrops is very materially interfered 

 with by the Chesapeake Bay and several of the larger tidal streams, among 

 them Elk, Bohemia, Sassafras, Magothy, and Severn rivers. 



Lithologic Characters. — The Magothy formation is largely made up 

 of light-colored sands, at times coarse and conglomeratic. Some of the 

 beds are in places consolidated to form a brown sandstone, and the sands 

 themselves are at times highly colored by the admixture of hydroxide of 

 iron. Clays, generally drab or chocolate brown in color, also occur, 

 although the clay beds are subordinate to the sand beds in this formation. 

 The dark colored beds are often highly lignitic and at times pyritic. The 

 lignitic material is generally very finely divided, but it may occur in 

 larger masses. 



The deposits change rapidly in character both horizontally and ver- 

 tically and in this respect are not unlike the Earitan deposits. Cross- 

 bedding likewise occurs, but is on the whole less prominent than in the 

 earlier formation. At some of the localities the beds present a very 



1 Darton, N. H., Amer. Jour. Sci. 2d ser., vol. xlv, pp. 407-419, 1893. 

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