Maryland Geological Survey 63 



Farther south in Anne Arundel County it has been estimated to have 

 a maximum thickness of about 60 feet on the Magothy Eiver, which 

 declines to about 30 feet on the Severn River, and in central Prince 

 George's County it rarely reaches more than 10 to 15 feet. 



Stratigraphic and Structural Relations. — The Magothy forma- 

 tion overlies the Raritan unconformably and gradually transgresses that 

 formation southward, although it does not entirely overlap it along the 

 line of outcrop. The contact at times is not very sharply defined on 

 account of the unconsolidated character of the materials, but a broad 

 study of the relations indicates the unconformable nature of the contact. 



The Matawan formation also overlies the Magothy formation uncon- 

 formably and likewise transgresses it southward, although over much of 

 Prince George's County the transgression by still later formations makes 

 it impossible to determine the extent of this overlap to the southward. 

 The stratigraphy and structure of the Magothy beds is complex and, as 

 in the case of the Raritan formation, the wide variability in the character 

 of the materials renders it impossible to subdivide the Magothy into 

 members of more than local importance. 



The relatively limited area of outcrop of the Magothy formation has 

 afforded little if any evidence of warping, although the slightly greater 

 dip in the more western outliers as compared with the main body of 

 the formation suggests that there may have been some deformation along 

 the " fall-line." 



Organic Remains. — The Magothy formation has afforded both animal 

 and plant fossils. The animal remains, chiefly marine mollusks, are con- 

 fined to a few localities in the extreme northern and southern portions of 

 its outcrop. The locality at Cliffwood, New Jersey, has long been known 

 and has afforded a considerable marine fauna, while a similar occurrence 

 on Good Hope Hill, District of Columbia, near the southern extremity of 

 the occurrence of the Magothy has likewise afforded a number of similar 

 forms. 



The Magothy fauna in Maryland is unfortunately known from but 

 a single locality, Good Hope Hill, near Anacostia, D. C. By far the 

 most abundant species, a small Corbula, suggesting the C. bisulcata of 



