MARYLAND GEOLOGICAL SURVEY 159 



At Grove Point the waves of Chesapeake Bay have cut a clean 

 and almost perpendicular sea-cliff, varying in height from 20 to 50 

 or 60 feet. Toward the northern end of this escarpment the 

 Raritan appears at the base, but throughout the middle and southern 

 portions of this sea-cliff the base of the precipice is composed of the 

 Matawan formation. At this place it is made up of a dense and 

 slightly micaceous, bluish green clay, which rises in a perpendicular 

 bank to a height varying from 5 to 20 feet above tide. It lies here, 

 as well as on Maulden Mountain, unconformably on the Raritan. 

 This relation of the two deposits is clearly shown at the northern 

 end of the cliff (Plate XIII, Fig. 1). Toward the southern end the 

 contact disappears below tide, and the Matawan gradually passes 

 down deeper and deeper beneath the beach. In this locality the 

 Matawan contains considerable lignite and pyrite and is strongly 

 impregnated with sulphur, as is indicated by the strong odor arising 

 from the exposed surfaces. Above the Matawan there is an uncon- 

 formable mass of loam, sand and gravel of varying thickness belong- 

 ing to the Columbia group. Other exposures of Matawan in Cecil 

 county are of minor importance and of inferior character. 



The structure of the Matawan formation is as simple as that of 

 the underlying Potomac beds. It crosses the county from northeast 

 to southwest, and dips beneath the overlying formations at the rate 

 of about 20 feet to the mile. 



Up to the present time the Matawan has yielded in this county 

 no other fossils than lignite. 



THE MONMOUTH FORMATION. 



The Monmouth formation, named from its typical locality in Mon- 

 mouth county, New Jersey, has been divided into two members, 

 the Eavesink marls at the base and the Red Bank sands above. 

 The Navesink is typically exposed in the Navesink Highlands, New 

 Jersey, and the Red Bank sands in the vicinity of Red Bank in the 

 same state. These two localities suggest the names which have 

 been applied to these members of the Monmouth formation. The 

 Monmouth is Upper Cretaceous in age, lies conformably on the 



