110 PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



VI. Section left hanh of Rappahannock River three-quarters of a mile 

 east of the mouth of Jetts Creek. 



Feet 

 Pleistocene Sand and gravel 10 



Eocene. Nanjemoy Argillaceous greensand more or less weathered. 



Contains a few casts, among which are speci- 

 mens of Corhuhi ahlrichi 20 



Total 30 



SECTIONS IN THE MATTAPONI RIVER VALLEY. 



Along the Mattaponi Eiver the Nanjemoy is exposed at the base of 

 the bluffs for a considerable distance with the upper portion of the bluffs 

 composed of diatomaceous earth or blue argillaceous sand belonging to 

 the Calvert formation. This line of contact, although undulating, is far 

 more regular than one would expect to find, for an extensive erosion interval 

 separates the two formations. The contact is usually about 15 to 20 feet 

 above the level of the water in the river. 



I. Section left bank of Mattaponi River about one-half mile below crossinij 



of the County road leading from Penola to Shumansville. 



Feet 

 Pleistocene Sand and gravel, not well exposed 8-10 



Eocene. Nanjemoy ' Dark, compact greensand containing casts of 



Venericardia potapoooensis IV2 



Aquia Glaunonitic sand separated from the overlying 



bed by a ferruginous sand layer 6V2 



Total 18 



II. Section left bank of Mattaponi River three or four miles below the 



preceding locality. 



A terrace, about 45 feet above the river level comes close to the river at 

 this point. There is no good section in the river bluff but by following a 

 short distance up a ravine the following imperfect section was observed. 



Feet 

 Pleistocene ( ?) Concealed about 20 



Miocene. Calvert Olive green or greenish-gray sandy clay.. about 18 



Eocene. Nanjemoy Compact greensand about 7 



Total 45 



