SECTIONS IN THE MATTAPONI RIVER VALLEY. 



113 



About 4I/2 or 5 miles below Eeedy's Mill Bridge a few 

 N"aiijemoy fossils, principally Venericardia potapacoensis, were collected 

 in a section similar to the preceding. From the preceding locality to the 

 mouth of Marricossick Creek, a distance of about 5 miles, Nanjemoy 

 greensand and dark green clay continue to form the base of low sections. 

 At one point a few miles above the mouth of the creek on the right the 

 upland is washed by the river. The high river bluff resulting is not well 

 exposed but 30 or 40 feet above the base greenish Miocene clays were 

 observed, containing casts of Turritella plebeia. 



A'lTI. Section on Mattaponi River at the moutli of Marricossick CreeJc. 



Feet 

 Pleistocene Sand and gravel 4 



Eocenp. Nanjemoy Dark green argillaceous greensand 12 



Total 16 



About two miles below the mouth of Marricossick Creek the river 

 touches the base of a high upland rising 100 feet or more above the water 

 level. The bluff is overgrown with vegetation to such an extent that only 

 about 8 feet of Eocene greensand is exposed at the base. A number of 

 fossils are present in this basal bed, among them being Venericardia 

 potapacoensis, a number of small pelecypods, and some gastropods. 



From the mouth of Marricossick Creek to the first county bridge below, 

 a distance of about 5 miles, the Eocene greensand continues to appear 

 at the base of a Pleistocene terrace. Not far above the bridge the Nanjemoy 

 strata rise as much as 15 feet above the level of the water. On the left 

 near the end of the bridge the road ascends a scarp some 25 or 30 feet above 

 the river level. Toward the top light-colored clays of the Calvert formation 

 are poorly exposed in the road. 



IX. Section right hanlc of Mattaponi River, eleven miles hrlow mouth of 



MarricossicTc Creek. 



Feet 

 Pleistocene Sand and gravel 8 



Miocene. Calvert Dark greenish clay at top grading downward 



into greenish argillaceous sand which has 

 been derived from the Kocene and reworked. 

 Along the base a thin band of gravel consist- 

 ing of quartz and phosphate pebbles, etc., 

 occurs 23 



Eocene. Nanjemoy Greensand 4 



Total 35 



