74 PHYSIOGRAPHY AXD GEOLOGY OF THE COASTAL PLAIN PROVINCE, 



occasional exposures of the usual gray coarse arkosic and more or less 

 lithified sandstone of the Patuxent, which rises from 10 to 15 feet above 

 tide and is overlain for the most part by Aquia Eocene. At the mouth of 

 the Massaponax the following section occurs. 



I. Section left hank of Rappahannock River, opposite mouth of Massaponax 



Creek. 



, . Feet 



Pleistooene Sand and gravel about 12 



Eocene. Aquia Weathered argillaceous greensand 5 



Lower Cretaceous. Patuxent Coarse arkosic sand with gravel and angular 



clay pellets 20 



Total 37 



The last exposure seen on tlie Eappahannock is along the right bank 

 half a mile below Massaponax Creek, where tlie following section occurs: 



II. Section half mile below last, right hank. 



Feet 



Pleistocene Mostly concealed 20 



Eocene. Aquia Poorly exposed glauconitio sand 22 



Lower Cretaceous. Patuxent Coarse gravelly compaet arkosic sand 12 



Total 54 



JAMES RIVER SECTIONS. 



At Eichmond the crystallines are exposed in the bed of the river, and 

 their contact with the Patuxent is not seen, because of the low banks whicli 

 are continuous for several miles below that town. Several low bluffs along 

 the left bank between Eichmond and Drewry's Bluff show a few feet of 

 Patuxent arkosic argillaceous sands beneath 10 to 30 feet of Pleisto- 

 cene. The section of Drewry's Bluff shows the best exposure of the Patuxent 

 formation on the river and is continuous along the right bank for over half 

 a mile. The lateral variation of the materials is considerable and affords 

 an excellent idea of the marked changes in lithology which are typical of 

 the Patuxent, particularly in this area. 



