SECTIONS ALONG POTOMAC RIVER. 105 



Areal distribution.— The Nanjemoy formation outcrops along a narrow 

 belt to the east of the Aquia formation. It is well exposed where the Aquia 

 disappears beneath tide. The Nanjemoy is also exposed in the lower courses 

 of most of the tributary streams flowing into the Potomac and Eappahan- 

 nock rivers in the eastern part of King George and Caroline counties, along 

 the Pamunkey Eiver between King William and Hanover counties, and 

 along the James Eiver in the vicinity of City Point. The upper surface 

 of the Nanjemoy disappears below tide just below Mathias Point on the 

 Potomac, a short distance below Port Eoyal on the Eappahannock, and at 

 the mouth of Powells Creek, about seven miles below City Point on the 

 James Eiver. The Nanjemoy has not been recognized on the Nottoway 

 Eiver. 



DETAILED SECTIONS. 



SECTIONS ALONG POTOMAC RIVER. 



The sections of the Nanjemoy formation exposed along the Potomac 

 Eiver and its tributaries are among the best to be found in the State. They 

 occur in King George County where the current of the river is deflected 

 against the Virginia shore on account of the river turning sharply to the 

 left at this point. Prominent blufi^s result from the erosive action of the 

 water and in these bluffs are many good exposures of Nanjemoy strata. 

 At Mathias Point the river turns somewhat less abruptly to the right and 

 high bluffs have been formed on the Maryland shore near Pope's Creek. 

 A few sections from near that place are included to show the characteristics 

 of the entire formation along the valley of the Potomac Eiver. 



I. Section on the south side of Potomac Creeh, about one and one-half 

 miles east of the railroad. 



Feet 

 Eocene. Nanjemoy Potapaco Gray sand with some glauconite, and a few 



casts 12 



Very compact white clay blotched with limo- 



nite stains 7 



Compact pink clay, no fossils 17 



Aquia Paspotansa Glauconitic sand with occasional layers of fos- 

 sil casts 30 



Total 66 



