1()0 PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



cene materials on the Eastern Shores of both Maryland and Virginia. It is 

 well exposed at Yorktown on the York Eiver, at Smithfield on a tributary 

 of the James Eiver, and in the vicinity of Suffolk. The prevailing low topog- 

 raphy in the region of outcrop of the Yorktown formation results in fewer 

 exposures than in the case of the other Miocene formations. The formation 

 has been traced southward into North Carolina wliere it is exposed 

 in numerous places along the Chowan River and its tril)utaries. 



DETAILED SECTIONS. 



The Yorktown formation is well developed in the southeastern portion of 

 the State in a belt extending southward from Gloucester County to the North 

 Carolina line. In this region outcrops are numerous along many of the 

 streams although only along the large estuaries can thick sections be 

 observed. Fragmental shell beds which constitute the most distinctive lith- 

 ologic features of the formation and distinguish it from any of the other 

 Miocene formations of this region, outcrop in many places. 



SECTIONS IN THE YORK RIVER VALLEY. 



The Yorktown formation has its typical development in the region of 

 Yorktown where extremely fossiliferous strata in the high bluffs have long 

 been known to contain a great variety of well preserved fossils. No other 

 locality in the State has furnished so many species or has received so much 

 attention from paleontologists. The beds that outcrop in the vicinity of 

 Yorktown extend through the adjoining counties and are exposed along 

 many of the small streams. 



At Stubb's Pond I14 miles northwest of Sassafras there is an exposure 

 of about 8 feet of shell marl consisting principally of Pecten jelfersotiius with 

 numerous specimens of Area, Ostrea. Venus, Ecphora. etc. The marl is over- 

 lain by about 30 feet of Pleistocene strata, the lower portion of which is 

 rather sandy and contains some small pebbles but grades upward into a 

 mottled red and drab clay. 



On the valley slope of Poplar Spring Branch in Gloucester County there 

 are poor exposures of Pleistocene and Yorktown materials. The lower 35 to 

 40 feet consists of drab clay and bufE-colored Miocene (Yorktown) sand, the 

 upper 30 feet of Pleistocene material similar to that described in the preced- 

 ing note. 



One-quarter mile north of Money a shell layer about 8 feet thick outcrops 

 near stream. 



