SECTIONS IN THE CHICKAHOMINY AND YORK RIVER VALLEYS. 



145 



is about 18 feet high of which the upper 3 to 6 feet consists of Talbot sand. 

 The shell layer varies in thickness but is rarely thicker than 2 feet. The 

 sand also carries some shells irregularly distributed through the mass. 



Y. Section at Burham's Wharf on the Rappahannock River. 



Feet 



Pleistocene Brown loamy sand 5% 



Stratified brown and yellow sand with a few 

 pebbles and cobbles (4 inches in diameter) 



at base 16 



Miocene. St. Mary's Greenish-gray slightly argillaceous fine sand, 



blue in color near base, where unweathered, 

 much stained with iron and containing nu- 

 merous casts and moulds of fossils and a few 

 shells of Melina maocillata 16 



Total 36% 



SECTIONS EXPOSED IN THE CHICKAHOMINY AND YORK RIVER VALLEYS. 



The St. Mary's formation is not well exposed in many places between 

 the Eappahannock and James rivers yet frequently enough to determine its 

 continuity. 



I. Section on left hank of Chickahominy River at Lanexa. 



Feet 

 Pleistocene Reddish-yellow clay (in some places decid- 

 edly red and in other places mottled) .... 10% 

 Thinly laminated drab and pink clay sep- 

 arated by thin films of fine sand 11 



Laminated, mottled (pink, drab, and yellow) 



clay 27 



Greenish-gray clay containing carbonaceous 

 matter 2 



Miocene. St. Marys Loose greenish-gray sand 3 



Shell bed. shells in matrix of sand similar to 

 above layer. The shells consist almost en- 

 tirely of Pecten eboreus and Pecten jef- 

 fersonius. Besides these there are a great 

 many specimens of Ecphora quadricostata, 

 Pecten clinionius, OrassatelUtes, Glycymer- 

 is, Venericardia granulata, Astarte, Den- 

 talium, Discinisca and Dosinia. All except 

 the pectens and ecphoras are exceedingly 



rotten 3-7 



Light-colored buff to gray sand, few fossils 7 

 Blue sand very compact, few fossils (ex- 

 posed to railroad track) 16 



Total 83y2 



Near the base of the above section the blue sand contains numerous 

 rounded nodules, many of which look like dumb-bells. Some of these 

 enclose a Pecten shell, and are II/2 feet long. 



10 



