13 



deeply tinged by mixture with greensand, lies immediately upon 

 this irregular surface, and the whole is covered with a bed of gravel 

 and sand, with diagonal lines of stratification, indicating the agency 

 of currents at the time of its deposition. 



At Mr. William Wickham's, the overlying stratum consists of 

 bands of ferruginous gravel and sand, containing round concretions, 

 like Geodes, generally filled with sand. Thin seams of iron ore run 

 along this stratum a few feet above the fossiliferous beds. These 

 latter, in some places, present a level outline, and are then always 

 covered by a layer of sandy clay containing much greensand. On 

 the other hand, where the outline is undulating and irregular, a stra- 

 tum of gravel rests immediately in contact with the bed of marl. 

 The size of the gravel thus deposited, as well as the scooped surface 

 of the bed on which it reposes, indicating the operation of powerful 

 currents after the deposition of the strata of Eocene, presents an ex- 

 planation of the absence in these places of the upper bed of this for- 

 mation, remarked as present in those spots, where there are no such 

 indications of the action of destructive forces. The matrix of the 

 fossils is sometimes an olive-coloured clay, sometimes a grayish-green 

 sand and clay, and sometimes a bluish-black clay, conta ling a large 

 proportion of the granules of greensand. The depth of the marl is 

 15 feet. 



EOCENE STRATA OP THE JAMES RIVER. 



The beds of Eocene on the James river first make their appear- 

 ance on its southern shore near Coggin's Point, and thence continue, 

 except when interrupted by the river flats, to a small distance above 

 City Point, making a distance following the flexures of the shores of 

 about ten miles. On the opposite side they have been found at 

 Berkeley and other'points, but as yet this portion of the deposite has 

 been but little examined. 



At Coggin's Point, Tarbay and Evergreen, the cliffs have a height 

 varying from 30 to 40 feet. The Miocene marl, which in some 

 places is seen overlying the Eocene, abounds in scallops and other 

 shells which make it easily recognised. Beneath this and usually 

 separated from it by a thin line of black pebbles, like those occurring 

 on the Pamunkcy, there occurs a stratum of a greenish-red and yel- 

 low aspect, containing much greensand and gypsum; the latter 

 partly disseminated in small grains, and partly grouped in large and 

 massive crystals. The under stratum, rich in greensand and con- 



