THE TERTIARY FORMATIONS OF VIRGINIA. 351 



Here no trace of fossils of either the eocene or meiocene period 

 could be discovered, the bank consisting exclusively of diluvial sand 

 and gravel. But still further down the river, beds of the latter are 

 observed, and these continue, at intervals, to near the extremity of the 

 peninsula. 



An equally marked termination of the eocene is presented in the 

 neighbourhood of Mathias's Point, on the Potomac. At Woodstock, 

 about one-third of a mile above the Point, the cliffs rise to the height 

 of from forty to fifty feet, exhibiting an exposure of the eocene strata, 

 reaching to a distance of nearly twenty-five feet above the surface of 

 the river. The lower bed, about eight or nine feet thick, is rich in 

 the fossils characteristic of the eocene, but the layer, incumbent on 

 this, though filled with ferruginous impressions of shells, retains none 

 of the shells in an unchanged condition. The bed of reddish clay 

 which forms the upper portion of the bank, is separated from the strata 

 just described by a thin band of ferruginous gravel and sandstone, such 

 as is frequently seen occupying a similar position on the Pamunky and 

 in other localities. 



Above this place, on the adjacent estate called " Borodino," the resi- 

 dence of Mr Parke, the banks, after sinking to a level with the flats, 

 again rise, with some abruptness, to an elevation of from forty to sixty 

 feet. The lower stratum of the marl, containing shells in considera- 

 ble number, is here but little raised above the level of the water. A 

 layer deeply tinged with green sand, and blotched with oxide of iron, 

 rests on this to the height of from four to five feet. Another, but not 

 fossiliferous bed, belonging to the same series, reposes upon the latter, 

 but the piles of fallen earth at present preclude an accurate examina- 

 tion of its character and extent. Still further westward, at "Albion," 

 the estate of Mr Mason, the fossiliferous eocene strata vary from four to 

 seven feet in height above the river, and are overlaid by heavy beds of 

 whitish and mottled clay. Strata recur, at intervals, in ascending the 

 river, rising to greater elevations, and presenting a greater abundance 

 and variety of fossils as we proceed. 



Below Woodstock the banks gradually decline, and on the side of a 

 little creek or gut between this and Mathias's Point, the eocene strata 

 entirely disappear. To the east of this creek and at the Point, the 



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