35 



Pamunkey river, commencing below the point at which the deposite 

 appears above the water's edge, and extending up the river to the 

 junction of the North end South Anna, where it terminates, has 

 served to develope the arrangement and composition of the strata, 

 and to determine the width of this portion of the formation. An 

 inspection of the most important Eocene localities on the James 

 river has also contributed many interesting and valuable facts, 

 while on the Rappahannock and Potomac, its western limits have 

 been determined with as much accuracy as could be attained by 

 transient observations directed only to a few localities. 



Wherever observed, the arrangement of the beds of the Eocene 

 and the minerals and fossils contained in them, have been found 

 strikingly alike, and hence the description of any transverse line of 

 the formation may be regarded as conveying a just representation 

 of its character throughout. At the same time, however, it is by 

 no means to he assumed, that in all localities the same arrange- 

 ment or composition of the strata must necessarily exist ; for within 

 a short distance in observations already made, considerable diversi- 

 ties have been observed to exist. But there can be little doubt 

 that the general order of the strata already remarked, as well as the 

 character of the fossils which they contain, will present much uni- 

 formity whenever the formation may be discovered within the 

 limits of the state. 



The existence of Miocene strata over the Eocene, has been re- 

 ferred to under a former head, and some account of this more 

 recent overlying deposite within the district of which we are now 

 treating, may, with propriety, be prefixed to the description of the 

 Eocene itself. 



Or THE MIOCENE WHICH OVERLIES THE EOCENE. 



Westward of the limits of the Miocene previously defined, the 

 general level of the country continues gradually to rise. A surface 

 more generally undulating, and strewed with water-worn fragments 

 of stone, sometimes of considerable size, marks our approach to 

 the region of hills and rocks, whence these memorials of the de- 

 structive forces of a former period have been derived. The 

 superficial strata in the western portion of this district js generally 4v>^ 

 a coarse sand or gravel, often containing large masses of rounded 

 sandstone and other rocks, of which the parent strata are gene- 



