18G PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



always relied on. The Talbot also contains less coarse material than do 

 the other two Pleistocene formations. Sand and loam predominate, 

 although some gravel and boulders occur either in bands or irregularly 

 distributed through the finer materials in almost every region where the 

 formation is developed. The Potomac Eiver evidently brought down a great 

 many glacial boulders during the Talbot submergence, and these carried 

 by floating ice were dropped in the various deposits then forming. A num- 

 ber of these have been found in the region of Washington which show their 

 glacial character by the planation they have suffered and the glacial striae 

 they bear. Some of them may have come from the earlier Pleistocene 

 deposits, and have been re-deposited, but it is improbable that many have had 

 such an origin. 



The materials of the Talbot were derived in part from the destruction 

 of the older Pleistocene strata and the underlying Cretaceous and Tertiary 

 formations by the waves of the Talbot sea and its estuaries, yet, as in the pre- 

 ceding periods, the streams doubtless brought down much additional 

 material from the Piedmont Plateau and the Appalachian region beyond. 

 The Talbot materials therefore like those of the preceding formations are 

 exceedingly Jieterogeneous in character. 



A type of deposit not thus far recognized in the older Pleistocene for- 

 mations in Virginia, althougli occurring in them elsewhere, is peat which 

 is developed extensively along the Rappahannock River. About a mile 

 above Tappahannock the river has cut into an old Talbot swamp deposit 

 containing peat and many upright cypress stumps which are still in an 

 excellent state of preservation. 



Section exposed in Rappalianvoch River bluff, one mile above Tap- 

 pahannock. 



Feet 



Yellowish-brown loam grading downward into sand 12 



\Yhite to asli-colored fine sand 4 



Band of fine gravel with a few pebbles an inch in diameter 31/2 



Drab clay containing pieces of lignite and plant impressions with many cypress 

 knees and stumps derived from the bed below ' 0-4 



Compact brown to black peat containing numerous upright cypress knees and 

 stumps in place, some of the stumps repelling 4 feet in height and 5 feet in 

 diameter (exposed) I-41/. 



Total 28 



The river in cutting into the deposit has removed in places the clay and 

 peat, leaving many knees and stumps exposed. The line of separation 



