THE TALBOT FORMATION. 185 



Areal distribution. — The distribution of the Wicomico strata is the same 

 as that of the terrace of the same name described in the chapter on phys- 

 iography. It occupies the uplands between the lower courses of the large 

 estuaries and frequently extends up the larger valleys as a narrow or wide 

 discontinuous terrace to the head of tide-water. Along the peninsulas 

 between the James and Potomac rivers the AYicomico forms a band of vari- 

 able width occupying a position between the Sunderland covered divides 

 and the Talbot terrace that skirts the rivers and Chesapeake Bay. South 

 of the James River, however, the Wicomico occupies a wide area extending 

 from the James River to the Xorth Carolina line and beyond, and from 

 the western margin of the Dismal Swamp to the vicinity of the Blackwater 

 River. In this broad area the Sunderland is absent and the Wicomico for- 

 mation covers the stream divides which are broad and flat, while the streams 

 have cut shallow valleys below the general level of the surrounding country. 

 An escarpment separates the formation from the Sunderland formation 

 above and another divides it from the lower-lying Talbot formation. The 

 escarpment between the Wicomico and Talbot is very well marked in many 

 places, being especially well-developed along the western margin of the 

 Dismal Swamp and from there continues almost due north to the James 

 River. It is also plainly shown between the James and York rivers between 

 Newport News and Yorktown, and north of Gloucester Point on the penin- 

 sula between the York and Rappahannock rivers. The Wicomico surface 

 is very conspicuous along the upper estuarine portion of the Rappahannock 

 River where it is frequently over a mile in width and forms a pronounced 

 terrace below the Sunderland deposits that cover the divides. 



The Talbot Formation. 



Name. — The Talbot formation has received its name from Talbot 

 County, Maryland, where the deposits of this age form a broad terrace 

 bordering the numerous estuaries. 



Lithologic character. — The materials which compose the Talbot forma- 

 tion consist of clay loam, peat, sand, gravel, and ice-borne boulders. As in 

 the Sunderland and Wicomico formations, these materials grade into each 

 other both vertically and horizontally and the same bipartite division with 

 the coarser materials beneath and the finer ones above is present in the 

 Talbot a? in the others. There is on the whole much less deca3^ed material 

 in the Talbot than in the two preceding formations and this gives to the 

 formation a much younger appearance although this difference cannot be 



