570 REVIEWS 
graphically it is composed of a set of five terraces designated, from the 
names of the formations covering them, as Lafayette, Sunderland, 
Wicomico, Talbot, and Recent. 
The upper one, the Lafayette, has a maximum height above sea- 
level of about 500 feet. It is well preserved in Fairfax County, where 
it slopes gently to an elevation of about 200 feet and ends at the margin 
of the Sunderland terrace. The Sunderland terrace penetrates re- 
entrants into the Lafayette, and the two are, in places, separated by a 
well-marked scarp line. It is well developed in the central part of the 
province. Its eastern limit is the roo-foot contour. The Wicomico 
terrace borders the Sunderland and wraps around it about 20 feet 
below. From the contact it slopes gradually to the east and terminates 
at the escarpment representing the west edge of the Talbot terrace. 
The latter surrounds the Wicomico as a border and is separated from 
it by a sharp line of cliffs 10 to 20 feet high. The scarp is conspi uous 
just west of the Dismal Swamp. The eastern limit of the Talbot terrace 
is either a wave-cut cliff or the modern beach. The Recent terrace is 
almost wholly submerged. 
The oldest series of sediments exposed on the Coastal Plain is the 
Lower Cretaceous. The lowest member of this series, the Potomac 
group, was laid down as a mixture of terrestrial, lacustrine, and fluviatile 
sediments, as indicated by the absence of any strictly marine fossils, 
and by the presence of estuarine species of shells. The flora is varied 
and includes equiseta, ferns, cycads, conifers, monocotyledons, and 
dicotyledons. The exposed thickness of the series in Virginia is about 
500 feet, but a recent well at Fortress Monroe has penetrated 1,300 feet, 
showing an increasing thickness to the east. 
The Patuxent beds rest for the most part upon the crystalline rocks 
of the Piedmont area, but near Doswell they lie upon the Triassic. The 
outcrops are conspicuous at the head of tide in the main drainage basins. 
The Arundel formation is not recognized in Virginia. The relation of 
the Patapsco beds to the Patuxent is one of decided unconformity, and 
the irregular erosion surface of the Patapsco is emphasized by the marine 
character of the overlying deposits. These resemble the Patuxent in 
their varied materials but are, in general, finer. The outcrops are best 
seen along the Potomac River near Washington. 
Upper Cretaceous beds are not exposed in the region, but borings 
for wells have brought up fossils which have been identified as Upper 
Cretaceous. The material resembles the Matawan formation of Mary- 
land and New Jersey. 
