14 BULLETIN 159, TJ. S. DEPARTMENT OF AGRICULTURE. 



materials form a basal bed underlying loam or silt loam coverings, 

 although extensive areas of sandy surface material are found along 

 the estuarine rivers of the section and within the seaward margin 

 of the Talbot formation. 



The influence of glaciation to the north is shown by the presence 

 of large ice-borne blocks within all parts of the terrace formations. 



The Talbot terrace is continued to the west of Chesapeake Bay 

 in the peninsula lying between the bay and the Potomac River. 

 This region is locally known as southern Maryland. 1 The lowest 

 terrace is fairly well developed from Baltimore south to the northern 

 end of Calvert County, Md., as a gently sloping front land rising 

 from water level to an altitude of 40 or 50 feet. Its shore line is 

 either low or defined by a wave-cut cliff of a few feet in height. 

 The terrace itself constitutes a slightly relieved plain with a gentle 

 slope toward tide water. r*rom this region south to the mouth of 

 the Patuxent River it is almost entirely wanting, having been cut 

 away by the active erosion of the waters of Chesapeake Bay. 



It is again developed along both shores of the Patuxent River to a 

 limited degree and much more extensively along the shores of the 

 estuarine portion of the Potomac River. In all of these localities it 

 forms the low front lands interruptedly bordering these estuaries. 



The origin of the materials of the Talbot formation in southern 

 Maryland is approximately the same as upon the Maryland-Delaware 

 Peninsula, although a larger proportion of material derived from 

 older Coastal Plain formation is incorporated. The succession of 

 materials is about the same and the base is marked by gravels and 

 coarse sand, while the present surface is formed by silt loam, loam, 

 and rather fine sandy coverings. Wherever this formation is well 

 drained, considerable areas of the Sassafras soils are encountered. 



The next higher terrace, the Wicomico, is rather sparingly de- 

 veloped in southern Maryland. It occurs at elevations ranging from 

 50 to 80 feet in the estuarine valleys and along the bay shore. Its 

 surface also rises with the gradient of some of the tributary streams 

 until elevations of 100 feet are attained near the Piedmont border. 



In general the surface of the Wicomico terrace is separated from 

 both the Talbot and Sunderland terraces by a distinct scarp. In 

 some instances the narrow remnants of the formation have been so 

 eroded that neither the flat surface nor the bounding scarps may be 

 readily distinguished. In almost all instances this formation occurs 

 as narrow, fragmentary benches of small area in this section of the 

 Coastal Plain. 



The materials entering into the composition of the Wicomico 

 terrace are chiefly gravel, sand, and the capping of loam or silt loam, 



1 See Patuxent, St. Marys, and Nomini Folios, U. S. Geol. Survey. 



