50 THE PLANT LIFE OF MARYLAND 



Coastal Plain portions of Harford and Baltimore counties and a 

 few places on the shore of Anne Arundel County are relatively level 

 at elevations of 20 ft. or less, being in the Talbot formation; so also 

 are portions of the interior in Charles and Prince George's counties 

 at elevations of 100 to 120 ft., being in the Lafayette formation. It 

 is in the southernmost part of the Chesapeake-Potomac peninsula, 

 and particularly in the neighborhood of the estuaries that the 

 topography is most sharply dissected. In almost all localities about 

 the heads of estuaries there is a sharp rise from tide-level to eleva- 

 tions of 100 to 140 ft., while along the Bay side of Calvert County 

 there is a series of bluffs GO to SO ft. in height. The initial state 

 of the topography is revealed in the flat divides which lie between 

 the heads of the smaller streams, as in the neighborhood of Brandy- 

 wine in Prince George's County. 



The larger streams which traverse this area, the Patuxent, 

 Patapsco and Gunpowder, rise in the Piedmont, while a number of 

 the smaller streams, the Wicomico, the Severn and the Magothy, 

 rise in the Coastal Plain. All of the larger streams merge into 

 estnaries, which are in general shorter and more abrupt in their 

 termination than those of the Eastern Shore. Consequent upon the 

 character of the topography there is a much less development of 

 marshes and swamps along the estuaries and streams than is the 

 case "ii the Eastern Shore. Marshes are most extensive about 

 Spesutie Island and southward along the Bay shore of Harford 

 County. While there are no upland swamps the Western Shore 

 district has the only typical peat bogs in the state outside the Moun- 

 tain Zone. 



The Midland Zone; Lower Midland District. — The Lower .Mid- 

 land District comprises the northern half of Cecil County, the 

 greater parts of Harford, Baltimore, Howard and Montgomery 

 comities, and a portion of Carroll. It is underlaid by Crystalline 

 rocks, mostly of a character very resistant to weathering. The 

 topography of the region may be stated in general terms as being 

 that of a maturely dissected peneplain. The gently rolling plateaus 

 descend to the streams at first gently, then abruptly, there often 

 being outcrops of rock adjacent to the streams. The maximum ele- 



