1895] MARYLAND ACADEMY OF SCIENCES. 243 



Pennsylvania and Delaware, and it is separated from Virginia 

 by a line drawn from the Atlantic Ocean to the western bank 

 of the Potomac River and low water line on the Virginia shore, 

 this being the southern border of Maryland from the source 

 down. From the source of the Potomac a line runs north to 

 Mason and Dixon's line. The gross area of the state is 12,210 

 square miles: 9680 land; 1203, the Maryland part of the 

 Chesapeake ; 93, Assateague Bay ; and 1054, smaller estuaries 

 and rivers. 



The three leading topographical regions of the eastern por- 

 tion of the United States, viz., the Coastal Plain, the Pied- 

 mont Plateau, and the Apalachian region are all typically 

 represented within the limits of the state. The Coastal Plain, 

 or tide-water Maryland, forms the eastern portion, lying south 

 of a line drawn from Wilmington to Washington, through 

 Baltimore. This is closely outlined by the track of the Penn- 

 sylvania Railroad ; it covers about 5000 square miles. The 

 Eastern Shore, except in the extreme north, does not reach at 

 any point 100 feet in elevation, while most of it is below 25 

 feet. It is deeply cut up by tide- water rivers and bays. This 

 also describes the tract known as the "Necks" between Balti- 

 more and Havre de Grace. The temperature is much modified 

 by the surrounding water, the southern portion having a mean 

 annual temperature of 58 ; but the greater part lies between 

 56 and 54 ; the northern part averaging 52. Southern 

 Maryland or the Western Shore is different, considerable of it 

 reaches 100 feet, and in places as much as 180 feet. The mean 

 annual temperature seldom exceeds that of Baltimore, which is 

 55,6, by more than 2. 



The Piedmont Plateau, or Central Maryland, extends from 

 the Coastal Plain to the Catoctin Mountain, and has an area of 

 about 2500 square miles ; it is broken by low, undulating hills, 

 which gradually increase in elevation to the westward. Along 

 the eastern margin, heights exceeding 400 feet are frequently 

 reached, and at Catonsville 525 feet, while at Parr's Ridge, in 

 Carroll County, it rises above 850 feet. At Frederick City, 



