24 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
eastward the country gradually rises until it reaches an altitude of 
about 2500 feet above sea level, where it is genexally cut off by an 
escarpment facing to the southeast and about 1200 feet in height. 
The composite name of Cumberland- Allegheny - Catskill plateau 
would serve to define it, but for brevity I have designated the whole 
as the Cumberland plateau. Its general topographic character is 
that of a table land deeply cut by a system of ramifying drainage. 
At the north the surface is somewhat rolling, and the plateau ends 
at the south in long, finger-like spurs. Its rivers and streams rise 
generally near the edge of the escarpment and flow toward the 
northwest. The Potomac however breaks across the edge and flows 
eastward, while the New and Tennessee rivers enter the plateau 
from the east and flow westward. 7 
From the Cumberland plateau eastward to the eastern foot of 
the Blue Ridge lies a belt to which the name of Appalachian re- 
gion is applied in a restricted and definite sense. It is characterized 
by numerous long, narrow mountain ridges, closely parallel to 
each other and bending in sympathy with the local curvature 
of the belt. Through large areas they are approximately uniform 
in height, but elsewhere they are unequal. Ina notable belt, every- 
where recognized in the local nomenclature as a valley, and travers- 
ing the region from north to south, the ridges are so low that they 
rank only as hills. At the north the principal mountain area lies 
west of the great valley and only the Blue Ridge on the east. At 
the south the valley lies close to the Cumberland plateau, and the 
Blue Ridge is expanded into a broad mountain district, culminating 
in Mt. Mitchell (6711 feet), the a sii summit east of the Rocky 
Mountains. 
The remaining area is the Piedmont region, an undulating plain, 
diversified by low spurs from the mountain region, and occasional 
isolated hills of considerable elevation. The streams are rapid, and 
the topographic relief gradually diminishes toward the fall line. 
The communication was fully illustrated by maps and topographic 
sketches, and by a profile from Louisville, Kentucky, to Charleston, 
South Carolina. Remarks were made by Messrs. GILBERT, HARK- 
NEss and Cope. 
