MARYLAND GEOLOGICAL SURVEY 145

Ocean, and those which find their outlet by less direct courses
through the St. Lawrence and Mississippi basins.. South of New York
the Appalachian Region is divided into three more or less clearly
defined districts. The eastern district is composed of ranges of mount-
ains known in Pennsylvania by the name of the South Mountains,
but in Maryland, Virginia and North Carolina commonly by the
name of the Blue Ridge. South of Virginia this eastern belt in-
creases in width, and in North Carolina contains the most lofty points
in the whole Appalachian system. Along the western border of the
Blue Ridge district lies the Great Valley, which in Pennsylvania is
about ten miles in width but which broadens southward, attaining in
Virginia for a distance of 300 miles a nearly uniform width of twenty
miles. It forms one of the richest agricultural belts within the Appa-
lachian Region. The central district is known as the Appalachian
Region proper, and is characterized by parallel even-topped ranges
throughout the whole length of the mountainous area. The con-
tinuity of these ranges is frequently interrupted, and sharp ridges and
deep valleys everywhere abound. The western district is character-
ized by undulating ranges which rise from a high plateau that grad-
ually decreases in elevation westward until it merges imperceptibly
into the rolling country of the Mississippi Valley. Along the eastern
side of this western district are the Alleghany Mountains, in which the
parallel ridges so characteristic of the whole Appalachian Region are
preserved. The streams everywhere flow with rapid currents and are
extremely variable in the volume of water which they carry.

Let us now turn our attention to a consideration of the Maryland
area the three regions of which have been above outlined, viz., the
Coastal Plain, the Piedmont Plateau and the Appalachian Region.
All are typically represented within the area of the state of Mary-
land and have conditioned to a marked extent its economic develop-
ment.

THE COASTAL PLAIN.

The Coastal Plain embraces the eastern portion of Maryland and
includes the area between the Atlantic Ocean on the east and a line
passing northeast to southwest from Wilmington to Washington