Washington County is very flat and not very high above sea level.
The county is, in fact, a seabed that is temporarily not covered by
the ocean. In the past, the county has been covered and uncovered by
the ocean many times. Some of the rise and fall in sea level has
been due to changes in the ocean volume, but most has been caused by
continental glaciers, vast ice sheets a mile or more thick that
covered much of North America. For millions of years, the earth has
undergone cycles of glacier formation followed by periods of glacier
melting. Sea level becomes lower when the glaciers form and sea
level rises when the glaciers melt.
In eastern North Carolina, the western advance of the sea during
each melting of the glaciers is marked by a sand ridge called a
"scarp". The land to the east of each scarp is called a
"terrace". The scarps and terraces occur at lower elevations and
are younger from west to east. Most of Washington County is on the
youngest marine terrace, called the Pamlico Terrace. The western
boundary of the Pamlico Terrace is the Suffolk Scarp, a sand ridge
complex that extends from Suffolk, Virginia, through Washington
County, to near Morehead City. There are two scarps in Washington
County. The older scarp is called the Walterboro Scarp. Long Ridge
Road follows the Walterboro Scarp sand ridge from Plymouth to
Pinetown. The elevation at the foot of this scarp is about 40 feet
above sea level, and the ocean most likely reached here several
hundred thousand years ago.
The Suffolk Scarp is the youngest scarp in the county. Highway 32
follows it from Plymouth to Acre Station. The elevation at the foot
of the Suffolk Scarp is about 20 feet above sea level. During the
last warming period between glaciers, about 70,000 years ago, the
oceanfront was at the Suffolk Scarp. The Outer Banks ran through
Washington County 70,000 years ago. At that time, Van Swamp was a
back-dune flats area behind the barrier islands. There was an inlet
where Van Swamp drains across highway 32. The climate was warm and
the vegetation was tropical.
While the ocean was at the Suffolk Scarp, the glaciers again began
to grow and there was another ice age (called the Wisconsin glacial
age) which reached its peak about 18,000 years ago. Continental
glaciers covered North America as far south as Pennsylvania. Sea
level fell as water was tied up in the glaciers, and present-day
Washington County found itself 400 feet above sea level. The ocean
shoreline was many miles further east of its present location. The
Roanoke River ran to the sea through a broad river valley that is
now Albemarle Sound, and most of Pamlico Sound was dry land. The
climate was cold and the vegetation was similar to present-day
Canada. Strange animals such as the mammoth, musk ox, and mastodon
(Beyer, 1991) roamed the area. Again the glaciers began to melt and
sea level began to rise. The coastline has been migrating westward
ever since. Rising sea level has filled the Roanoke River valley
with water and formed the Albemarle Sound.
Sea level is still rising, causing shoreline erosion along the sound
and river and increasing drainage problems in the eastern part of
the county. Sea level is now estimated to be rising about one foot
each 50-100 years. Counties to the east of us are struggling to cope
with saltwater intrusion and poor drainage. In Washington County,
the town of Creswell and some farmland along the Scuppernong River
require pump-assisted drainage. Unless the melting of the glaciers
stops, Washington County will one day be reclaimed by the sea.