EM 1110-2-1100 (Part I)
30 Apr 02
N
CANADA
Igneous bedrock bluffs, rocky islands, short
Boston
spits, tidal estuaries, glacial drumlins, high
tide range
Reworked till bluffs, short barriers,
estuaries, glacial moraine islands
New York
Delaware Bay
Chesapeake Bay
Barriers with open water ponds
Large bays (Chesapeake, Delaware)
ATLANTIC OCEAN
Charleston
Barriers backed by salt marsh
Numerous inlets (Georgia Bight)
Limestone reef outcrops (Florida)
Carbonate (coral) with
mangrove in protected areas
600
0
600
1200 Kilometers
Figure I-2-1. Atlantic coast characteristics
result of erosion by the glaciers. Uplifted terraces may be common along these coasts that were formerly
weighted down by ice. Abrupt changes in coastal character occur where glacial deposits and particularly
glacial outwash play a dominant role, while in some rocky areas, few glacial erosion forms can be found.
Moraines, drumlins, and sand dunes, the result of reworking outwash deposits, are common features.
Glaciated coasts in North America extend from the New York City area north to the Canadian Arctic (Figures
I-2-3, I-2-4, IV-2-8, and IV-2-9), on the west coast, from Seattle, Washington, north to the Aleutian Islands,
and in the Great Lakes. (Figure IV-2-20) (Shepard 1982).
b. Atlantic Central and South: Barrier and drowned valley coasts. South of the glacial areas begins
the coastal Atlantic plain, featuring almost continuous barriers interrupted by inlets and by large embayments
with dendritic drowned river valleys, the largest being Delaware and Chesapeake Bays. The North American
coastline is reported to include over 10,000 km of barriers, about 33 percent of all barrier coast of the world
(Berryhill, Dixon, and Holmes 1969). The United States alone has a total length of 4,900 km of barriers and
spits, the longest extent for a single nation (Figure I-2-5 and Table IV-2-3). Extensive wetlands and marshes
I-2-2
Coastal Diversity
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