me mountains; narrow,
discontinuous coastal plain

American Samoa
five volcanic islands with rugged peaks and limited
coastal plains, two coral atolls (Rose Island, Swains Island)

Andorra
rugged mountains dissected by narrow valleys

Angola
narrow coastal plain rises abruptly to vast interior plateau

Anguilla
flat and low-lying island of coral and limestone

Antarctica
about 98% thick continental ice sheet and 2% barren rock,
with average elevations between 2,000 and 4,000 meters; mountain
ranges up to nearly 5,000 meters; ice-free coastal areas include
parts of southern Victoria Land, Wilkes Land, the Antarctic
Peninsula area, and parts of Ross Island on McMurdo Sound; glaciers
form ice shelves along about half of the coastline, and floating ice
shelves constitute 11% of the area of the continent

Antigua and Barbuda
mostly low-lying limestone and coral islands,
with some higher volcanic areas

Arctic Ocean
central surface covered by a perennial drifting polar
icepack that averages about 3 meters in thickness, although pressure
ridges may be three times that size; clockwise drift pattern in the
Beaufort Gyral Stream, but nearly straight-line movement from the
New Siberian Islands (Russia) to Denmark Strait (between Greenland
and Iceland); the icepack is surrounded by open seas during the
summer, but more than doubles in size during the winter and extends
to the encircling landmasses; the ocean floor is about 50%
continental shelf (highest percentage of any ocean) with the
remainder a central basin interrupted by three submarine ridges
(Alpha Cordillera, Nansen Cordillera, and Lomonosov Ridge)

Argentina
rich plains of the Pampas in northern half, flat to
rolling plateau of Patagonia in south, rugged Andes along western
border

Armenia
Armenian Highland with mountains; little forest land; fast
flowing rivers; good soil in Aras River valley

Aruba
flat with a few hills; scant vegetation

Ashmore and Cartier Islands
low with sand and coral

Atlantic Ocean
surface usually covered with sea ice in Labrador Sea,
Denmark Strait, and coastal portions of the Baltic Sea from October
to June; clockwise warm-water gyre (broad, circular system of
currents) in the northern Atlantic, counterclockwise warm-water gyre
in the southern Atlantic; the ocean floor is dominated by the
Mid-Atlantic Ridge, a rugged north-south centerline fo