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 5,140 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