Glossary of Geographic and Oceanographic Terms

Land Features

Continent Large continuous area of land on the earths surface generally surrounded by water.

Island Body of land smaller than a continent that is surrounded by water. (Greenland is the largest island).

Isthmus Narrow section of land connecting two larger land areas, surrounded on two sides by water.

Peninsula Extension of land surrounded on three sides by water.

Mountain Range Continuous chain or series of mountains.

Plain Large, low, flat region of land.

Plateau Large area that is high and fairly flat.

Butte Isolated hill with steep sides, smaller than a plateau. Commonly found in the southwestern United States.

Mesa Similar to a plateau, but smaller in size: Flat on top, cliffs on the sides.

Valley Low area of land lying between hills of mountains.

Ice Cap Large area of ice several thousand feet thick covering either land or water.

Water Features

Ocean Large body of salt water generally bounded by continental land masses.

Sea Body of water smaller than an ocean lying within a continent or island group.

Gulf Large area of water partially surrounded by land.

Channel Narrow body of water lying between two areas of land.

Bay Small area of water surrounded by land on three sides and penetrating into the land.

Lake Smaller body of fresh water surrounded by land.

Strait Similar to channel.

Submarine Features

Basin Large circular depression on the ocean floor, generally 10,000 to 20,000 feet below sea level.

Ridge Submerged mountain chain. The largest are the mid ocean ridges which join together to form a feature 40,000 miles long.

Rift Sometimes found on the crest of a Ridge.

Rise A large elongated elevation lake a ridge but having less steep slopes.

Trench Long and narrow V-shaped depressions often found near a contnent or on the outside of island arcs.

Fracture Zone Zones of irregular topography thousands of miles long and about 100 miles wide, which separate large regions of the ocean floor having different depths or types of topography.

Continental Shelf Shallow marine terrace bordering the continents. The shelf deepens gradually to a depth of 600 feet about 50 miles from shore where a sudden increase in slope angle marks the top of the Continental Slope.

Continental Slope Slope from the outer edge of the Continental Shelf to the ocean basin.

Submarine Canyon Stee-sided gorge cut into the Continental Slope and Shelf thought to be cut by underwater flows of sediment called Turbidity Currents.

Seamount Submerged mountain, generally of volcanic origin, having at least 500 fathoms (3000 feet) of relief. Some seamounts, called guyots, have flat tops. They are submerged volcanic islands which had their tops smoothed by surf and erosion while they were above the surface.