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Firth is an arm of the sea or the opening of a river into the sea. The term is used mostly in Scotland, where many rivers open into firths. Firths are similar to fiords. But most fiords have high walls, and the walls of firths may be low. See also Fiord.
Ocean is the great body of water that covers nearly 71 percent of Earth's surface. People also call it the sea. The ocean contains 97 percent of… More>>
Cliff is a steep face of rock. Many processes of erosion form cliffs. Waves cut imposing and scenic cliffs along coastlines. Rivers create deep… More>>
Sea level is the level of the ocean's surface. It changes continuously with the tides, and it varies from one part of the world to another. Mean… More>>
Geyser, GY zuhr, is a spring that throws up hot water with explosive force from time to time. Often, the water shoots up in great columns, cloudy… More>>
Ice formation is a large mass of frozen water. Ice formations include glaciers, icebergs, and sea ice.
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Fiord 
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