Coast and Beach (Encyclopedia of Science)
The coast and beach, where the continents meet the ocean, are everchanging environments where the conflicting processes of erosion (wearing away) and sedimentation (building up) take place. Coast is the land that borders an ocean or large body of water. Beach refers to a much smaller land region, usually just the area directly affected by wave action.
Coasts are generally classified into two types: emergent and submergent. Emergent coasts are those that are formed when sea level declines. Areas that were once covered by the sea emerge and form part of the landscape. This new land area, which was once protected underwater, is now attacked by waves and eroded. If the new land is a cliff, waves may undercut it, eventually causing the top portions of the cliff to fall into the sea. When this happens, the beach is extended at its base. Along emergent coast shorelines the water level is quite shallow for some distance offshore. Much of the coast along California is emergent coast.
Submergent coasts are those that are formed when sea level rises, flooding formerly exposed land areas. Valleys near coastal areas that had been carved out by rivers become estuaries, or arms of the sea that extend inland to meet the mouth of a river, for example, Chesapeake Bay in Virginia and Maryland. Hilly terrains become collections of islands, such as those off...
(The entire section is 628 words.)
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