Geology october 13 for exam 2

Geology october 13 for exam 2 - the remains of marine...

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Geology Coastal hazards- as population grows more and more people live in environmental areas. Coastal zones are critical environments -High population densities near coasts: approximately 70% of US population lives within 50 miles of saltwater coasts or the Great Lakes. -High energy zone where two major environments (oceanic, continental) interact. -Major processes and hazards: cyclonic storms (hurricanes and nor’easters), tidal floods, tsunamis, coastal erosion. People move to the coast in order to be close to recreational beaches Beaches are formed by wave action -As waves approach land they become over- steepened. -At depth of about ¼ wavelengths, the top goes faster than the bottom and it then breaks -The constant back and forth motion of the wave’s moves sand around. East coast beaches have a simple structure -US east coast beaches consist of sand that was eroded from the continent and brought to the ocean by rivers. -Other beaches can consist of locally derived pebbles and boulders or of
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Unformatted text preview: the remains of marine organisms (shells, etc,) When waves move from the open water toward the beach, the near shore end slows down by friction with the bottom ****The wave crest refracts (bends) toward the beach.-Refraction causes wave crests to become parallel to the shore. Wave refraction causes more intense wave action (erosion) on headlands and less intense waves (and depositions) in bays.-Headland erosion produces sea cliffs and stacks (remains of headland standing in the ocean). Longshore drift occurs when waves hit the shore at a slight angle and push sand grains along by a zigzag swash and backwash motion.-Longshore drift moves sand along the beach-Migrating sand trapped by a grain Longshore drift moves sand from north to south along the Atlantic coast-New sand is added to the system by rivers.-Sand is lost when it moves into deep water off the Gulf of Mexico. Migrating sand often forms barrier islands-Barrier islands are sand bars that lie parallel to the coast....
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Geology october 13 for exam 2 - the remains of marine...

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