Moving Water• Most waves are caused by wind energy.• Tides are caused by the force of gravity.• Currents are caused by differences in salinity and water temperature, by winds, and by the angle of waves striking the shore.• Waves, some currents, and tides act on the features of the shoreline by causing erosion and deposition.• Deep ocean currents move water, but these currents do not usually cause erosion at the shore.
Waves• Ocean waves occur close to shore and in the deep ocean.• Ocean waves carry energy along the surface of the water.• Waves are mostly caused by wind energy.• In the deep ocean, waves cause water to rise and fall in a circular motion (not forward).• As waves move closer to the shore, the water through which they are traveling gets shallower and tumble onto the beach.• Strong waves can cause tremendous erosion and deposition when they reach the shore.
Currents• A current is a flow of water in a larger body of water.• In the deep ocean, water flows up and down in deep ocean currents. These currents occur because of differences in water temperature or salinity (amount of salt). These currents move and mix the ocean water, taking nutrients from the surface to living things below.• Surface currents are mostly caused by the wind moving over the ocean. These currents affect climate by moving heat energy around the Earth. Near the shore, these currents move water and eroded beach materials in the direction of the current’s flow.
Tides• Tides are the daily rising and falling in a regular of Earth’s waters.• Tides change the water level at most coasts in the world throughout the day.• Tides are caused mainly by the Moon’s gravity. The part of the Earth facing the moon and the part opposite experience high tide (ex: E and W). The other parts experience low tide at that time (ex: N and S).• Waves carry energy and cause water to tumble onto the shore. At high tide waves hit the highest and at low tide the lowest.