Agents of Erosion & Deposition

1. Agents of Erosion & Deposition Shoreline Erosion & Deposition

2. Wave Energy • Wave Trains • Waves travel in groups called wave trains. • As wave trains move away from their source, they travel through the ocean water uninterrupted. • When the waves reach the shallow water, the bottom of the wave drags against the sear floor, slowing the wave down. • The upper part of the wave moves more rapidly and grows taller. When the top of the wave becomes so tall that it cannot support itself, it begins to curl and break. • These breaking waves are known as surf.

3. Wave Energy Cont. • The Pounding Surf • A tremendous amount of energy is released when waves break. • A crashing wave can break solid rock and throw broken rocks back against the shore. • The loose sand picked up by waves wears down and polishes coastal rocks. • Rock is broken down into smaller and smaller pieces that eventually become sand.

4. Wave Erosion • Wave erosion produces a variety of features along a shoreline. • Sea cliffs are formed when waves erode and undercut rock to produce steep slopes. • Shaping a Shoreline • Much of the erosion responsible for landforms you might see along the shoreline takes place during storms. • Large waves generated by storms release far more energy than normal waves do.

5. Shoreline Features Created by Wave Erosion • Sea Stacks • Offshore columns of resistant rock that were once connected to the mainland. • Sea Arches • Form when wave action continues to erode a sea cave, cutting completely through the rock. • Sea Caves • Form when waves cut large holes into fractured or weak rock along the base of sea cliffs.

6. Headlands • Finger shaped projections that form when cliffs made of hard rock erode more slowly than surrounding rock. • Sea Cliffs • Formed when waves erode and undercut rock to produce steep slopes. • Wave-Cut Terraces • Form when a sea cliff is worn back, producing a nearly level platform beneath the water at the base of the cliff.

7. Wave Deposits • Beaches • Any area of the shoreline made up of material deposited by waves. • Light colored sand is most common beach material. • Black sand beaches in Hawaii are made of eroded volcanic lava. • Wave Angle and Sand Movement • Most waves approach the beach at a slight angle and retreat in a direction more perpendicular to the shore. • This movement of water is called a longshore current. • Offshore Deposits • When waves erode material from the shoreline, longshore currents can transport and deposit this material offshore, which creates landforms in open water.