10.1 Shoreline Erosion and Deposition

Where does sand come from?

Sand Rock broken down into smaller pieces. Shoreline The place where land and a body of water meet.

Erosion

Wave Energy Waves – when wind moves across the ocean making a disturbance.

Wave Trains Waves that move in groups. Wave period – the period of time waves in the wave train are separated. Surf – Breaking waves

The Pounding Surf Energy of the waves crashing break rock. Broken rock is thrown to shore creating sand. Waves pick up the sand and break down pieces even smaller.

How do waves break rocks? Energy is released by crashing waves. This energy breaks rocks. Water form breaking waves also rushes into cracks in rocks, which helps break rock and washes away fine grains of sand.

Wave Erosion Sea cliffs – waves erode and undercut rock to make steep slope. Sea stacks – offshore columns of resistant rock that were once connected to the mainland. Sea Caves-waves cut large holes into fractured or weak rock along the base of sea cliffs. Sea Arches – wave action erodes sea caves until arches are cut through the caves.

Waves

Explain why large waves are more able to remove large chunks of rock from a shoreline than average-sized waves are. Large waves are more able to remove large chunks of rock from a shoreline than average-sized waves are because large waves transfer more energy than average-sized waves do.

Beach Any area of shoreline that is made up of material deposited by waves.

Shore Current Undertow – the movement of water carries pieces of sand and rock away from the shore.

Longshore current The current where water travels parallel to the shoreline very near shore. Waves hit the shore at an angle.

How do longshore currents move sand? Waves break at oblique angles to the shore. Waves wash sand parallel to the direction they break. Return water flow brings sand directly down the slope of the beach. This process results in a zigzag pattern of sand movement.

Offshore Deposits Materials are transported off shore.

An underwater or exposed ridge of sand, gravel, or shell material. Sandbar An underwater or exposed ridge of sand, gravel, or shell material.

An exposed sandbar that is connected to the shoreline. Barrier spit An exposed sandbar that is connected to the shoreline.

Barrier island A long, narrow island usually made of sand that forms parallel to the shoreline a short distance offshore.

Review Questions How do wave deposits affect a shoreline? Wave deposits often form beaches along shorelines. Describe how sand moves along a beach. Because waves strike shorelines at an angle, sand moves along beaches in zigzag patterns. How can the energy of water waves affect a shoreline? The energy from water waves can erode a shoreline

Review quiz 10.1 Sandbar Sea arch Beach Sea stack Sea cliff Sea cave Surf Undertow Wave period shoreline Sea arch Sea stack Sea cave Wave Wave train Sand Longshore current