Ocean Currents and Their Causes

What are the two general types of dynamic beach response to wave motion?

Response to normal conditions and response to storm conditions

What is an inlet in the context of dynamic beach response?

It is the narrow opening between the lagoon and the sea.

How does the beach recover from storm attacks?

The wave transports sand from the offshore bar built during the storm and places the material on the beach.

What is the role of normal wave conditions in beach recovery?

Normal wave conditions transport sand from offshore bars back to the beach. Signup and view all the answers

Why does full recovery of the beach sometimes not occur after a storm?

Sand is deposited too far offshore during the storm to be returned to the beach by normal wave conditions. Signup and view all the answers

What happens to the beach and dune during storm conditions?

During storm conditions, the coast may need to sacrifice large sections of beach and dune. Signup and view all the answers

What causes the creation of longshore currents?

Waves approaching the beach at an angle Signup and view all the answers

What is a rip current?

When longshore current flows seaward under certain conditions Signup and view all the answers

How are surface currents created?

Wind blowing over the surface of the water Signup and view all the answers

What causes the formation of storm surge?

Strong winds creating a pile-up of water against a barrier Signup and view all the answers

What are tsunamis and how are they typically generated?

Waves created by earthquakes or tectonic disturbances on the ocean bottom Signup and view all the answers

Where do the forces of the sea most directly impact?

Beach and nearshore zone regions Signup and view all the answers

What are some characteristics used to describe beaches?

Average size of sand particles, range and distribution of sizes, sand composition, elevation and width of berm, slope or steepness of the foreshore, the existence of a bar, and the general slopes of the inshore zone fronting the beach. Signup and view all the answers

What type of sediments are usually absent on ocean beaches?

Clays and silt. Signup and view all the answers

What is a barrier island?

Long narrow island or spits laying parallel to the mainland. Signup and view all the answers

What is the composition of beach sediment at the Boston Science Museum Wave Flume?

Ranges from fine sand to cobbles, including weathered mountain rocks (sand), fragments of coastal formation, sediment from deeper water, marine shell fragments, coral reef fragment, and volcano material. Signup and view all the answers

What is a tombolo?

A deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Signup and view all the answers

What are lagoons and how are they connected to the sea?

Lagoons are shallow bodies of water separating the barrier beach from the mainland. They are usually connected to the sea by narrow channels through tidal current flow. Signup and view all the answers

How do inlets affect adjacent shores?

By interrupting longshore transport and trapping onshore-offshore moving sand. Signup and view all the answers

What happens to sand during ebb-tide near inlets?

Sand transport to the inlet by wave is carried seaward and deposited on an outer bar. Signup and view all the answers

What occurs during floodtide near inlets?

Sand in the inlet is carried into the lagoon and deposited, creating inner bars. Signup and view all the answers

How do tidal inlets impact sand supply to adjacent shores?

Tidal inlets store sand and reduce the supply of sand to adjacent shores. Signup and view all the answers

What defines the long-range condition of a beach?

The rate of supply and loss of littoral material (sediment). Signup and view all the answers

Why is conservation of sand important for shore protection?

Conservation of sand is crucial to maintaining stable beaches. Signup and view all the answers

What natural processes erode the beach and transport material shoreward?

Waves and overflowing water Signup and view all the answers

What is the significant cause of erosion on a beach resulting from wind action?

Deflation Signup and view all the answers

How is sand transported alongshore by waves breaking at an angle to the shore?

Longshore Sediment Transport Signup and view all the answers

What is the importance of the sorting of beach sediment by wave action?

Selective redistribution of sediment particles along a beach profile Signup and view all the answers

Why is it important to use fill material similar in grain-size distribution to the native beach material in beach nourishment projects?

To balance the selective loss of finer material to the offshore region Signup and view all the answers

What is one of the man-induced causes of beach erosion mentioned in the passage?

Land Subsidence from Removal of Subsurface Resources Signup and view all the answers