Rocks and Landforms I- 5/I-6 Review for Quiz

Question What is the shape of most rivers? What is the shape of most rivers?

Answer Most rivers are curvy Most rivers are curvy

Question What do we call the sediment carried by a river? What do we call the sediment carried by a river?

Answer Sediment Load Sediment Load

Question What is the body of sediment that is deposited at the mouth of a river where it flows into the ocean? What is the body of sediment that is deposited at the mouth of a river where it flows into the ocean?

Answer Delta Delta

Question What kind of currents flow parallel to the beach? What kind of currents flow parallel to the beach?

Answer Longshore currents Longshore currents

Question What is the name of the structures that are designed to keep sand from moving into a ship channel and making the channel too shallow? What is the name of the structures that are designed to keep sand from moving into a ship channel and making the channel too shallow?

Answer Jetties Jetties

Question What is the name of the long, wall-like structures along beaches that extend into the ocean? What is the name of the long, wall-like structures along beaches that extend into the ocean?

Answer Groin Groin

Questsion Name the barriers built offshore to protect part of the shoreline. Name the barriers built offshore to protect part of the shoreline.

Answer Breakwater Breakwater

Question Name three structures built to prevent erosion along a shoreline. What is the particular pro & con for each structure? Name three structures built to prevent erosion along a shoreline. What is the particular pro & con for each structure?

Groins Pro – A longshore current loses speed as it meets the groin. This causes the current to deposit sand on the up-current side of the groin. This builds up the sand on the beach. Pro – A longshore current loses speed as it meets the groin. This causes the current to deposit sand on the up-current side of the groin. This builds up the sand on the beach.

Groins Con – Whenever sand on one beach increases, however; other beaches down-current lose a lot of sand Con – Whenever sand on one beach increases, however; other beaches down-current lose a lot of sand

Jetties Pro – designed to keep sand from moving into a ship channel and making it too shallow for ship traffic. Pro – designed to keep sand from moving into a ship channel and making it too shallow for ship traffic.

Jetties Con – sand will deposit elsewhere. Con – sand will deposit elsewhere. Con – often fail during especially large storms, and have to be rebuilt. Con – often fail during especially large storms, and have to be rebuilt.

Breakwaters Pro – act as a barrier to waves, preventing erosion and allowing the beach to grow. Pro – act as a barrier to waves, preventing erosion and allowing the beach to grow.

Breakwaters Con – the beach behind the breakwater often grows at the expense of the shoreline that is not protected Con – the beach behind the breakwater often grows at the expense of the shoreline that is not protected

Question What determines the different shapes of a delta? What determines the different shapes of a delta?

Answer Deltas have many different shapes, depending mainly on how strong the river is versus how strong the ocean waves and currents are. Deltas have many different shapes, depending mainly on how strong the river is versus how strong the ocean waves and currents are.

Deltas formed by large, strong rivers like the Mississippi, which empty into areas of the ocean where waves and currents are usually not too strong, form deltas with complicated shapes. Deltas formed by large, strong rivers like the Mississippi, which empty into areas of the ocean where waves and currents are usually not too strong, form deltas with complicated shapes.

If the ocean waves and currents are very strong compared to the river flow, the front of the delta becomes blunted or rounded off. If the ocean waves and currents are very strong compared to the river flow, the front of the delta becomes blunted or rounded off.

How a Groin Works