Chapter 10

Why does the crust subside slightly on either side of a melting glacier?

Crust under the glacier rises as the ice melts. This allows mantle on either side of the glacier to move to areas under the glacier.

Features of a depositional coast may include spits, barrier islands, tombolos, and __________.

Deltas

Alternatives to hard stabilization to protect coastlines from erosion including construction restrictions, relocation of structures, and construction of seawalls. T/F

F

Erosional coasts are characterized by features of accumulated sand/pebble/rock that are eroded elsewhere and deposited on shore where longshore currents slow. T/F

False

Seawalls are quite effective at controlling beach erosion. T/F

False

The nearshore is equivalent to the intertidal zone. T/F

False

Of the following statements about groins, which is/are true?

Groins can be singular or many. Groins can be constructed out of large blocky rocky material (rip-rap) or of sturdy wood pilings.

Why does the crust uplift slightly on either side of a growing glacier?

Mantle under the glacier is pushed aside by sinking crust. This mantle pushes up the crust on either side of the glacier.

A. formation of large inland lakes B. increased seafloor spreading rates C. melting glacial ice D. melting sea ice E. uplifted continental crust

Melting Sea Ice

In the long term, what do beach drift and longshore current do?

Move sediment parallel to the shoreline

What would you do to both grow a large beach and protect a harbor mouth?

Place two jetties on either side of the harbor mouth, and build a breakwater upcurrent from the harbor mouth.

How are changes in sea level recorded in rock?

Rock type changes vertically.

How would you expect sediment to change as you walk from shore into the ocean?

Sediment generally changes from sand to mud to limestone.

A spit is a coastal feature of sand deposited in the direction of the longshore drift from shore toward deeper water into the mouth of a bay. T/F

T

Eustatic changes in sea level refer to worldwide changes in the volume of seawater or in the volume of the ocean basins. T/F

T

Sea caves and sea stacks are more likely to occur in an area with hard bedrock. T/F

T

What will happen to the crust as a glacier grows?

The crust under the glacier will sink into the mantle.

How would a beach be affected if a wide berm were protected from erosion during winter months?

The wintertime beach would look similar to the summertime beach.

A. marine terrace B. sea arches C. sea caves D. tombolo E. wave-cut cliffs

Tombolo

A summer recreational beach typically has more sediment on it than a winter recreational beach.T/F

True

The Gulf coast of the United States is an example of a coast where tectonic subsidence is occurs. T/F

True

The longshore current is caused by waves striking the beach at an angle. T/F

True

If one were to walk from the ocean landward across a barrier island complex, in which order would one encounter the following environments?

beach, dune, barrier flat, high marsh, low marsh

Large deposits of sediment at the mouths of rivers are called:

deltas.

barrier island

depositional shore

spit

depositional shore

The rate of wave erosion along a coastline is determined by all of the following except the:

direction of the longshore current.

Which of the following pairs does not belong together?

emerging shorelines: drowned beaches

wave-cut cliffs

erosional shore

longshore current

flows parallel to shore within surf zone

The section of the coast that is exposed at low tide and submerged at high tide is called the

foreshore.

Which rock types would you expect to be deposited on top of limestone if sea level rises and then falls?

limestone followed by mud

Eroded material is carried along coastlines from high wave-energy areas to:

low wave-energy areas.

offshore

beyond the low-tide breakers

Which of the following structures are types of coastal stabilization structures?

breakwaters jetties groins

How do jetties protect harbor entrances?

by inhibiting the deposition of sand in the harbor mouth

The primary drawback of beach nourishment as a remedy for beach erosion is __________.

cost

Which of the following landforms shows the least amount of erosion along U.S. coasts?

crystalline bedrock of New England

Southern California beaches would have more sand if __________.

dams were removed from streams flowing to the coast

All of the following are typically characteristic of depositional shores except:

marine terraces.

Submerging shorelines might have all of the following characteristics except:

marine terraces.

Nor'easters affect which area of the U.S. coastline during the fall and winter months?

northern Atlantic coast

Along U.S. coasts, a drop in sea level can be noted at __________.

northern Maine

In which direction does the longshore current move?

parallel to shore

Which rock types would you expect to see deposited if sea level rises and then falls?

sand covered by mud covered by sand

All of the following are alternatives to hard stabilization except:

seawalls.

What is isostasy?

the rising and sinking of Earth's crust relative to the mantle in response to the redistribution of mass on the surface

For how long will land rebound after a glacier melts?

thousands of years

Why are coastal stabilization structures built along coastlines?

to stop beach sand erosion to protect coastal property from wave erosion

What is the longshore current?

water forced by waves to move along the shore

Of the following conditions, which result in the accumulation of sand on the berm, thereby making the berm wider?

-higher beach infiltration rates -a beach dominated by swash -light wave activity

Of the following features or conditions, which is/are related to emerging shorelines?

ALL BUT Submerged river valleys

Of the following statements about global sea level, which is/are true?

ALL BUT When the rate of sea floor spreading increases, global sea level is lowered.

Which of the following is designed to prevent or retard shoreline erosion?

All of these are used to try to prevent or retard shoreline erosion

In general, what do beaches look like at the end of winter?

Beaches tend to have a narrow berm and a prominent longshore bar.

In general, what do beaches look like at the end of summer?

Beaches tend to have a wide berm and no longshore bar.

Why does glacial subsidence NOT occur at the exact moment that a glacier forms?

The rate of subsidence is controlled by the rate at which mantle can flow.

How are winter beaches different from summer beaches?

Winter waves are short and high, whereas summer waves are long and shallower.

Of the following characteristics or features, which is/are associated with erosional shores?

a coastline with lots of rugged headlands tectonic activity wave-cut benches and marine terraces rocky coasts

How long does it take berms to become narrow and rocky after summer has passed?

a few weeks

Winter beaches:

are narrower than summer beaches due to high-energy waves during the winter

Which way would sediment move if NO beach drift existed?

at an angle to shore

Southern California beaches in winter typically are narrow and rocky. That is because __________.

heavy winter wave activity moves the sand out to the longshore bar and uncovers the rocks underneath the sand

Eustatic changes in sea level might include:

increased glacial melting due to the global warming.

The particle size on a beach:

is related to whatever material is locally available.