Oce 1001 Exam 3 Ch 10

24 July 2022
4.7 (114 reviews)
80 test answers

Unlock all answers in this set

Unlock answers (76)
question
The correct order of beach features as you move from the coast toward offshore is
answer
berm, beach face, longshore trough, longshore bar
question
The section of the coast that is exposed at low tide and submerged at high tide is called the
answer
foreshore
question
The particle size on a beach
answer
is related to whatever material is locally available
question
Beach joggers prefer to run on the _________
answer
beachface
question
True statements about coastal regions and landforms
answer
The area of a beach above the shoreline is often called the recreational beach. The berm is located in the backshore area. The berm is affected by storm waves but is typically dry and relatively flat. Most of the beach face is exposed during the lowest tides and covered during the highest tides. The beach face is the wet, sloping surface in the foreshore area.
question
Wave refraction is __________.
answer
the bending of waves
question
What causes wave refraction?
answer
The part of a wave in shallow water slows down, causing the wave to bend and line up nearly parallel to the shore.
question
Most of the year, and most of the time, the movement of sediment and water (longshore current) along the California coast is from
answer
North to South
question
What is the most obvious difference between summertime and wintertime beaches?
answer
during summertime there is much more sand on the beach
question
Why does the beach shown in the video look the way that it does during summertime?
answer
Small waves move sand up the beach face and create a wide, sandy beach.
question
Why does the beach in the video look the way that it does during wintertime?
answer
Large waves move sand offshore onto longshore sand bars and create a rocky beach.
question
Normally, beaches have the greatest amount of sand on the berm near the end of
answer
Summer
question
In the long term, what do beach drift and longshore current do?
answer
Move sediment parallel to the shoreline
question
What is the longshore current?
answer
water forced by waves to move along the shore
question
Which way would sediment move if NO beach drift existed?
answer
at an angle to shore
question
Southern California beaches in winter typically are narrow and rocky. That is because __________
answer
heavy winter wave activity moves the sand out to the longshore bar and uncovers the rocks underneath the sand
question
which result in the accumulation of sand on the berm, thereby making the berm wider?
answer
Higher beach infiltration rates A beach dominated by swash Light wave activity (small waves)
question
The velocity of the longshore current will be higher when wave heights are higher.
answer
True
question
A summer recreational beach typically has more sediment on it than a winter recreational beach.
answer
True
question
which help(s) form a well-developed delta?
answer
Low rates of erosion High sediment load High rates of deposition Small wave energy A large-volume river
question
Southern California beaches would have more sand if __________.
answer
dams were removed from streams flowing to the coast
question
Conditions favorable for the existence of barrier islands occur in the United States __________
answer
on the Atlantic and Gulf coasts
question
The area of the barrier island complex that would contain thickets and woodlands would be the
answer
barrier flat
question
If one were to walk from the ocean landward across a barrier island complex, in which order would one encounter the following environments?
answer
beach, dune, barrier flat, high marsh, low marsh
question
Narrow currents flowing across the surf zone toward the open ocean are called
answer
rip currents
question
Sea caves and sea stacks are more likely to occur in an area with hard bedrock
answer
True
question
Which feature of barrier islands provides evidence for a rise in sea level?
answer
A peat outcrop
question
How does the tide cycle affect erosion along a sea coast?
answer
The tide cycle causes erosion to occur at different elevations along a sea coast.
question
How is a cave created in a cliff face along a sea coast?
answer
Wave action erodes areas of weakness in rock in a sea cliff.
question
How is an arch formed along a sea coast?
answer
An arch forms when a sea cave breaks through a headland or where two sea caves coalesce as they erode back due to wave action.
question
How does a sea stack form?
answer
A stack forms when a sea arch collapses, leaving a vertical column of rock offshore.
question
What is isostasy?
answer
the rising and sinking of Earth's crust relative to the mantle in response to the redistribution of mass on the surface
question
Why does the crust uplift slightly on either side of a growing glacier?
answer
Mantle under the glacier is pushed aside by sinking crust. This mantle pushes up the crust on either side of the glacier.
question
Why does the crust subside slightly on either side of a melting glacier?
answer
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.
question
For how long will land rebound after a glacier melts?
answer
thousands of years
question
Why does glacial subsidence NOT occur at the exact moment that a glacier forms?
answer
The rate of subsidence is controlled by the rate at which mantle can flow.
question
Geologic evidence suggests that eustatic (global) sea level rises have been caused by __________.
answer
rapid seafloor spreading at divergent plate boundaries
question
Eustatic changes in sea level might include:
answer
increased glacial melting due to the global warming.
question
An increase in the spreading rate at a mid-ocean ridge will cause a decrease in sea level.
answer
False
question
True statements about global sea level
answer
Sea level has risen about 120 meters (400 feet) in the past 18,000 years. When seawater cools, it contracts and occupies less volume, so global sea level is lowered. Sea level is affected by the amount of ice in polar ice caps on land. When seawater warms, it thermally expands and occupies more volume, so global sea level rises.
question
Nor'easters affect which area of the U.S. coastline during the fall and winter months?
answer
northern Atlantic coast
question
Along U.S. coasts, a drop in sea level can be noted at __________.
answer
Northern Maine
question
The Gulf coast of the United States is an example of a coast where tectonic subsidence occurs.
answer
True
question
Why are coastal stabilization structures built along coastlines?
answer
to protect coastal property from wave erosion & to stop beach sand erosion
question
In which direction does the longshore current move?
answer
parallel to shore
question
Which of the following structures are types of coastal stabilization structures?
answer
breakwaters, jetties & groins
question
How do jetties protect harbor entrances?
answer
by inhibiting the deposition of sand in the harbor mouth
question
What would you do to both grow a large beach and protect a harbor mouth?
answer
Place two jetties on either side of the harbor mouth, and build a breakwater upcurrent from the harbor mouth.
question
A friend is considering purchasing a vacation home on a barrier island. Given what you've learned about the impact of waves on coastal landforms, what information and advice could you offer your friend?
answer
Barrier islands tend to experience a good deal of sand erosion and deposition, and mitigating these effects is extremely difficult. Your friend would be wise to reconsider & A home on a barrier island is likely to take the full brunt of storm waves, making it a risky proposition. Your friend should think twice before purchasing.
question
The primary drawback of beach nourishment as a remedy for beach erosion is __________
answer
cost
question
In terms of erosion protection from wave action, seawalls:
answer
lead to erosion of sediment on their seaward sides
question
You are an engineer assigned to design a solution to protect a historic landmark threatened by coastal erosion. What scenario would have the least impact on natural coastal processes and be the most cost effective?
answer
relocate the structure
question
How would you expect sediment to change as you walk from shore into the ocean?
answer
Sediment generally changes from sand to mud to limestone
question
How are changes in sea level recorded in rock?
answer
Rock type changes vertically.
question
Which rock types would you expect to be deposited on top of limestone if sea level falls and then rises?
answer
mud followed by limestone
question
Which rock types would you expect to be deposited on top of limestone if sea level rises and then falls?
answer
limestone followed by mud
question
Which rock types would you expect to see deposited if sea level rises and then falls?
answer
sand covered by mud covered by sand
question
Winter beaches
answer
are narrower than summer beaches due to high-energy waves during the winter
question
True characteristics or features, which is/are associated with erosional shores?
answer
A coastline with lots of rugged headlands, Rocky coasts, Wave-cut benches and marine terraces, Tectonic activity
question
Large deposits of sediment at the mouths of rivers
answer
deltas
question
Eroded material is carried along coastlines from high wave-energy areas to
answer
low wave-energy areas
question
Sediment is supplied to the coastal zone by:
answer
rivers. local biological activity. coastal erosion.
question
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.
answer
True
question
Seawalls are quite effective at controlling beach erosion.
answer
False
question
Alternatives to hard stabilization to protect coastlines from erosion include construction restrictions, relocation of structures, and construction of seawalls
answer
False
question
In general, what do beaches look like in the end of winter?
answer
Beaches tend to have a narrow berm and a prominent longshore bar.
question
How are winter beaches different from summer beaches?
answer
Winter waves are short and high, whereas summer waves are long and shallower.
question
In general, what do beaches look like at the end of summer?
answer
Beaches tend to have a wide berm and no longshore bar.
question
How long does it take berms to become narrow and rocky after summer has passed?
answer
A few weeks
question
How would a beach be affected if a wide berm were protected from erosion during winter months?
answer
The wintertime beach would look similar to the summertime beach.
question
longshore current
answer
flows parallel to shore within surf zone
question
barrier island
answer
depositional shore
question
true statements about groins?
answer
Groins can be constructed out of large blocky rocky material (rip-rap) or of sturdy wood pilings & Groins can be singular or many.
question
barrier flats
answer
found between dunes and high marsh
question
rip current
answer
moves water from swash zone out to sea
question
true statements about beach replenishments
answer
Beach replenishment is also known as beach nourishment. Beach nourishment involves dumping sand on the beach to replace lost sand. Beach replenishment is expensive because of the huge volume of sand that is necessary to replenish a beach.
question
Submerging shorelines do not have
answer
marine terraces
question
Eustatic changes in sea level refer to worldwide changes in the volume of seawater or in the volume of the ocean basins.
answer
True
question
The coastal area by surf is referred to as
answer
the beach
question
You own a beachfront lot that has been experiencing erosion due to beach starvation. Your neighbor to the north (up-current) has the same problem, so he gets permission to build a groin just north of your property line. Your response would probably be to __________.
answer
get permission to build a groin of your own near the southern boundary of your property