Shorelines Flashcards
What is the most important cause of
ocean waves?
If some ocean waves have a wavelength
of 30 feet, at what ocean depth will these
waves start to “feel” (disturb sediment on)
the bottom?
Explain why and how waves “break”?
When the speed of the water at the top advances beyond the speed of the water at the bottom.
How are longshore currents caused by
wave refraction? (And just what is “wave
refraction”, anyway?)
In which general direction do longshore
currents flow along the Alabama coast in
particular, and the northern Gulf of
Mexico in general?
On he northern Gulf of Mexico the water current flows from East to West.
What are “rip” currents? Why do they
pose a hazard to swimmers? What should
you do if you get caught in a rip current?
Name the two forces that cause changes
in sea level throughout a 24 hour day.
(Review the animation in the lecture
notes.)
Moons gravity and Earth’s centrifugal motion
Sketch a circle that represents the earth,
covered with ocean, and a circle that
represents the moon in orbit about the
earth. Where on the earth will high and
low tides occur, relative to the position of
the moon?
How is “seaward retreat” along coastlines
similar to “headward erosion” along river
valleys?
Before sea stacks were sea stacks, what
were they?
How does the shape of the shoreline
change during headland erosion?
It becomes more and more flat.
Why do sea side communities erect
groins, jetties, and/or breakwaters?
How can you tell the direction of the
longshore drift from the width of the
beach between groins?
What is the name of Alabama’s largest
(and longest) barrier island?
What were some of the effects of
Hurricane Katrina on Alabama’s barrier
island system? Hint: houses, beach width,
location of sand, etc.
