Exam 3 Flashcards
The energy for waves comes from
the winds
Most beaches have the largest waves in the
winter
The horizontal distance from one wave crest to the next crest is the
wavelength
Wave base for a wave is equal to
half the wavelegth
The energy of waves is concentrated on points and headlands by the process of
refraction
The circular motions of the water beneath a wave are called
orbitals
Seawalls can cause increased erosion by causing waves to
reflect
A pair of structures projecting out from the coast and intended to keep a harbor mouth open are
jetties
Beach erosion is greater problem today than in the past mainly because of
Most rivers are damned, cutting off the supply of new sand
The greatest loss of sand from beachse occurs as
the sand flows down submarine canyons
If a groin is built then there will be
some deposition on the side that the longshore current is coming from but an equal amount of erosion on the down-current side
Between the berm and the seasliffs you would find what part of the beach
Backshore
Between the foreshore and the backshore of a beach you will find
the berm
Larger waves will cause more sand to be stored in which part of a beach
Offshore
Sand is transported along th ebeach by
littoral drift
in the winter beaches are
Steeper
Wave erosion can produce
sea arches
A sand bar that runs parallel to the coastline may form what type of island
barrier
A sand bar attached to the coast on one end is called
spit
A tied island is connected to the coast by a sandbar called
tombolo
A series of marine terraces indicates
the coasline is uplifted
The steepest part of a continental margin is the
continental slope
At the bottom of a continental slope, you would expect to find
Continental shelf
Submarine telephone cables are most commonly broken by
turbidity currents
An ophiolite is thought to be
a slice of ocean crust
Which is not part of an ophilite sequence
rhyolite
the deepest part of the oceans are the
trenches
Submarine canyons are carved out by
turbidity currents
A rift valley is found in what part of an ocean
mid ocean-ridges
Sediment that settles through the water column is called
pelagic
The features that cross the ridges at right angles are
fracture zone
The movements of the turbidity currents following the 1929 quake are known because of
broken telephone cables
The shelf break is the boundry between the continental shelf and the
Continental slope
A structure that has dips away form it on all sides is a
dome
A fold with both limbs dipping towards the axis is a
syncline
A good example of a “sag pond” is
Lake Elsinore
A break in rocks where there has not been relative motion is called a
joint
If a syncline on a geologic mapforms a nose pointing towards the north is a plunging to the
south
The side of a fault surface is called the
foot wall
A thrust fault is a type of
reverse fault
The faults that result from compressional stress are
reverse
Normals faults would be most important at what type of plate boundary
diverging
Which of the following mountains formed as “pressure ridges” at a bend in the San andreas fault
San Gabriel
The “big bend” in the Sand Andreas fault is near the intersection of the San Adreas and
Garlock Fault
The epicenter of an earthquake, by definition, must always be at the
Surface of the earth
The largest earthquake likely to occur in Southern California is expected to be on the
San Andreas Fault
The odds of getting aftershocks after a large quake are
100%
The Richter scale measures
energy released in an earthquake
If the P and S waves arrive at almost the same time it means that
the epicenter is nearby
The seismic waves produced by a magnitude 8 quake will be how many times larger than the ones produced by a magnitude 5 earthquake?
1000
A magnitude 8 earthquake will release how many times the energy of a mag 5 quake
27,000
An earthquake that caused toatl destruction in an area would have a Mercalli intensity of
XII
Having water between the grains of sediment increases the chances of liquefaction
liquefaction
A seismic gap is
A segment of an active fault where an eathquake has not occurred in a long time
The typical height of a tsunami in the open ocean is
2-3 feet
Tsunamis travel at a speed of about
500mph
Large seawalls have been built to protect towns from tsunami in
Japan
Tsunamis
can be a serious threat to coastal areas after an earthquake
The area of the USA that is most at risk for a subduction zone earthquake and tsunamis is
Washington and Oregon
