Chapter 14
abyssal plains
-are the flat, deep part of
the ocean floor, two to three miles
below sea level.
asymmetric ripple mark
-is a ripple mark with a
steep, short slope on the downstream
side of its crest and a low
angle, long
slope on the upstream side.
Preserved ripple marks of this type are indicators
of
current directions of ancient streams.
-asymmetric ripple marks-closer view
atoll
-is a circular chain of coral islands surrounding a lagoon.
barrier island
-is a long island built of
sand that runs parallel to the shoreline.
-Cape Cod
beach
-is a relatively flat,
slightly dipping portion of the shoreline of a lake or ocean; may be covered
with
sand, gravel, or rocks.
continental shelf
-is the low sloping
submerged portion of the edge of a continent that ranges from the shoreline to a
depth of approximately 200 meters. Sediments deposited in this region are
usually laid down in a
stable, quiet manner.
continental slope
-is the steeper slope of
the submerged margin of a continent that extends from the continental shelf
to
the continental rise; this region can be an active area of turbidity flows.
crossbedding
-is a primary sedimentary
structure in which one set of inclined sedimentary layers is beveled off
by
an
erosion process and a new set of sedimentary layers is deposited on top of the
truncated
original
layers; common in stream sediments and sand dunes.
island arc
-is a curved chain of
volcanic islands adjacent to an oceanic trench and overlying a subduction
zone.
longshore drift
-is a current moving parallel to the shoreline that is responsible for moving sand grains along the shoreline.
oceanic ridge
-is an underwater ridge
formed where two crustal plates are pulling apart. The Mid-Atlantic Ridge
and
the
East Pacific Rise are two good examples.
seafloor spreading
-occurs along the crest of
oceanic ridges where the oceanic crust is being pulled apart and lava is
filling
the fissures, thereby creating new seafloor.
seismic sea wave
-is the correct term to use
in referring to large ocean waves created by earthquakes.
Earlier terms applied
to these waves were tidal waves and tsunamis.
-spit
-is a linear extension of land into an ocean or lake; may consist of a sandbank, shoal, or reef.
spreading center volcanism
-occurs along an oceanic
ridge where seafloor spreading is occurring, lava emerges where the
oceanic
plates
are pulling apart and opening up fissures.
symmetric ripple marks
-are symmetric on both sides of the ripple mark.
Symmetric ripple marks are also known as
oscillation ripple
marks because they
are formed by the back and forth motion of waves.
-ripple marks on a California beach
trench
-is a depression on the ocean floor where oceanic crust is being subducted.
tsunami
-is the Japanese word for seismic sea wave. It actually means harbor wave.
turbidites
-are sediments deposited by turbidity flows.
-turbidites-Anchor Bay, California-1
-turbidites-Anchor Bay, California-2
-turbidites-Anchor Bay, California-3
-turbidites with a normal fault
turbidity flow
-is an underwater flow of
dense turbid water; sometimes this density current is caused by an
underwater
avalanche on the continental rise which was triggered by an earthquake.
wave action
-is a mechanical weathering
force capable of breaking and rounding rock fragments through
constant abrasion.
-wave action along California coast
-wave action in Laguna Beach, California