Chapter 14
               Oceans, Waves,and Beaches

                Physical Geology Illustrated Vocabulary
Cochise College                                                     
Geology Home Page  
Roger Weller, geology instructor
wellerr@cochise.edu   


Malibu, California coastline


Chapter 14
copyright 2015 R.Weller
last edited 12/7/15
  
 

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             

-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.

-sandy beach            

-rocky beach  

           

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.

-crossbedding          

-crossbedding-close up           

           

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 cut by a fault             

-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           

-humans enjoying wave action 

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