marine & coastal processes (#5)

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coastal zone

this is the interface between land and water;

this is continually changing because of the dynamic interaction between the oceans and the land

tides, currents, and waves

3 factors that bring energy to the coast

coastal processes

 activities or events happening in the marine environment

• ex. waves, tides, sea level change, crustal movement, and storm surge

atmospheric pressure, temperature, movement of the Earth, moon

some environmental factors which drive coastal processes

tides

COASTAL PROCESSES:

refers to the gravitational pull between the Earth and the moon;

because the moon is closer to the Earth than the Sun, it has a larger effect and causes the Earth to bulge toward the moon

2 high tides and 2 low tides

usually, how many high tides and low tides each day?

ocean currents

COASTAL PROCESSES:

when the surface of the oceans move in response to winds blowing over the surface;

oceanic circulation is 3-dimensional

surface ocean currents

COASTAL PROCESSES:

these tend to flow in patterns similar to the winds as discussed previously, and are reinforced by the Coriolis Effect;

unlike winds, these are diverted when they encounter a continental land mass 

clockwise, counterclockwise

UNDER OCEAN CURRENTS:

Because of the Coriolis effect, ocean current circulation is ________ in the northern hemisphere and ________ in the southern hemisphere.

vertically

UNDER OCEAN CURRENTS:

Seawater also circulates ________ as a result of changes in density controlled by changing salinity and temperature.

ocean waves

COASTAL PROCESSES:

these are caused by the movement of the air masses in the coastal environment;

water travels in loops in these

coastal erosion / erosion by waves

COASTAL PROCESSES:

waves can only erode if the water along a coastline is shallower than 1/2 times the wavelength;

when the wave breaks as it approaches the shoreline, vigorous _____ is possible due to the sudden release of energy as the wave flings itself onto the shore

rigorous erosion

UNDER COASTAL EROSION:
______ erosion of sea floor takes place in the surf zone

transportation of sediment by waves & currents

COASTAL PROCESSES:
sediment that is created by the abrasive action of the waves or sediment brought to the shoreline by streams is then picked up by the waves and transported;

where beach material is transported in the sea and along the coast;

mainly done by longshore drift

finer grained sediments

UNDER TRANSPORTATION OF SEDIMENT:

these sediments are carried offshore to be deposited on the continental shelf or in offshore bars

coarser grained sediment

UNDER COASTAL TRANSPORTATION:

these can be transported by longshore currents and beach drift

coastlines

these represent a balance between wave energy and sediment supply

True

TRUE OR FALSE:

If wave energy and sediment supply are constant, then a steady state is reached. If any one of these factors change, then shoreline will adjust.

longshore drift

UNDER COASTAL TRANSPORTATION:

when waves move in the direction of the prevailing wind at an angle to the beach

still-water deposition

COASTAL PROCESSES:
the laying down of sediment carried by wind, flowing water, the sea or ice;

sediment can be transported as pebbles, sand and mud, or as salts dissolved in water.

rocky coasts

TYPES OF COASTS:

coastlines that have experienced recent tectonic uplift as a result of either active tectonic processes;

this may occur anywhere where wave action has not had time to lower the coastline to sea level

beaches

TYPES OF COASTS:

wave washed sediment along a coast;

these occur where sand is deposited along the shoreline

barrier islands

TYPES OF COASTS:

long narrow ridge of sand just offshore running parallel to the coast;

most of these were built during after the last glaciation as a result of sea level rise

• ex. some along the east and Gulf coasts of the US

beach drift and longshore drift

UNDER BARRIER ISLANDS:

barrier islands are constantly changing & grow parallel to the coast by _____ drift and ______ drift;

these are eroded by storm surges that often cut them into smaller islands.

lagoon

UNDER BARRIER ISLANDS:

narrow channel of water separating the island and coast

reefs

TYPES OF COASTS:
these consist of colonies of organisms like corals;

these only form in shallow tropical seas as the mentioned organisms can only live in warm waters & need sunlight to survive;

these protect the coastline from waves

fringing reefs

2 TYPES OF REEFS:

these form along coastlines close to the sea shore

barrier reefs

2 TYPES OF REEFS:

these form offshore, separated from the land by a lagoon

atoll

TYPES OF COASTS:

a circular island forms as reefs trap sediment;

this surrounds a body of water called a lagoon

atoll

TYPES OF COASTS:

these develop with underwater volcanoes, called seamounts;

first, the volcano erupts, piling up lava on the seafloor. as the volcano continues to erupt, the seamount's elevation grows higher, eventually breaking the surface of the water.

True

TRUE OR FALSE:

In the deeper oceans reefs can build up on the margins of volcanic islands, but only do so after the volcanoes have become extinct. After the volcanism ceases, the volcanic island begins to erode and also begins to subside. As the island subsides, the reefs continue to grow upward. Eventually, the original volcanic island subsides and is eroded below sea level.

• After this, an atoll forms.

estuaries

TYPES OF COASTS:

these are coastal river valleys flooded by sea water;

characterized by mixing of fresh & salt water

tidal flats

TYPES OF COASTS:

these are zones along the coast that are flooded during hight tides and form in the intertidal zones lacking strong waves;

they’re common behind barrier islands or in estuaries

sediment starvation

COASTAL HAZARDS:

when rivers do not bring enough sediment to be deposited on the beach

biological activities

COASTAL PROCESSES:

marine _____ includes energy-fixing microorganisms in transferring to and sustaining all of the other organisms in the marine system

diurnal tide

TIDES BASED ON FREQUENCY:

when any region experiences only 1 high tide & 1 low tide on a lunar day cycle

semi-diurnal tide

TIDES BASED ON FREQUENCY:

2 high tides & 2 low tides occur on a lunar day;

the height of peaks & the depth of troughs for both high & low tides are the same

mixed tide

TIDES BASED ON FREQUENCY:

2 high tides & 2 low tides occur;

height of both high tides & depth of both low tides are not the same

spring tides

TIDES BASED ON FREQUENCY:

sun and moon align & pull the ocean's surface in the same direction;

happens 2x in a lunar month during a full or new moon

neap tides

TIDES BASED ON FREQUENCY:

sun & moon are at a perfect angle to one another;

happens 7 days after spring tide & during the first and last quarters of the moon;

resulting oceanic bulge & gravitational attraction of the sun cancel each other out