Lesson 13 Flashcards
What constantly modifies the shoreline?
waves
What is the coastal zone experiencing today?
intense human activity
What is common boundary?
shoreline
What is a dynamic interface between air, land, and the ocean?
shoreline
What provide most of the energy that shapes and modifies shorelines?
Wind-generated waves
Where do waves derive their energy and motion from?
wind
What does the height, length, and period of a wave depend on?
Wind speed
Length of time wind has blown
Fetch
What is the distance between a trough and a crest?
Wave height
What is the time interval between the passage of two successive crests?
Wave period
What is used to measure a wave?
wave height
wavelength
wave period
What is the distance that the wind has traveled across open water?
Fetch
What is the horizontal distance between crests?
Wavelength
What is the top of the wave called?
crest
What is the low area between waves?
low area between waves
What are the types of waves?
Wave of oscillation
Wave of translation
What wave has energy that moves forward, but not the water itself?
Wave of oscillation
Where does waves of oscillation occur?
in open sea in deep water
What happens when the translation wave begins to form?
the wave begins to “feel bottom”
Where does a translation wave form?
shallow water
depth of 1/2 the wavelength
What happens to a translation wave as the speed and length diminish?
the wave grows higher
What collapses in a translation wave before it breaks along the shore?
steep wave front
What advances up the shore in a translation wave and forms a surf?
turbulent water
What is erosion from the great force of breaking waves caused by?
wave impact and pressure
abrasion by rock fragments
Where does wave refraction cause wave energy to concentrate?
against the sides and ends of headlands
Where does wave energy end up caused by wave refraction and what happens to the wave attack?
spread out in bays
weakened
What is wave retraction?
Bending of a wave
What causes waves to arrive nearly parallel to the shore?
wave refraction
What is the consequence of wave refraction overtime?
erosion straightens an irregular shoreline
What is waves that each the shoreline at an angle cause the sediment to move along a beach in a zigzag pattern?
beach drift
What waves also produce longshore currents?
Oblique waves
What does wave refraction do to sand?
moves it along the beach
What are longshore currents?
Currents in the surf zone
How do longshore currents flow?
parallel to the coast
What do longshore currents easily move and roll?
fine suspended sand
larger sand and gravel
What factors caused shoreline features to vary?
_____along the shore
______
Wave _______
Whether the coast is _____, _______, or _____
rocks
currents
intensity
stable, sinking, or rising
What are features caused by wave erosion?
Wave-cut cliffs
Wave-cut platform
What are features associated with headlands?
Sea arch
Sea stack
Features related to beach drift and longshore currents
______
________ of sand extending from the land into the mouth of an adjacent bay
Often the end of a spit ______in response to wave-generated currents
spits
Elongated ridges
hooks landward
What are features related to beach drift and longshore currents?
Baymouth bar
Tombolo
Barrier islands
What is a sand bar that completely crosses a bay?
Baymouth bar
What is a ridge of sand that connects an island to the mainland or another island?
Tombolo
What is the result of shoreline erosion and deposition if the shoreline remains stable?
produce a straighter coast
Where are barrier island mostly found?
Atlantic and Gulf Coasts
What are low ridges of sand that parallel the coast 3 to 30 kilometers offshore?
barrier islands
How do barrier islands probably form?
in many ways
Shoreline erosion is influenced by several local factors including:
______ to sediment-laden rivers
_______ of tectonic activity
________ and composition of the land
Prevailing _____ and _____patterns
Configuration of the ______ and nearshore areas
Proximity Degree Topography wind and weather coastline
What are the three basic responses to erosion problems?
Building structures
Beach nourishment
Abandonment and relocation of buildings away from the beach
What are building structures that can be built?
Jetties
Groins
Breakwater
Seawall
Are building structures often an effective means of protection?
no
What building structure is
» Usually built in pairs to develop and maintain harbors
» Extend into the ocean at the entrances to rivers and harbors
Jetties
What building structure is
» Built to maintain or widen beaches
» Constructed at a right angle to the beach to trap sand
Groins
What building structure is
» Barrier built offshore and parallel to the coast
» Protects boats from the force of large breaking waves
Breakwater
What building structure is
» Barrier parallel to shore and close to the beach to protect property
» Stops waves form reaching the beach areas behind the wall
Seawall
What is the addition of large quantities of sand to the beach system?
Beach nourishment
Beach nourishment is only an economically viable ______ solution if a few areas
long-range
Shoreline erosion problems are ______ along the opposite coasts.
different
Which coast has broad, gently sloping coastal plains?
Atlantic and Gulf coast
Which coast has tectonically quiet regions?
Atlantic and Gulf coast
Which coast has relatively narrow beaches backed by steep cliffs and mountain ranges?
Pacific Coast
What is a major problem at the Pacific coast?
narrowing of many beaches
What are barrier islands also called?
barrier beaches
coastal barriers
Which coast as development that occurs mainly on the barrier islands that face the open ocean?
Atlantic and Gulf coast
Which coast has shoreline erosion that varies considerably from one year to the next largely because of the sporadic occurrence of storms?
Pacific coast
What coast receives the full force of storms?
Atlantic and Gulf coast
What develops because of uplift of an area or a drop in sea level?
Emergent coasts
What are features of an emergent coast?
Wave-cut cliffs
Wave-cut platforms
What is caused by subsidence of land adjacent to the sea or a rise in sea level?
Submergent coast
What are features of a submergent coast?
Highly irregular shoreline
Estuaries
What are Estuaries?
They drown river mouths
What are daily changes in the elevation of the ocean surface?
tides
What causes tidal bulges?
gravitational forces of the Moon, and to a lesser extent the Sun
What type of tide has a large daily tidal range?
spring tides
What type of tide has the least daily tidal range?
neap tides
What tide occurs during new and full moons?
spring tides
What tides occur during the first and third quarters of the moon?
neap tides
What tide occurs when gravitational forces of the Moon and Sun are added together?
spring tides
What tide occurs when gravitational forces of the Moon and Sun are offset?
neap tides
What tide is especially high and low tides?
spring tides
What are other factors that influence tides?
Shape of the coastline
Configuration of the ocean basin
What is the horizontal flow of water accompanying the rise and fall of the tide?
tidal currents
What re the types of tidal currents?
Flood current
Ebb current
What current advances into the coastal zone as the tide rises?
Flood current
What current has seaward-moving water as the tide falls?
Ebb current
What are areas affected by the tidal currents called?
What do tidal currents occasionally form?
tidal flats
tidal deltas
