Ocean Environments Test Flashcards
Coast
the zone where the land meets the sea
Drowned coast
“Submergent coast”
2 types: ria, fjords
Ria coast
sea-level rise has drowned a region of coastal river valleys forming a series of wide estuaries often separated by a long peninsula
*Prevalent in Northwestern Europe, eastern US, and Australia
Fjord coast
sea-level rise has drowned one or more deep glacier-carved valleys
*Prevalent in coastal Norway, Chile, Canada, and New Zealand
Estuary
salt water meets fresh water
Emergent coast
occur where land has uplifted faster than the sea has risen since the last ice age.
Areas that were formerly sea floor may become exposed above the shoreline while former beaches often end up well behind the shoreline or even on clifftops.
Staircase structures called marine terraces are created by a combination of uplift and waves gradually cutting flat platforms at the base of cliffs.
Global sea-level change
Most important cause: the increase or decrease in the extent of the world’s ice sheets and glaciers
Related to Earth’s climate
If it cools, more water is frozen into glaciers=less oceans
If it warms up, more water melts from glaciers=more ocean volume
Affects ocean water temperature
Local sea-level change
Occurs when a particular area of land rises or falls relative to the general sea level
One cause occurs in regions where oceanic crust is being forced beneath continental crust.
Another cause is the glacial rebound-gradual rise of a specific area of land after an ice sheet that once weighed it down rises.
Coastal landscapes
can be classified into primary or secondary.
Primary coasts
have formed as a result of land-based processes like land erosion and volcanic activity.
Secondary coasts
have been shaped by marine erosional processes or by activities of organisms like corals and mangroves and people.
Wave-erosion coasts
secondary coast
waves hurl beach material against the cliffs which abrade the rock
each wave compresses air within cracks in the rock and on reexpansion, the air shatters the rock.
Marine-deposition coasts
Formed by sediment brought to the coast by rivers, eroded from headlands, or moved from offshore by waves.
Spit formation
sand and water are carried past the headland by longshore drift but the sand settles at the mouth of an estuary where the waves are opposed by the sluggish outflow from a river.
Beaches
deposits of sedimentary material
Commonly occur on coasts above the low-tide line
Sources of beach material-sediment brought to the coast by rivers or eroded from cliffs or the sea floor or the biological material such as shells.
Wind can also influence beach development and is instrumental in forming coastal dunes
Foreshore
the area between the average high and low tide lines
The seaward side of the foreshore is the nearshore while behind is the backshore
Backshore is submerged only during the very highest tides and includes a flat-topped accumulation of beach material called a berm.
beach face
The sloping area Seward of the berm making up most of the foreshore
beach cusps
a series of crescent-shaped troughs
swash zone
the part of the beach face that is covered and uncovered with water as the waves arrive
surf zone
Seaward of the swash zone extending out to where the waves break
what affects the type of beach that will form?
Level of wave energy, the direction the waves arrive from, and the geological makeup of a coast
Dissipative beaches
Gentle sloping, absorb wave energy over a broad area, made up of fine sand
Reflective beaches
Steep, shorter, and consists of coarser sediment
Pocket beaches
Isolated between two headlands
Headland
formed when the sea attacks a section of the coast; Looks like eroded rock
Drift-aligned beaches
waves arrive at an angle and sediment is moved along the beach by longshore drift
Beach Composition
Most beaches are composed of sand, gravel or pebbles produced from rock erosion
Sand grains of quartz and other minerals such as feldspar
Other materials: fragmented and skeletal remains of marine organisms
Higher wave energies=coarser materials
Coastal Dunes
:
Formed by the wind blowing sand off the dry parts of a beach
Develop in the area behind the backshore which together with the upper beach face supplies the sand
For dunes to develop, the sand has to be continually replaced
saltation
The actual movement of sand to form a dune occurs through a jumping and bouncing movement along the ground
foredunes
The dunes closest to the shore. Behind them is a primary dune ridge, secondary dune ridge, etc.
Marram Grass
common colonizer of embryo dunes (dunes in the beginning stages).
Develops deep roots that allow it to tap into groundwater.
Roots bind the sand together while the grass traps more blown sand assisting in foredune development.
Estuary
connects to an open sea, is narrow, and receives freshwater from 1 or more rivers.
Coastal lagoons
linked to the sea by one or more narrow channels through water flows in and out. Sometimes the channels open only at high tide.
Estuary formation 4 ways
First- the sea level may rise and flood an existing river valley on a coastal plain.
second- the sea level can rise to flood a glacier-carved valley forming a fjord
Third- the coastal wave action can also create an estuary
Fourth- the estuaries result from movement at tectonic faults in Earth’s crust.
Estuary environments
long and funnel-shaped, tides rush in
Fluctuations in salinity, reduction in photosynthesis, high concentrations of nutrients
