Intro to Coastal

Erosional Coasts

Coasts that are not near a sediment source and receive high energy from environmental processes.

Tend to be narrow coastal zones.

Depositional Coasts

Coasts that gather sediment.

Deltas, barrier islands, reef coasts, and glaciated coasts

Core

3500km

made of iron and nickel

Inner Core

0-1200km

made of iron and nickel

solid

Outer Core

1200 - 3500km from earth’s center

Molten

Mantle

3500-6400km

made of magnesium silicate

80% of earth’s volume (60% of mass)

Asthenosphere

Upper part of mantle extending 350km down

semi-plastic (1-2% liquid)

Mesosphere

Lower mantle

solid and non-plastic (greater pressure)

Crust

Outer 5-70lm of earth

made of cation alumino-silicate

Lithosphere

Composed of oceanic and continental crust and underlying uppoermost portion of the mantle

100km and behaves as a solid, rigid slab

broken up into 8 major plates

Divergent Boundaries

Plate boundaries of the spreading oceanic ridges

for new oceanic crust from asthenosphere

Continent-Continent Convergent Boundaries

Plate boundaries pushing together, mountain building like Himalayas

Convergent Boundaries

Plate boundaries pushing together, sub ducting of denser oceanic crust underneath lighter continental material

Transform Boundaries

plates moving past each other

ridge crests and on some continents

Continental Shelves

submerged shallow extensions of the continent stretching from the shore to the shelf/slope break

Continental Slopes

Extend from continental shelf to the continental rise (unless there is a trench)

Continental Rises

Extend from the continental slope to the abyssal plain

Atlantic Margin

Passive margin, no volcanic or seismic activity, wider continental shelves than active margins.

Passive Margin

The edge of a continent that coincides with the middle of a lithosphere plate

Pacific Margin

Active margin, edge of 2 lithospheric plates, tectonically active with subduction zones

Island Arc Collision Coasts

Tectonically active and earthquakes happen, but differ from continental collision coasts in that it is the conversion of two oceanic plates

Trailing Edge Coasts

Non-plate boundary, passive margin, tectonically stable

broad coastal plain and continental shelf, have accretionary landforms such as barrier islands

Neo

Type of trailing edge coast

Earliest stage, near spreading center so narrow oceanic sea, little sediment available

Afro Edge Coast

Type of trailing edge coast, both coasts of continent are trailing edge type, some extensive river basins and deltas

Amero

Type of trailing edge coast

oldest

well developed river basins and deltas, include depositional landforms such as barrier islands

Marginal Seas

Island arc and continent enclose a small ocean

near converging plate margin, not tectonically active, low relief on continents and well-developed basins

low wave energy, can accumulate large amounts of sediment

Barrier Coastline

Composed of unconsolidated sediment, impacted by wind, waves, and tides, common overwash.

Separated from the mainland by an enclosed/semi-enclosed body of water

Bay Barriers

One headland to another enclosing a body of water

Spits

Attached at one end to the mainland and growing on the other

Barrier Islands

Detached from the mainland by inlets

Microtidal Barrier Islands

Barrier Islands that are long and linear, wave climate dominated with only flood tidal deltas developed

Mesotidal Barrier Islands

Short barrier islands with greater width and developed flood and ebb tidal deltas developed

Beach

Region from the Mean Low Tide to the shore, vegetation, dune, or cliff

Backshore

from foreshore to landward end of the beach, not covered with water save for storms

Foreshore

MLT —> Intertidal Region —> through the beach face or swash zone (or beginning of the berm)

Blowover

Usually in dunes, onshore winds blow sand or top of dune creating angle of repose on the landward side of the dune

Washover Fans

Barrier island component deposited during intense storms when beach-dune system is over-stepped by waves and storm surges.

Flood Tidal Deltas

Shoreward tides of inlet, formed during flood tides

Ebb Tidal Deltas

Seaward of inlet, formed during ebb tide

Tide Dominated Delta

Ebb Tidal Delta, well developed sandbars on both sides of the inlet tending perpendicular to barrier islands

Mixed

Ebb Tidal Delta

Sand bar is arched across the inlet

Wave

Ebb Tidal Delta

very little sediment accumulation

Tidal Prism

Flux of water through an inlet. Controls size and stability of inlet.

Transgression

Landward migration, caused by washover fan deposition

Wave Dominated Barrier Island

Type of Barrier Island

longshore drift causes linear accumulation of sediment producing a long narrow barrier island

Tide Dominated Barrier Island

Type of Barrier Island

Short islands, stable inlets

Mixed Energy Barrier Island

Type of Barrier Island

refraction around ebb tide delta reverses longshore current creating one wide end of barrier isalnd and one narrow end

Marine Terrace

Wave cut bench that gets uplifted, above sea level

Delta

Outwash from a river or stream

Tomobolo

Connects island to island, or island to mainland, perpendicular to incoming waves

Groins

Short extensions of rock or other material placed at right angles to the beach.

Jetties

Structures intended to keep sand from flowing into a channel, intended to protect an inlet

Coastal Lagoon

Shallow water bodies separated from the ocean by a barrier, connected at least intermittently to the ocean by one or more restricted inlets, and oriented shore-parallel

Welded Baymouth Barrier

Connect headlands at outer edge of embayment, common in microtidal

Emergence Theory

Barrier islands form as waves break over a submerged bar, and the bar emerges above sea level due to deposited sediment

Spit Growth

Barrier islands form from spits by currents flowing parallel to the coast (longshore current). Individual islands were created when the spits were breached by wabes during storms, creating inlets

Dune Ridge Submergence

Barrier islands form by the drowning of the coastal area during a rise in sea level

Estuary

Semi-enclosed and coastal body of water, free connection with open sea, sea water is diluted with fresh water derived from land drainage.

Coastal Plain Estuaries

Estuaries formed at the end of the last ice age when rising seawater flooded (drowned) existing river valley

Fjords

Glaciated, U-shaped valleys with steep walls.

Glacial deposits pish ahead by advancing glaciers, creating a shallow sill near the ocean entrance

Bar Built Estuaries

Estuaries that are common barrier islands that are separated from land by a shallow lagoon.

Formed by the creation of sand bars parallel with the shore, usually adjacent to slow flowing rivers.

Tectonic Estuaries

Estuaries caused by earthquakes where folding or faulting may create bays with narrow inlets to the sea.

Deep Water Waves

Occur when water depth is greater than ½ the wavelength

Shallow Water Waves

Occur when water depth is less than ½ the wavelength

Wave Refraction

Angled crest lines are rotated as they approach the shore.

Wave rays, lines perpendicular to crest lines

Rip Currents

Caused by convergence of longshore currents and wave set up