Chapter 15

ocean currents

masses of water that flow from one place to another

surface currents

develop from friction btw. ocean and wind that blows across surface

Coriolis effect

The effect of Earth's rotation on the direction of winds and currents.

Gyres

Huge circular moving current systems dominate the surfaces of the oceans.

Where is each gyre located

Thermohaline circulation

ocean currents that occur due to differences in density due to temperature and salinity

Shore

area between lowest tidal level and highest areas affected by storm waves

Shoreline

contact between land and sea

coastline

seaward edge of the coast

beach

accumulation of sediment along landward margin of ocean

crest

top of the wave

trough

bottom of the wave

wave height

vertical distance btw trough and crest

amplitude

amplitude vertical distance from midpoint to crest or midpoint to trough

Wavelength

Horizontal distance between midpoint to crest or midpoint to trough

wave period

time it takes for one full wave to occur

wave base

negligible water movement below 1/2 wavelength

Fetch

distance wind travels

Beach drift

sediment moves in a zigzag pattern along beach face due to waves and gravity

Longshore currents

current in surf zone that flows parallel to shore

wave refraction

bending of waves

headland

land that sticks out into the sea

wave cut platform

flat area along a shore cut by wave erosion

marine terraces

when platform is no longer under water

sea stack

when sea arch has eroded away leaving rock detached from the rock shore

sea arch

rocks make an arch created as headland is eroded more from the sides

spit

ride of sand extending from land into mouth of an adjacent bay with an end that often hooks landward

baymouth bar

sand bar that completely crosses a bay. can have a river exiting through it

tombolo

a ridge of sand that connects an island to the mainland

Barrier islands

ridge of sand parallel to the shore but offshore

seawall

armors coast against force of breaking waves

breakwater

barriers built offshore parallel to coast to protect boats from breaking waves

Groins

barriers built at a right angle to the beach that are designed to trap sand

beach nourishment

by adding sand to the beach system

Where are the five gyres located

North pacific gyre, south pacific gyre, north atlantic gyre, south atlantic gyre, indian ocean gyre

How does ocean water circulate at the surface?

Formation by wind, Gyres, Coriolis Effect, Temperature, Warm currents, Cold currents

how does ocean water circulate at depth (vertical currents)

Density differences known as thermohaline circulation

How do ocean currents affect global and local temperatures

Heat transfer, Coastal Climate Modification (Waters take longer to heat up and cool off causing regulation)

How are waves generated?

Wind

What affects the size of a wave?

long fetch = bigger waves

What are the shoreline features that are produced from erosion?

Headland, wave-cut cliff, wave-cut platform, marine terraces, sea arch, sea stack

How does sediment move relative to the shoreline?

longshore current causes the sand too be dragged down the coast, gravity pulls the sand away = Beach drift makes a zigzag motion.

What are the depositional features of the shoreline

Baymouth bar, tombolo, barrier islands, spit

What methods can be used to stabilize shorelines and reduce erosion?

Jetties, groins, breakwaters, seawalls, beach nourishment