Oceanography Terms

Protoearth

The evolution of the planet in close proximity to a supernova explosion.

Degassing - Theory to the source of water

Water given off as steam from lava and gases escaping from the Earth’s interior.

Cometary impact - theory to the source of water

Water derived from icy comet impacts in early Earth History

Subduction

The process of tectonic subduction occurs when two tectonic plates converge together. The more dense plate will generally subduct under the less dense plate

Continental margins - passive

not on plate boundaries, lack active volcanoes & earthquakes

Continental margins - active

on plate boundaries, have active volcanoes & earthquakes

Sediment type - lithogenous

Gravel, sand, silt, clay. formed by weathering, transportation and deposition.

Sediment type - biogenous

Shells, bone, teeth, droppings. come from hard parts in organisms that have died

Ooze

sediment with over 30% biogenic material

Sediment type - hydrogenous

Chemical precipitates - lime, salt, sulfides. forms from dissolved materials come out of solution (precipitate)

Island arcs

Arcuate chains of islands, , separated from continents by a marginal sea. Have explosive stratovolcanoes & earthquakes

Carbonate Compensation Depths

The depth at which carbonate particles sinking \n from above dissolve. Ranges from 3500 - 6000 meters

Shield volcanoes

Large but have gently sloping sides, erupt mostly basaltic lava

Sea mount

Active or inactive volcano that has never been \n built above sea level

Oceanic island

Sea mount that has grown above sea level. Either active or recently inactive

Guyot

Flat top submerged inactive volcanoes. Oceanic islands whose tops have been eroded by sea wave action

Coral atoll

Oceanic island or guyot kept at or above \n sea level by coral growth

Ridge

sharp crested tops, rift valley, form by slow spreading rates

Rise

smooth tops, little or no rift valley, form by fast spreading rates

Submarine hot springs

Biologically rich zones, powered by earth’s internal heat, energy from chemosynthesis

Chemosynthesis

Energy released by breakdown of chemical substances such as sulfur compounds

Xenoliths

rocks carried to the surface by magma

Gas bubble texture - vesicular

A rock filled with air pockets or holes

Gas bubble texture - scoria

hardened lava that has retained the vesicles from escaping \n gases

Amygdules

vesicles that have been filled in with new mineral material \n over time

Viscosity

the resistance to flow of a substance. the more silica there is, the more viscous the substance will be.

Ash

Dust sized particles produced from a volcanic explosion, less than 2 mm in size.

lapilli/cinders

Bead to walnut sized particles ejected from volcanic eruptions, 2 - 64 millimeters in size

bombs

Large chunks and fragments ejected during a volcanic eruption, Greater than 64 millimeters

Types of lava - Pahoehoe

Smooth, billowy; locally ropey or lower viscosity flows; not degassed

Types of lava - AA

Rough, spiney; higher viscosity - cooler flows; degassed

Types of lava - pillow lava

Forms from underwater eruptions

Shield volcano

a gentle sloping & very broad volcano, formed from basaltic lavas, large lava flows

Cinder cone

built from ejected lava fragments, aka scoria cones

composite cones

aka stratovolcanoes, made of very viscous granitic lava, pyroclastic in eruptive nature, little lava flow

pyroclastic flow

Hot flows of ash, rock, and gases rushing down the slopes of a \n volcano

lahar

Large mudflows created from ash mixing with water

fissure eruptions

long narrow cracks in the earth’s crust that erupt low viscosity basaltic lavas

neritic

near-shore

pelagic

deep ocean floor

Exclusive Economic Zone (EEZ)

says that coastal nations own all resources 200 nautical miles or to the edge of the continental shelf, whichever is furthest

placer deposits

Concentrations of dense minerals made by waves and river and ocean currents

gas hydrates

a frozen fizz of methane and water. Stable as a solid only at low \n temperatures and high pressures found at or near seafloor

Mariculture

farming of the sea

Aquiculture

farming of all water bodies

hydrogen bonding

link between dipolar molecules. Causes Water to Freeze and Condense at Higher Temperatures than Normal

Salinity

total amount of dissolved solids in water

residence time

Average length of time a given chemical stays in solution in sea water

Sigma T

move decimal three places to the right for given density

Photic zone

sufficient sunlight for photosynthesis, depth usually 20-60 meters

Aphotic zone

Insufficient light for photosynthesis, most of ocean

Thermocline

zone of rapidly changing temperature with depth

Halocline

zone of rapidly changing salinity with depth

Pycnocline

zone of rapidly changing density with depth

SOFAR channel

Zone of low sound velocity at approximately the thermocline. Sound waves ‘trapped’ here by wave refraction, can go long distances

Surface currents

driven by prevailing winds, forms gyres, affects waters down to 2000 meters

Coriolis effect

Apparent deflection of north and south moving material on a rotating planet. Currents deflect to the right in the north and deflect to the left in the south

gyre

Loop like currents of water driven by winds, continent placement, and Coriolis effect

thermohaline currents

responsible for the deep circulation of the ocean, dense waters sink and light waters rise (powered by density)

downwelling

Cold, salty, dense water sinks downward from the surface zone

upwelling

Deep water returns to surface because of contrasting density. Cold nutrition rich water creates blooms of high fertility

El Nino

Climate perturbation recurring every 2 - 8 years in late Fall, Winter, trade winds decline, warm water shifts east across the pacific

La Nina

trade winds increase, upwelling increases, less known effect on global climate

Fetch

the length of water over which the wind blows

deep water waves

circular motion, move faster, less steep, longer wavelength, lower wave height, do no erosion of shore or bottom, in water deeper than the wave base

shallow water waves

elliptical motion, move slower, more steep, shorter wavelength, higher wave height, becomes unstable and breaks, erodes coastline and bottom, in water shallower than the wave base

surging breakers

happen on beaches where the slope is very steep. The wave does not actually break. Instead, it rolls onto the steep beach. These kinds of breakers are known for their destructive nature.

plunging breakers

happen on beaches where the slope is moderately steep. This kind of wave normally curls over forming a tunnel until the wave breaks. Expert surfers love this type of wave!

spilling breakers

occur on beaches with gentle slopes. These waves break far from \n the shore, and the surf gently rolls over the front of the wave.

Resonance

Magnification of a vibration caused by constructive interference. Causes larger than normal tidal range, causes tidal bores moving up rivers

Ebb tide

the tide going out to sea

Flow tide

the tide coming onto land

Diurnal tide

1 High, 1 Low tide per day

Semidiurnal tide

2 High, 2 Low tides per day of about equal height and range

Mixed tide

2 High, 2 Low tides per day with different heights and ranges

Neap tide

Tide occurring twice monthly with a particularly low tidal range. coincides with the first and last quarter of the moon.

Spring tide

Tide occurring twice monthly with a particularly high tidal range. coincides with the new and full moon.

longshore current

Current formed when waves strike shore at an angle. Major factor in erosion and deposition along coasts

Nearshore current

when waves hit the shoreline almost totally perpendiculary.

berms

Nearly flat part of beach formed by wave \n transported material

primary coast

Landforms shaped primarily by non-marine processes

secondary coast

landforms shaped primarily by marine processes

Estuary

Semi-enclosed parts of the sea where fresh and salt water mix

Salt-wedge estuary

Large river input & small tidal input

Mixed estuary

Large tidal input & small river input

isotonic

Cannot regulate internal salinity and cannot adapt to major changes in salinity

hypotonic

Can regulate internal salinity and can adapt to major changes in salinity

Poikilothermic

Cannot regulate internal temperature, cold blooded

Homeothermic

Can regulate internal temperature \n • Warm blooded \n • Require insulation (fat, fur)

Bioluminescence

Organically produces light due to luciferin and luciferase enzymes

Pressure of the ocean

Increases with depth at a rate of 1 atmosphere per 10 meters (1 atm/10 m)

Turbidity

the cloudiness of water, Caused by very fine sized particles that will not settle out of water

fouling

the sticking together of many objects

Foraminifera

Amoebas with calcareous shells

Meroplankton

Eggs, spores, and larvae of nektonic or benthic organisms

Primary Productive

Amount of organic material formed by autotrophs in a given area in a given time

Caudal fin

tail fin, good indicator of lifestyle. lungers or cruisers

Sessile

anchored to one spot for life

motile

able to crawl/move around on the bottom

Tropical depression

wind speeds stay under 45 mph