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92: Glossary

  • Page ID
    4541
  • Antarctic Bottom Water

    water at abyssal depths in the ocean that forms from the sinking of dense cold water adjacent to Antarctica (9.8)

    Beaufort scale

    a 0-12 scale describing the wind conditions at sea, often reflected in wave heights (10.2)

    Boyle’s Law

    the volume of a gas is inversely proportional to the pressure (6.1)

    Carboniferous

    a geologic period that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya

    Coriolis Effect

    the tendency for the path of moving bodies (e.g., ocean currents) to be deflected on the surface of the Earth, to the right in the Northern Hemisphere and to the left in the Southern Hemisphere (8.2)

    Cretaceous

    a geologic period that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya

    Ekman spiral

    where each layer of water is deflected relative to the layer above it, forming a spiral that extends down to about 100 m (9.3)

    Ekman transport

    bulk transport of water due to the Ekman spiral; the net movement Ekman transport is 90 degrees relative to the wind direction (9.3)

    El Niño

    a periodic climatic situation in which warm water extends all or most of the way to the eastern edge of the equatorial Pacific (9.6)

    El Niño-Southern Oscillation (ENSO)

    the fluctuating atmospheric conditions that lead to the localized ocean warming of El Niño (9.6)

    Eocene

    a geological epoch lasting from 56 to 33.9 million years ago

    Ferrel Cell

    the atmospheric convection cells between 30 and 60 degrees latitude (8.2)

    Ga

    (gigaannus) billions of years before the present

    Gulf Stream

    the major surface current flowing northwards along the Atlantic coast of the U.S. and Canada  (9.2)

    Hadley Cell

    the atmospheric convection cells between the equator and 30 degrees latitude (8.2)

    Henry’s Law

    as the pressure increases, a fluid will contain more dissolved gas (6.1)

    Intergovernmental Panel on Climate Change (IPCC)

    an international body established in 1988 by the UN’s World Meteorological Organization and the UN Environment Program to prepare periodic reports on the status of global climate change and its mitigation (8.5)

    Intertropical Convergence Zone

    the area near the equator where the northeast and southeast trade winds converge; known for weak winds, it is also called the doldrums (8.2)

    Jovian planet

    a gas giant (3.1)

    La Niña

    a periodic climatic situation in which colder than normal water extends throughout the equatorial Pacific (9.6)

    Langmuir circulation

    corkscrew circulation patterns formed parallel to strong winds; they only extend a few meters below the surface (9.7)

    Laurentide Ice Sheet

    the continental glacier that extended across central eastern North America during the Pleistocene, covering most of Canada and a significant part of the United States (3.2)

    Ma

    (Megaannus) millions of years before the present

    Mercator projection

    a map projection where latitude and longitude are both represented as straight, parallel lines intersecting at right angles (2.3)

    Mesozoic

    the geological era from about 252 to 66 million years ago

    Milankovitch cycles

    millennial-scale variations in the orbital and rotational parameters of the Earth that have subtle effects on the Earth’s climate (8.5)

    Mohorovičić discontinuity (Moho)

    the boundary between the crust and the mantle (3.3)

    North Atlantic Deep Water

    deep Atlantic Ocean water that has descended in the far north of the basin in the area between Scandinavia and Greenland (9.8)

    Paleocene

    a geological epoch that lasted from about 66 to 56 million years ago

    Paleozoic

    the geologic era lasting from 541 to 252 million years ago

    Pangaea

    the supercontinent that existed between approximately 300 and 180 Ma; it contained all of the  modern continents combined into a single land mass (4.1)

    Permian

    a geologic period which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya

    Phanerozoic

    the eon on the geological time scale covering time from the beginning of the Cambrian period 541 million years ago to the present, and comprising the Paleozoic, Mesozoic, and Cenozoic eras

    Polar Cell

    the atmospheric convection cells between 60 degrees latitude and the pole (8.2)

    SOFAR channel

    range of depths around 1000 m where sound travels the slowest, so sound waves are refracted back into the channel and can be propagated long distances (6.4)

    abyssal plain

    the flat seafloor of the deep ocean, typically beyond the limits of the continental slopes (1.2)

    abyssal zone

    the region of the seafloor between 4000-6000 m (1.3)

    abyssopelagic zone

    the deeper parts of the open ocean, between 4000 and 6000 m; also known as the abyssalpelagic zone (1.3)

    accretion (planetary)

    the process by which solid celestial bodies are added to existing bodies during collisions (3.1)

    active continental margin

    where the boundary between the continent and the ocean is also a tectonic plate boundary (1.2)

    aeolian

    processes related to transportation and deposition of sediments by wind (12.2)

    albedo

    the reflectivity of a surface of a planet (expressed as the percentage of light that reflects from the surface) (8.1)

    amphidromic circulation

    gyre-sized tidal patterns where a tidal crest rotates around an ocean basin (11.2)

    amphidromic point

    the center point around which amphidromic circulation rotates; there is near-zero tidal range at the amphidromic point (also called a tidal node or amphidromic node) (11.2)

    anoxia

    conditions of zero or extremely low dissolved oxygen, usually below 0.5 mg/L (5.4)

    anthropogenic

    resulting from the influence of humans (8.5)

    aphotic zone

    depths beyond 1000 m where there is no light penetration (1.3)

    arch

    a rock weathering remnant in the form of an arch (typically along a coast and resulting from wave erosion) (13.3)

    asthenosphere

    the part of the mantle, from about 100 to 200 km below surface, within which the mantle material is close to its melting point, and therefore relatively weak (3.2)

    atmospheric wave

    a wave formed in the atmosphere at the boundary between air masses of different densities (10.1)

    atoll

    a ring-shaped carbonate (or coral) reef or series of islands (4.10)

    backshore

    the region of the beach above the high tide line, which is only submerged under unusually high wave conditions (13.1)

    backwash

    the wash of wave water down the slope of a beach (13.1)

    bar-built estuary

    an estuary created when a sand bar or barrier island cuts off the estuary from mixing completely with seawater  (13.6)

    barrier island

    a long, thin island parallel to the shore, created through the deposition of sand (13.4)

    barrier reef

    a reef that forms a barrier to waves along a coast; it is separated from land by a lagoon  (4.10)

    barycenter

    the center of mass in the Earth-moon system around which they rotate (11.1)

    basalt

    a volcanic rock that makes up much of the oceanic crust (3.2)

    bathyal zone

    the region of the seafloor from the shelf break to 4000 m  (1.3)

    bathymetry

    pertains to measuring the depths of the ocean (1.4)

    bathypelagic zone

    the moderately deep parts of the open ocean, between 1000 and 4000 m (1.3)

    baymouth bar

    a spit that extends across the mouth of a bay (13.4)

    beach face

    the area of a beach between the high and low tide lines (13.1)

    benthic

    refers to the environment of the seafloor (1.3)

    benthos

    refers to the community of organisms living on or in the ocean floor (1.3)

    berm

    a flat area of a beach in the backshore area (above the high tide level) (13.1)

    big-bang theory

    the theory that the universe started with a giant expansion approximately 13.77 billion years ago (3.1)

    biogenous sediment

    sediment created from the remains of organisms (12.3)

    blocky iceberg

    iceberg with a flat top and steep sides, but their length to height ratio is not as great as it is for a tabular iceberg (14.2)

    blowhole

    a hole in the ceiling of an arch or sea cave through which water is ejected when waves approach (13.3)

    body wave

    a seismic wave that travels through rock (e.g., a P-wave or an S-wave) (3.3)

    boulder

    a sediment with a grain diameter of at least 256 mm (12.1)

    boundary currents

    ocean currents whose properties are influenced by the presence of a coastline (9.1)

    brackish

    seawater of low salinity; part fresh water, part seawater (13.6)

    breaker

    an unstable wave that has collapsed (10.3)

    breakwater

    a structure built offshore in order to deflect the energy of waves (13.5)

    buffer

    a solution that moderates changes in pH when acids or alkalis are added to it (5.5)

    calcareous sediment

    sediments composed of calcium carbonate, often from the shells of marine organisms (12.3)

    calving

    when ice breaks off of the front of a glacier and collapses into the water (14.2)

    capillary waves

    small ripples that form on the water surface under light winds; their restoring force is surface tension (10.2)

    carbonate compensation depth

    the depth in the ocean (typically around 4000 m) below which carbonate minerals are soluble (12.6)

    celerity

    the speed of a wave (10.1)

    chemosynthesis

    the creation of organic compounds using the energy from inorganic chemical reactions (4.11)

    chip log

    a device for determining a ship’s speed at sea, by measuring the rate at which a line is unspooled when cast overboard (2.2)

    clay

    sediment particle that is less than 1/256 mm in diameter (12.1)

    climate feedback

    a process by which the physical effects of a climate forcing can have other effects (either negative or positive) on the climate (8.5)

    climate forcing

    a mechanism, such as a change in greenhouse gas levels, that forces the climate to change (8.5)

    coastal plain estuary

    an estuary formed when sea level rises and submerges a river valley (also known as a drowned river valley estuary) (13.6)

    coastal straightening

    the tendency for an irregular coast to be straightened over time by coastal erosion processes (13.3)

    cobble

    sediment particle that is between 64 and 256 mm in diameter (12.1)

    coccolithophore

    photosynthetic algae that makes its test (shell) out of calcium carbonate (7.2)

    compensation depth

    the depth where the rate of photosynthesis equals the rate of respiration (7.3)

    conduction

    the transfer of heat through direct contact (8.1)

    conservative ions

    ions whose proportions are the same regardless of overall salinity; the major ions in seawater (5.3)

    constructive interference

    where the interaction of multiple waves creates waves larger than any of the component waves (10.2)

    continental crust

    the Earth’s crust underlying the continents (as opposed to ocean crust) (3.2)

    continental drift

    the idea that the continents have moved over the surface of the Earth over geological time (4.1)

    continental margin

    the region of transition from the land to the deep sea floor, i.e. between continental and oceanic crust (1.2)

    continental rise

    the area at the bottom of the continental slope, where it transitions to the abyssal sea floor (1.2)

    continental shelf

    the shallow (typically less than 200 m) and flat sub-marine extension of a continent (1.2)

    continental slope

    the steeper part of a continental margin, that slopes down from a continental shelf towards the abyssal plain (1.2)

    convection cell

    a rotating region in a fluid in which upward motion of warmer, low density fluid in the center is balanced by downward motion of cooler, denser fluid at the periphery (4.3)

    convergent boundary

    a plate boundary at which the two plates are moving towards each other (4.6)

    core

    the metallic interior part of the Earth, extending from a depth of 2900 km to the center (3.2)

    core-mantle boundary

    the boundary, at 2900 km depth, between the mantle and the core (3.2)

    cosmogenous sediment

    sediment derived from extraterrestrial sources (12.5)

    crest

    the highest point on a wave (10.1)

    crust

    the uppermost layer of the Earth, ranging in thickness from about 5 km (in the oceans) to over 50 km (on the continents) (3.2)

    deep water wave

    a wave above a water depth greater than half of its wavelength (10.1)

    delta

    large, often triangular accumulation of sediment near the mouth of a river (13.4)

    density

    mass per unit volume of a substance (e.g., g/cubic cm) (6.3)

    destructive interference

    where the interaction of multiple waves creates waves smaller than any of the component waves (10.2)

    diatom

    photosynthetic algae that make their tests (shells) from silica (7.2)

    diatomaceous earth

    powdery sediment composed of silica diatom tests (12.3)

    differentiation

    the un-mixing of a magma, typically by the physical separation of minerals that crystallize early and settle towards the bottom (3.1)

    dinoflagellate

    photosynthetic algae characterized by the presence of flagella and a cellulose test (shell) (7.2)

    discoaster

    an extinct form of single-celled algae that produced calcareous tests that can still be found in some marine sediments (12.3)

    diurnal tide

    a tidal cycle with only one high and one low tide per day (11.3)

    divergent boundary

    a plate boundary at which the two plates are moving away from each other (4.5)

    doldrums

    areas of low pressure and weak winds along the equator (8.2)

    domed iceberg

    iceberg with a rounded top (14.2)

    downwelling

    process by which surface water is forced downwards (9.5)

    drowned river valley estuary

    an estuary formed when sea level rises and submerges a river valley (also known as a coastal plain estuary) (13.6)

    drydock iceberg

    iceberg with a water-covered channel running through it (14.2)

    dysphotic zone

    depths of the water column where there is some light penetration, but not enough to support photosynthesis; corresponds to the mesopelagic zone, 200-1000 m. Also known as the twilight zone (1.3)

    ebb current

    current created by an outgoing tide (11.3)

    eccentricity

    in the context of Milankovitch Cycles, the degree to which the Sun is offset from the geometric center of the Earth’s orbit (8.5)

    eddy

    a rotating water mass (9.2)

    electron

    a sub-atomic particle of essentially no mass and a single negative charge (5.1)

    epicenter

    the location on the surface vertically above the location (i.e., “hypocenter” or “focus”) where an earthquake takes place (4.8)

    epipelagic zone

    the upper layer of water (0 to 200 m) in areas of the open ocean (1.3)

    estuary

    a partially enclosed body of water where seawater is diluted by freshwater input (13.6)

    euphotic zone

    the upper regions of the ocean where there is enough light to support photosynthesis; approximately 0-200 m; also called the photic zone (1.2)

    eustatic sea level change

    sea level change related to a change in the volume of the oceans, typically because of an increase or decrease in the amount of glacial ice on land (13.7)

    evaporites

    hydrogenous sediments that form when seawater evaporates (12.4)

    fast ice

    ice sheets that are attached to land (14.1) 

    fault

    a boundary in rock or sediment along which displacement has taken place (4.7)

    fecal express

    small particles reach the seafloor much faster when incorporated into large fecal pellets than if they sank on their own (12.3)

    feedback

    a process by which the physical effects of a climate forcing can have other effects (either negative or positive) on the climate (8.5)

    fetch

    the distance over which wind blows to form waves (10.2)

    firn

    the granular transitional state between snow and ice within a glacier (14.2)

    fjord

    a deep, U-shaped estuary that was carved out by advancing glaciers (13.6)

    flood current

    current created by an incoming tide (11.3)

    flushing time

    the time it would take for all of the fresh water in an estuary to be replaced by runoff of new water (13.6)

    focus (earthquake)

    the actual point below surface at which an earthquake takes place (equivalent to hypocenter) (4.6)

    foraminifera

    a single-celled protist with a shell that is typically made of calcium carbonate (12.3)

    foreshore

    the part of a beach between the high tide and low tide lines (13.1)

    frazil

    small, needle-like crystals in the first stages of sea ice formation (14.1)

    frequency

    the number of waves that pass a point in a given amount of time (10.1)

    fringing reef

    a reef adjacent to a shoreline where there is either a very narrow back reef area or none at all (in which case the reef is effectively attached to the shore) (4.10)

    frost line

    in the context of planetary systems the boundary beyond which volatile components (e.g., water, carbon dioxide, methane, ammonia etc.) are frozen (3.1)

    galaxy

    a gravitationally-bound system of stars and interstellar matter (3.1)

    gas giant

    a large planet composed mostly of hydrogen and helium (e.g. Jupiter) (3.1)

    geostrophic flow

    circular currents created from the balance between gravity- and Ekman-driven flow (9.3)

    giant impact hypothesis

    the theory that the Moon formed when a Mars-sized planet (Theia) collided with the Earth at 4.5 billion years ago (3.1)

    glacial groove

    scratches and grooves carved into bedrock from rocks carried by moving glaciers (4.1)

    glacial ice

    ice formed from the accumulation and compression of snow into glaciers (14.1)

    glacial period

    a period of Earth’s history during which glacial ice was present over a sufficient extent to have left recognizable evidence (4.1)

    glacier

    a long lasting (centuries or more) body of ice on land that moves under its own weight (4.1)

    granite

    an igneous (formed from cooling magma) rock that comprises much of the continental crust (3.2)

    granule

    a sedimentary particle ranging in size from 2 to 4 mm in diameter (12.1)

    grease ice

    an accumulation of frazil to create a slushy consistency in sea ice formation (14.1)

    greenhouse effect

    in the context of climate, the ability of an atmosphere to absorb infrared radiation due to the presence of greenhouse gases (8.1)

    greenhouse gas

    a gaseous molecule with 3 or more atoms that is able to absorb infrared radiation (8.1)

    groin (groyne)

    a man-made structure extending from the shore built to deflect the energy of waves (13.5)

    groin field

    a series of groins along a beach (13.5)

    gross primary production

    the total amount of organic material created by primary producers (7.1) 

    groundwater

    water that lies beneath the surface of the ground (5.2)

    guyot

    a flat-topped seamount (also called a tablemount) (4.9)

    gyre

    a large circular ocean surface current (9.1)

    hadal zone

    the region of the seafloor below 6000 m (1.3)

    hadopelagic (hadalpelagic) zone

    region of the open ocean with water depths greater than 6000 m (1.3)

    halite

    NaCl, a mineral also known as table salt (12.4)

    halocline

    where there is a dramatic change in salinity over a small change in depth (5.3)

    hard stabilization

    the building of physical structures to prevent the erosion of beaches and shorelines (13.5)

    harmful algal bloom (HAB)

    when phytoplankton appear in very high concentrations with potentially hazardous consequences such as mass die-offs or toxicity (7.2)

    headland

    a point of land extending out to sea (13.3)

    heat budget

    the balance between the amount of heat entering and leaving the Earth (8.1)

    heat capacity

    the amount of heat needed to change a substance’s temperature by one degree (5.1)

    high pressure

    in atmospheric terms, a region of descending air, increasing the atmospheric pressure. Winds blow away from high pressure zones (8.3)

    highly stratified estuary

    a deep estuary with some mixing at the surface, but little mixing at depth (13.6)

    homolosine projection

    a map projection where area is retained, but there are interruptions to the continents or oceans (2.4)

    horse latitudes

    areas of high pressure and weak winds around 30 degrees latitude in both hemispheres (8.2)

    hot spot

    the surface area of volcanism and high heat flow above a mantle plume (4.9)

    hydrogen bond

    a weak bond between two molecules due to the electrostatic attraction of a proton in one molecule to the negative polar end of the other molecule (5.1)

    hydrogenous sediment

    sediments formed from the precipitation of dissolved substances (12.4)

    hydrological cycle

    the cycling of water through the ocean, atmosphere, lakes, organisms, and other reservoirs (5.2)

    hydrothermal vent

    area of the seafloor where superheated water seeps out of the crust (4.11)

    hypocenter

    the actual point below surface at which an earthquake takes place (equivalent to focus) (4.8)

    hypoxia

    a condition with low dissolved oxygen, usually defined as oxygen levels below 2 mg/L (5.4)

    ice field

    an area covered by ice floes (14.1)

    ice floe

    a relatively large piece of floating sea ice (14.1)

    ice giant

    a planet that is comprised mainly of gases heavier than hydrogen and helium, including oxygen, carbon, nitrogen, and sulfur (e.g., Uranus and Neptune) (3.1)

    iceberg

    a large, floating piece of glacial ice (14.2)

    inner core

    the solid metal mass at the center of the Earth, extending 1200 km from the center (3.2)

    insolation

    a measure of the intensity of solar energy at a specific location or time (expressed in W/square m) (8.5)

    intermediate wave

    a wave in a water depth between 1/2 and 1/20 its wavelength (10.1)

    internal wave

    waves that form below the surface at the interface between water masses of different densities (10.1)

    intertidal zone

    the region of a coast between the high and low tide lines. Also called the littoral zone (1.3)

    ion

    an atom or molecule that has either gained or lost electrons and has thus become charged (5.1)

    island arc

    long chains of volcanic islands found along convergent tectonic plate boundaries (4.6)

    isostasy

    the equilibrium position reached by a block of crust floating on the underlying fluid mantle (3.2)

    isostatic sea level change

    the effect on relative sea level of a vertical movement of the crust resulting from a change in the mass of the crust (e.g., from losing or gaining ice) (13.7)

    jetty

    a long structure built to protect a harbor from filling with sand due to longshore transport (13.5)

    ka

    (kiloannus) thousands of years before the present

    kinetic energy

    the energy that an object possesses due to its motion (5.1)

    knot

    one knot (kt) = 1 nautical mile per hour = 1.15 mph = 1.85 kph

    land breeze

    winds blowing from land towards the ocean (8.3)

    latent heat of fusion

    the heat required to change a substance from solid to liquid; 80 cal/g in the case of ice melting to water (5.1)

    latent heat of vaporization

    the heat required change a substance from liquid to gas; 540 cal/g to turn water into vapor (5.1)

    latitude

    the distance north or south of the equator, measured as an angle from the equator (2.1)

    lithification

    the conversion of unconsolidated sediments into rock by compaction and cementation (12.1)

    lithogenous sediment

    sediment derived from preexisting rock (12.2)

    lithosphere

    the rigid outer part of the Earth, including the crust and the mantle down to a depth of about 100 km (3.2)

    littoral drift

    the movement of sediment along a shoreline resulting from a longshore current and also from the swash and backwash on a beach face (another name for longshore transport) (13.2)

    littoral zone

    the region of a coast between the high and low tide lines. Also called the intertidal zone (1.3)

    longitude

    measurement of distance east or west of the prime meridian, expressed as an angle (2.1)

    longshore bar

    an offshore deposit of sand parallel to the shoreline (13.1)

    longshore current

    the movement of water parallel to a shoreline produced by the approach of waves at an angle to the shore (13.2)

    longshore transport

    the movement of sediment along a shoreline resulting from a longshore current and also from the swash and backwash on a beach face. Also known as littoral drift (13.2)

    low pressure

    in terms of the atmosphere, a region of rising air, lowering the atmospheric pressure. Winds blow towards low pressure regions, which are often characterized by precipitation from rising, cooling, condensing air (8.3)

    low tide terrace

    another name for the beach face (13.1)

    lysocline

    the depths where the rate of calcium carbonate dissolution increases dramatically over surface waters (12.6)

    magma

    molten rock typically dominated by silica (3.2)

    magnetic dip

    the angle of the magnetic field within a rock, relative to the horizontal; may be used to infer the latitude where the rock was first formed (4.2)

    magnitude

    a measure of the amount of energy released by an earthquake (4.8)

    major ions

    the six ions that comprise over 99% of the ions in the ocean (chloride, sodium, sulfate, magnesium, calcium, potassium) (5.3)

    manganese nodule

    spherical accumulations of manganese and other metals that form slowly through precipitation on the seafloor (12.4)

    mantle

    the middle layer of the Earth, dominated by iron and magnesium rich silicate minerals and extending for about 2900 km from the base of the crust to the top of the core (3.2)

    mantle convection

    movements in the mantle from rising and sinking mantle material as it heats and cools (4.3)

    mantle plume

    a plume of hot rock (not magma) that rises through the mantle (either from the base or from part way up) and reaches the surface where it spreads out and also leads to hot-spot volcanism (4.9)

    maturity

    how long sediment particles have been transported by water or other vectors (12.1)

    meander

    the sinuous path taken by a current, such as the Gulf Stream (9.2)

    mesopelagic zone

    the upper middle zone of the open ocean extending from 200 to 1000 m depth (1.3)

    meteoroid

    a fragment of either stony or metallic debris in space (12.5)

    methane hydrate

    a combination of water ice and methane in which the methane is trapped inside “cages” in the ice (12.4)

    mid-ocean ridge

    an underwater mountain system along divergent plate boundaries, formed by plate tectonics (4.5)

    mixed interference

    where the interaction of multiple waves creates both constructive and destructive interference and an irregular surface pattern (10.2)

    mixed layer

    the topmost layer of the ocean, where winds, waves, and currents mix the water so that conditions are relatively constant; approximately the top 100 m (5.3)

    mixed semidiurnal tide

    a tidal cycle with two high and two low tides per day, each of different heights (11.3)

    nautical mile

    a distance equal to one minute of latitude; equivalent to 1.15 land miles or 1.85 km (2.1)

    neap tide

    the period of minimum tidal range when the Earth is perpendicular to the sun and moon (11.1)

    nearshore

    the part of a beach from the low tide line to the depth where wave action is no longer influenced by the bottom, i.e. to where the depth exceeds the wave base (13.1)

    nebula

    a cloud of interstellar dust and gases (3.1)

    negative feedback

    a process that results in a decrease in that process (in the context of climate change it is a process that reduces the change in climate, such as the enhanced growth of vegetation in response to an increase in atmospheric carbon dioxide) (8.5)

    neritic

    the marine pelagic province from the low tide line to the shelf break (1.3)

    net production

    total primary production minus the organic compounds used up by respiration by the producers (7.1)

    new production

    primary production supported by nutrients brought in from outside of the local ecosystem (7.1)

    nilas

    a thin surface sheet of sea ice (14.1)

    non-conservative ions

    ions in seawater whose proportions fluctuate with changes in salinity (5.3)

    non-tabular iceberg

    an iceberg with any shape other than tabular (14.2)

    nutrient

    in the context of primary production, substances required by photosynthetic organisms to undergo growth and reproduction (5.6)

    nutrient-like element

    elements that have a similar vertical profile to nutrients; low amounts at the surface, increased abundance at depth (5.7)

    obliquity

    in the context of Milankovitch Cycles, the angle of the tilt of the Earth’s rotational axis with respect to the plane of its orbit around the Sun (8.5)

    ocean acidification

    where the overall pH of the ocean declines, likely due to an increased amount of carbon dioxide in the ocean (5.5)

    oceanic

    the marine pelagic province representing the open ocean regions, i.e. beyond the neritic zone (1.3)

    oceanic crust

    the Earth’s crust underlying the oceans (as opposed to continental crust) (3.2)

    offshore

    the beach zone beyond the nearshore region (13.1)

    oolite

    a small (approximately 1 mm) sphere of calcite formed in areas of tropical shallow marine water (12.4)

    ooze

    a sediment composed of >30% biogenous material (12.3)

    outer core

    the layer of the inner Earth extending 2300 km from the top of the inner core to the bottom of the mantle, composed of fluid metal alloys (3.2)

    outgassing

    where dissolved substances in magmas are released as gases when the pressure is reduced (5.2)

    overturning

    the vertical cycling within a body of water, where denser water sinks and less dense water floats to the surface (5.1)

    oxygen minimum layer

    region of ocean depths where dissolved oxygen is at its lowest level; usually around 1000 m for the open ocean (5.4)

    p-wave

    a seismic body wave that is characterized by deformation of the rock in the same direction that the wave is propagating (compressional vibration) (3.3)

    pack ice

    free-floating ice floes (14.1) 

    paleomagnetic

    past variations in the intensity and polarity of the Earth’s magnetic field (4.2)

    pancake ice

    small, rounded, thin pieces of sea ice that will freeze together to form an ice floe (14.1)

    partially mixed estuary

    where salinity increases from the head to the mouth, but there is also a slight increase in salinity with depth at any point; also called a slightly stratified estuary (13.6)

    passive continental margin

    a boundary between a continent and an ocean at which there is no tectonic activity (e.g., the eastern edge of North America) (1.2)

    pebble

    a sedimentary particle ranging in size from 2 to 64 mm (includes granule) (12.1)

    pelagic

    relating to the open ocean (1.3)

    period

    the time it takes for a complete wave to pass a given point (10.1)

    phase change

    the change of state between a solid, liquid, or gas (8.1)

    photic zone

    the upper regions of the ocean where there is enough light to support photosynthesis; approximately 0-200 m; also called the euphotic zone (1.2)

    photosynthesis

    the production of organic compounds from carbon dioxide and water, using sunlight as an energy source (5.5)

    physiographic projection

    map projection presenting bathymetry or altitude data as a 3D relief map (2.3)

    phytoplankton

    drifting, usually single-celled algae that undergo photosynthesis (7.1)

    picoplankton

    planktonic bacteria (7.2)

    pinnacled iceberg

    an iceberg with one or more tall spires (14.2)

    planisphere projection

    map projection that keeps latitude horizontal, but shows some convergence of longitude (2.3)

    plankton

    an organism that cannot swim effectively, so it drifts with the currents (7.1)

    plate

    a region of the lithosphere that is considered to be moving across the surface of the Earth as a single unit (4.1)

    plate tectonics

    the concept that the Earth’s crust and upper mantle (lithosphere) is divided into a number of plates that move independently on the surface and interact with each other at their boundaries (4.1)

    plunging breaker

    a breaking wave on moderately-steep beaches that curls over on itself as it breaks (10.3)

    polar easterlies

    the dominant wind bands between the poles and 60 degrees latitude (8.2)

    polar front

    the boundary between the polar cell and the Ferrel cell around the 60 latitude in each hemisphere (8.2)

    polar molecule

    a molecule where the electrons are not distributed equally, leading to a charge imbalance across the molecule; portions of the molecule are slightly positive while other portions are slightly negative (5.1)

    polar wandering path

    a path of varying magnetic pole positions defined by paleomagnetic data (in fact it is now understood that the continents have wandered, not the poles, so a more appropriate terms is “apparent polar wandering path”) (4.2)

    polyna

    an area of persistent open water in areas otherwise covered with ice (14.1)

    positive feedback

    a process that results in an increase in that process (in the context of climate change it is a process that enhances the change in climate, such as the reduced reflectivity of the Earth’s surface when ice melts) (8.5)

    ppt

    parts per thousand

    practical salinity unit (PSU)

    a unitless measure of salinity equal to parts per thousand (5.3)

    precession

    in the context of Milankovitch Cycles, the variation in the direction at which the Earth’s rotational axis is pointing (8.5)

    pressure ridge

    jagged ridges created from colliding and buckling ice floes (14.1)

    primary production

    the synthesis of organic compounds from aqueous carbon dioxide by plants, algae, and bacteria (7.1)

    protoplanetary disk

    a rotating cloud of gas and dust surrounding a young star (3.1)

    pycnocline

    a region in the water column where there is a large change in density over a small change in depth (6.3)

    quartz

    a mineral composed of silicon and oxygen atoms in the ratio of 1 Si:2 O; one of the most abundant minerals in the Earth's surface (12.1)

    radiation

    the emission of energy in the form of electromagnetic waves (8.1)

    radiolaria

    microscopic (0.1 to 0.2 mm) marine protozoa that produce silica shells (12.3)

    rain shadow

    arid conditions behind a mountain range, as rising air on the other side of the mountain caused rain, leaving only dry air to descend back down the mountain (8.3)

    reef

    a mound of carbonate formed in shallow tropical marine environments by corals, algae and a wide range of other organisms (4.10)

    regenerated production

    primary production resulting from the recycling of nutrients within an ecosystem (7.1)

    remnant magnetism

    magnetism of a body of rock that formed at the time the rock formed and is consistent with the magnetic field orientation that existed at that time and place (4.2)

    residence time

    the average amount of time an element will remain in the ocean before being removed (5.2)

    restoring force

    the force that opposes a wave-generating force and attempts to return the sea surface to the still water level (10.2)

    ridge push

    the concept that at least part of the mechanism of plate motion is the push of oceanic lithosphere down from a ridge area (4.3)

    rift valley

    a valley created when crust subsides along a divergent plate boundary (4.5)

    rip current

    a strong flow of water outward from a beach (13.2)

    rogue wave

    an exceptionally large wave arising among a series of smaller waves (10.2)

    rule of constant proportions

    the major ions in seawater are always found in the same proportions, regardless of overall salinity (5.3)

    runoff

    flow of water down a slope, either across the ground surface, or within a series of channels (12.2)

    s-wave

    a seismic body wave that is characterized by deformation of the rock perpendicular to the direction that the wave is propagating (3.3)

    salinity

    the concentration of dissolved ions in water (5.3)

    salt wedge estuary

    an estuary with mostly fresh surface water, and a wedge of seawater intruding along the bottom (13.6)

    sand

    a mineral or rock fragment ranging in size from 1/16th to 2 mm (12.1)

    saturation

    the amount of a substance currently dissolved in the water, relative to the maximum possible content (5.4)

    scarp

    a short, steep wall carved out by wave action between the foreshore and the berm of a beach (13.1)

    scavenged element

    elements whose vertical profiles show high abundance at the surface and declining concentrations at depth as they are removed by sinking particles (5.7)

    sea breeze

    winds blowing from the ocean towards the land (8.3)

    sea cave

    a shallow cave formed on a rocky shore by wave erosion (13.3)

    sea cliff

    a coastal escarpment that is typically eroding inland as a result of wave action (13.3)

    sea ice

    ice formed from the freezing of seawater (14.1)

    sea stack

    a prominent rocky island that is a remnant of the erosion of a headland (13.3)

    sea state

    describes the current wave conditions in an area (10.2)

    seafloor spreading

    the formation of new oceanic crust by volcanism at a divergent plate boundary (4.5)

    seamount

    a submerged mountain rising from the seafloor (4.9)

    seawall

    a wall built against a sea cliff or dune to prevent erosion from wave action (13.5)

    sediments

    unconsolidated particles of mineral or rock that settle to the seafloor (12.1)

    seismic

    pertaining to earthquakes (3.3)

    seismology

    the study of vibrations within the Earth (3.3)

    semidiurnal tide

    a tidal cycle with two high and two low tides per day, each of roughly equal heights (11.3)

    shallow water wave

    a wave in water with a depth less than 1/20 of the wavelength (10.1)

    shelf break

    the boundary between the continental shelf and continental slope, where the angle of the seafloor begins to get steeper (1.2)

    silica

    a form of the mineral quartz (7.2)

    siliceous sediment

    sediment dominated by particles of silica, often from the shells of marine organisms (7.2)

    silt

    sedimentary particles ranging is size from 1/256th to 1/16th of a mm (12.1)

    slab pull

    the concept that at least part of the mechanism of plate motion is the pull of oceanic lithosphere down into the mantle (4.3)

    slack tide

    period of little water movement between an incoming and outgoing tide (11.3)

    slightly stratified estuary

    where salinity increases from the head to the mouth, but there is also a slight increase in salinity with depth at any point; also called a partially mixed estuary (13.6)

    snow line

    in astronomy the radius around a star at which represents the boundary between gases (or liquids) and solids (3.1)

    solar system

    a star and the planets surrounding it (3.1)

    solar wind

    a stream of ionized (charged) particles away from the Sun (3.1)

    solubility

    the amount of a dissolved substance that water can hold under a particular set of conditions, which are usually defined as 0 degrees C and 1 atmosphere of pressure (5.4)

    sonar

    acronym for sound navigation and ranging; a method of using sound echoes to detect objects (1.4)

    sorting

    how uniform the particles of a sediment are in terms of size (12.1)

    sounding

    a single measurement of ocean depth (1.4)

    specific heat

    the heat required to raise the temperature of 1 g of a substance by 1 degree C (5.1)

    spherule

    a microscopic piece of space dust (12.5)

    spilling breaker

    a breaker on relatively flat beaches that slowly increases its height and collapses (10.3)

    spit

    a sand or coarser deposit extending from shore out into open water (13.4)

    splash wave

    a wave formed when something falls into the ocean and creates a splash (10.1)

    spring tide

    the period of maximum tidal range when the moon, sun and Earth are aligned (11.1)

    stable gas

    unreactive gases that dissolve in seawater (5.7)

    steady state

    where a system shows no net change, as input equals output (5.2)

    still water level

    where the water surface would be if there were no waves present and the sea was completely calm (10.1)

    storm surge

    an area of high water that moves with storm systems (8.4)

    subducted

    when part of a plate is forced beneath another plate along a subduction zone (4.3)

    subduction zone

    the sloping region along which a tectonic plate descends into the mantle beneath another plate (4.6)

    subittoral zone

    the region of a coast from the low tide line to the end of the continental shelf (1.3)

    supralittoral zone

    the region of a coast above the high tide line (1.3)

    surf beat

    an irregular surface wave pattern caused by mixed interference (10.2)

    surf zone

    the near-shore zone where waves are breaking into surf (13.1)

    surface tension

    where a cohesive layer forms on the water surface due to attraction between water molecules (5.1)

    surging breaker

    waves that break on steep beaches with a very sudden increase in height and sudden collapse right on the beach (10.3)

    swash

    the upward motion of a wave on a beach (typically takes place at the same angle that the waves are approaching the shore) (13.1)

    swell

    regular, long-period waves that have sorted themselves based on speed (10.2)

    tablemount

    a flat-topped seamount (also called a guyot) (4.9)

    tabular iceberg

    flat-topped, steep-sided iceberg with a length greater than five times the height (14.2)

    tectonic estuary

    an estuary formed from flooding following the tectonic subsidence of land (13.6)

    tectonic plate

    a region of the lithosphere that is considered to be moving across the surface of the Earth as a single unit (4.4)

    tektite

    solidified glass fragments ejected during meteorite impacts (12.5)

    terrestrial planet

    a planet with a rocky mantle and crust and metallic core (e.g., Earth) (3.1)

    terrigenous sediment

    referring to sedimentary particles that originated on a continent (12.2)

    test

    the shell-like hard parts (either silica or carbonate) of small organisms such as radiolarians and foraminifera (12.3)

    thermal expansion

    the increase in the volume of a body water as its temperature rises and its density decreases (13.7)

    thermocline

    a region in the water column where there is a dramatic change in temperature over a small change in depth (6.2)

    thermohaline circulation

    deep ocean circulation driven by differences in water density (9.8)

    tidal bore

    a wave that moves up a river with an incoming tide (11.3)

    tidal day

    the amount of time between a tide on one day and the same tide the following day (11.2)

    tidal range

    the difference in height between the high and low tides (11.1)

    tidal volume / tidal prism

    the volume difference of an area between low and high tides (11.3)

    tombolo

    a sand or coarser deposit connecting an island or rocky prominence to a larger body of land (13.4)

    trade winds

    prevailing wind bands between the equator and 30 degrees latitude (8.2)

    transform boundary

    a boundary between two plates that are moving horizontally with respect to each other (4.5)

    transform fault

    a type of fault in which two pieces of crust slide past one another (4.5)

    trough

    the lowest point of a wave (10.1)

    tsunami

    a long-wavelength wave produced by the vertical motion of the floor of the ocean, typically related either to an earthquake or other submarine seismic event (10.1)

    turbidity current

    a current moving down downhill along the bottom, driven by the weight of the sediment within it (1.2)

    twilight zone

    depths of the water column where there is some light penetration, but not enough to support photosynthesis; corresponds to the mesopelagic zone, 200-1000 m. Also known as the dysphotic zone (1.3)

    upwelling

    process by which deeper water is brought to the surface (9.5)

    vertically-mixed estuary

    estuary with complete mixing of fresh and salt water, where salinity is constant at all depths in a particular location but increases towards the estuary mouth; also called a well-mixed estuary (13.6)

    water mass

    a volume of seawater with a distinctive density as a result of its unique profile of temperature and salinity (9.8)

    wave base

    the depth of water that is affected by the sub-surface orbital motion of wave action (approximately one-half of the wavelength) (10.1)

    wave height

    the distance between the crest and trough of a wave (10.1)

    wave steepness

    the ratio of wave height to wavelength (10.1)

    wave-cut platform/terrace

    a nearly-horizontal bench of rock eroded by waves within the surf zone (13.3)

    wavelength

    the distance between the crests of two waves (10.1)

    weathering

    a range of processes taking place in the surface environment, through which solid rock is transformed into sediment and ions in solution (12.2)

    wedge iceberg

    iceberg with a steep face next to a more gradually sloping side (14.2)

    well-mixed estuary

    estuary with complete mixing of fresh and salt water, where salinity is constant at all depths in a particular location but increases towards the estuary mouth; also called a vertically-mixed estuary (13.6)

    westerlies

    the dominant wind bands between 30 and 60 degrees latitude in each hemisphere (8.2)

    western intensification

    currents on the western side of a gyre are faster, deeper, and narrower than currents on the eastern side (9.4) 

    zooplankton

    small, drifting carnivorous organisms (7.1)