GLOSSARY

abyssal plain

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

abyssal zone

the region of the seafloor between 4000-6000 m

abyssopelagic zone

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

accretion (planetary)

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

active continental margin

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

aeolian

processes related to transportation and deposition of sediments by wind

albedo

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

amphidromic circulation

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

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

anoxia

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

Antarctic Bottom Water

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

anthropogenic

resulting from the influence of humans

aphotic zone

depths beyond 1000 m where there is no light penetration

arch

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

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

atmospheric wave

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

atoll

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

backshore

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

backwash

the wash of wave water down the slope of a beach

bar-built estuary

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

barrier island

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

barrier reef

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

barycenter

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

basalt

a volcanic rock that makes up much of the oceanic crust

bathyal zone

the region of the seafloor from the shelf break to 4000 m

bathymetry

pertains to measuring the depths of the ocean

bathypelagic zone

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

baymouth bar

a spit that extends across the mouth of a bay

beach face

the area of a beach between the high and low tide lines

Beaufort scale

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

benthic

refers to the environment of the seafloor

benthos

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

berm

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

big-bang theory

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

biogenous sediment

sediment created from the remains of organisms

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

blowhole

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

body wave

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

boulder

a sediment with a grain diameter of at least 256 mm

boundary currents

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

Boyle’s Law

the volume of a gas is inversely proportional to the pressure

brackish

seawater of low salinity; part fresh water, part seawater

breaker

an unstable wave that has collapsed

breakwater

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

buffer

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

calcareous sediment

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

calving

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

capillary waves

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

carbonate compensation depth

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

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

celerity

the speed of a wave

chemosynthesis

the creation of organic compounds using the energy from inorganic chemical reactions

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

clay

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

climate feedback

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

climate forcing

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

coastal plain estuary

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

coastal straightening

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

cobble

sediment particle that is between 64 and 256 mm in diameter

coccolithophore

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

compensation depth

the depth where the rate of photosynthesis equals the rate of respiration

conduction

the transfer of heat through direct contact

conservative ions

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

constructive interference

where the interaction of multiple waves creates waves larger than any of the component waves

continental crust

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

continental drift

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

continental margin

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

continental rise

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

continental shelf

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

continental slope

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

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

convergent boundary

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

core

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

core-mantle boundary

the boundary, at 2900 km depth, between the mantle and the core

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

cosmogenous sediment

sediment derived from extraterrestrial sources

crest

the highest point on a wave

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

crust

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

deep water wave

a wave above a water depth greater than half of its wavelength

delta

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

denitrification

where nitrate is converted to molecular nitrogen through a series of intermediate nitrogen oxide products

density

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

destructive interference

where the interaction of multiple waves creates waves smaller than any of the component waves

diatom

photosynthetic algae that make their tests (shells) from silica

diatomaceous earth

powdery sediment composed of silica diatom tests

differentiation

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

dinoflagellate

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

discoaster

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

diurnal tide

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

divergent boundary

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

doldrums

areas of low pressure and weak winds along the equator

domed iceberg

iceberg with a rounded top

downwelling

process by which surface water is forced downwards

drowned river valley estuary

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

drydock iceberg

iceberg with a water-covered channel running through it

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

ebb current

current created by an outgoing tide

eccentricity

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

eddy

a rotating water mass

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

Ekman transport

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

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

El Niño-Southern Oscillation (ENSO)

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

electron

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

Eocene

a geological epoch lasting from 56 to 33.9 million years ago

epicenter

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

epipelagic zone

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

estuary

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

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

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

evaporites

hydrogenous sediments that form when seawater evaporates

fast ice

ice sheets that are attached to land

fault

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

fecal express

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

feedback

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

Ferrel Cell

the atmospheric convection cells between 30 and 60 degrees latitude

fetch

the distance over which wind blows to form waves

firn

the granular transitional state between snow and ice within a glacier

fjord

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

flood current

current created by an incoming tide

flushing time

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

focus (earthquake)

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

foraminifera

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

foreshore

the part of a beach between the high tide and low tide lines

frazil

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

frequency

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

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)

frost line

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

Ga

(gigaannus) billions of years before the present

galaxy

a gravitationally-bound system of stars and interstellar matter

gas giant

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

geostrophic flow

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

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

gill rakers

tiny hairs in fish mouths that extract plankton from the water

glacial groove

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

glacial ice

ice formed from the accumulation and compression of snow into glaciers

glacial period

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

glacier

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

granite

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

granule

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

grease ice

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

greenhouse effect

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

greenhouse gas

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

groin (groyne)

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

groin field

a series of groins along a beach

gross primary production

the total amount of organic material created by primary producers

groundwater

water that lies beneath the surface of the ground

Gulf Stream

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

guyot

a flat-topped seamount (also called a tablemount)

gyre

a large circular ocean surface current

hadal zone

the region of the seafloor below 6000 m

Hadley Cell

the atmospheric convection cells between the equator and 30 degrees latitude

hadopelagic (hadalpelagic) zone

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

halite

NaCl, a mineral also known as table salt

halocline

where there is a dramatic change in salinity over a small change in depth

hard stabilization

the building of physical structures to prevent the erosion of beaches and shorelines

harmful algal bloom (HAB)

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

headland

a point of land extending out to sea

heat budget

the balance between the amount of heat entering and leaving the Earth

heat capacity

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

Henry’s Law

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

high pressure

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

highly stratified estuary

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

homolosine projection

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

horse latitudes

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

hot spot

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

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

hydrogenous sediment

sediments formed from the precipitation of dissolved substances

hydrological cycle

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

hydrothermal vent

area of the seafloor where superheated water seeps out of the crust

hypocenter

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

hypoxia

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

ice field

an area covered by ice floes

ice floe

a relatively large piece of floating sea ice

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)

iceberg

a large, floating piece of glacial ice

ichthyology

the study of fish

inner core

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

insolation

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

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

intermediate wave

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

internal wave

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

intertidal zone

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

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

ion

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

island arc

long chains of volcanic islands found along convergent tectonic plate boundaries

isostasy

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

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)

isotope

forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei

jetty

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

Jovian planet

a gas giant

ka

(kiloannus) thousands of years before the present

keystone species

a vital species that is needed to sustain the ecosystem

kinetic energy

the energy that an object possesses due to its motion

knot

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

La Niña

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

land breeze

winds blowing from land towards the ocean

Langmuir circulation

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

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

latent heat of vaporization

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

latitude

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

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

lithification

the conversion of unconsolidated sediments into rock by compaction and cementation

lithogenous sediment

sediment derived from preexisting rock

lithosphere

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

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)

littoral zone

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

longitude

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

longshore bar

an offshore deposit of sand parallel to the shoreline

longshore current

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

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

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

low tide terrace

another name for the beach face

lysocline

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

Ma

(Megaannus) millions of years before the present

magma

molten rock typically dominated by silica

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

magnitude

a measure of the amount of energy released by an earthquake

major ions

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

manganese nodule

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

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

mantle convection

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

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

maturity

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

meander

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

Mercator projection

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

mesopelagic zone

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

Mesozoic

the geological era from about 252 to 66 million years ago

meteoroid

a fragment of either stony or metallic debris in space

methane hydrate

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

mid-ocean ridge

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

Milankovitch cycles

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

mixed interference

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

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

mixed semidiurnal tide

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

Mohorovičić discontinuity (Moho)

the boundary between the crust and the mantle

Mysticetes

baleen whales

nautical mile

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

neap tide

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

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

nebula

a cloud of interstellar dust and gases

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)

neritic

the marine pelagic province from the low tide line to the shelf break

net production

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

new production

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

nilas

a thin surface sheet of sea ice

nitrification

the biological oxidation of ammonia or ammonium to nitrite followed by the conversion of the nitrite to nitrate

nitrogen fixation

the process of converting atmospheric nitrogen gas into nitrogenous compounds like ammonia

non-conservative ions

ions in seawater whose proportions fluctuate with changes in salinity

non-tabular iceberg

an iceberg with any shape other than tabular

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

nutrient

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

nutrient-like element

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

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

ocean acidification

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

oceanic

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

oceanic crust

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

Odontocetes

toothed whales

offshore

the beach zone beyond the nearshore region

oolite

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

ooze

a sediment composed of >30% biogenous material

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

outgassing

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

overturning

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

oxygen minimum layer

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

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)

pack ice

free-floating ice floes

Paleocene

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

paleomagnetic

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

Paleozoic

the geologic era lasting from 541 to 252 million years ago

pancake ice

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

Pangaea

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

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

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)

pebble

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

pelagic

relating to the open ocean

period

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

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

phase change

the change of state between a solid, liquid, or gas

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

photosynthesis

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

physiographic projection

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

phytoplankton

drifting, usually single-celled algae that undergo photosynthesis

picoplankton

planktonic bacteria

pinnacled iceberg

an iceberg with one or more tall spires

planisphere projection

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

plankton

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

plate

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

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

plunging breaker

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

Polar Cell

the atmospheric convection cells between 60 degrees latitude and the pole

polar easterlies

the dominant wind bands between the poles and 60 degrees latitude

polar front

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

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

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”)

polyna

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

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)

ppm

parts per million

ppt

parts per thousand

practical salinity unit (PSU)

a unitless measure of salinity equal to parts per thousand

precession

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

pressure ridge

jagged ridges created from colliding and buckling ice floes

primary production

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

protoplanetary disk

a rotating cloud of gas and dust surrounding a young star

pycnocline

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

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

radiation

the emission of energy in the form of electromagnetic waves

radiolaria

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

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

reef

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

regenerated production

primary production resulting from the recycling of nutrients within an ecosystem

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

residence time

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

restoring force

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

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

rift valley

a valley created when crust subsides along a divergent plate boundary

rip current

a strong flow of water outward from a beach

rogue wave

an exceptionally large wave arising among a series of smaller waves

rule of constant proportions

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

runoff

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

s-wave

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

salinity

the concentration of dissolved ions in water

salt wedge estuary

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

sand

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

saturation

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

scarp

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

scavenged element

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

sea breeze

winds blowing from the ocean towards the land

sea cave

a shallow cave formed on a rocky shore by wave erosion

sea cliff

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

sea ice

ice formed from the freezing of seawater

sea stack

a prominent rocky island that is a remnant of the erosion of a headland

sea state

describes the current wave conditions in an area

seafloor spreading

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

seamount

a submerged mountain rising from the seafloor

seawall

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

sediments

unconsolidated particles of mineral or rock that settle to the seafloor

seismic

pertaining to earthquakes

seismology

the study of vibrations within the Earth

semidiurnal tide

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

shallow water wave

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

shelf break

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

significant wave height (Hs)

the mean height of the largest one-third of the waves in a wave spectrum

silica

a form of the mineral quartz

siliceous sediment

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

silt

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

slab pull

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

slack tide

period of little water movement between an incoming and outgoing tide

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

snow line

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

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

solar system

a star and the planets surrounding it

solar wind

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

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

sonar

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

sorting

how uniform the particles of a sediment are in terms of size

sounding

a single measurement of ocean depth

specific heat

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

spherule

a microscopic piece of space dust

spilling breaker

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

spit

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

splash wave

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

spring tide

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

stable gas

unreactive gases that dissolve in seawater

steady state

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

still water level

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

storm surge

an area of high water that moves with storm systems

subducted

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

subduction zone

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

subittoral zone

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

supralittoral zone

the region of a coast above the high tide line

surf beat

an irregular surface wave pattern caused by mixed interference

surf zone

the near-shore zone where waves are breaking into surf

surface tension

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

surging breaker

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

swash

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

swell

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

tablemount

a flat-topped seamount (also called a guyot)

tabular iceberg

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

tectonic estuary

an estuary formed from flooding following the tectonic subsidence of land

tectonic plate

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

tektite

solidified glass fragments ejected during meteorite impacts

terrestrial planet

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

terrigenous sediment

referring to sedimentary particles that originated on a continent

test

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

thermal expansion

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

thermocline

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

thermohaline circulation

deep ocean circulation driven by differences in water density

tidal bore

a wave that moves up a river with an incoming tide

tidal day

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

tidal range

the difference in height between the high and low tides

tidal volume / tidal prism

the volume difference of an area between low and high tides

tombolo

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

trade winds

prevailing wind bands between the equator and 30 degrees latitude

transform boundary

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

transform fault

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

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

turbidity current

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

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

upwelling

process by which deeper water is brought to the surface

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

water mass

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

wave base

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

wave height

the distance between the crest and trough of a wave

wave steepness

the ratio of wave height to wavelength

wave-cut platform/terrace

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

wavelength

the distance between the crests of two waves

weathering

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

wedge iceberg

iceberg with a steep face next to a more gradually sloping side

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

westerlies

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

western intensification

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

zooplankton

small, drifting carnivorous organisms