Oceanography Semester 1 Midterm Vocabulary

Unit 1 - Water Planet

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Tropic of Cancer

an imaginary line that circles the Earth at 23.5 degrees north of the equator

Tropic of Capricorn

an imaginary line that circles the Earth at 23.5 degrees South of the equator

Winter Solstice

December 21, shortest day of the year

Summer Solstice

June 21, longest day of the year

Autumnal Equinox

September 21

Vernal Equinox

March 21

Solar Day

every 24 hours, the Earth completes one full rotation

Revolution

occurs every 365 ¼ days

Latitude

lines run from east to west

Longitude

lines run from north to south; all lines of longitude are Great Circles

Parallel

another name for latitude lines

Equator

imaginary line that divides the Earth into the Northern Hemisphere and the Southern Hemisphere

Great Circle

a circle on the earth's surface which has its center in the center of the earth

Prime Meridian

imaginary line that represents 0 degrees longitude

International Date Line

an imaginary line that runs roughly along the 180° longitude in the Pacific Ocean (opposite of Prime Meridian)

Nautical Mile

a unit of measurement used in navigation and is equal to one minute of latitude

Contour

the depth (below sea level) or the elevation (above sea level) with a series of contour lines

Topography

the physical features or characteristics of a surface or area

Bathymetry

the measurement and mapping of the depth and topography of underwater surfaces, such as oceans, seas, and lakes

Physiographic Map

show physical features

Fathom

a unit of measurement used to determine the depth of water

Unit 2 - Geology and Plate Tectonics

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Mineral

naturally occurring, non-living substances

Igneous

forms when molten rock cools and solidifies; extrusive and intrusive

Sedimentary

formed through the accumulation and consolidation of sediments over time; clastic and non-clastic

Metamorphic

forms from the transformation of pre-existing rocks due to high temperature and pressure; foliated and non-foliated

Pangea

the shapes of continents fit together

Continental Drift

plates are moving

Plate Tectonics

plates move independently in different directions, at different times and speds

Lithosphere

crust

Asthenoshpere

mantle

Convection Cell

magma heats, rises, cools, and sinks

Seafloor Spreading

areas where magma pushes up through crust and cools as new land; divergent boundaries only occur at mid-ocean ridges

Magnetic Reversal

the Earth has a magnetic field generated by the core

Transform Fault Boundary

plates slide together; ex. San Andreas Fault

Subduction Zone

a tectonic boundary where two lithospheric plates converge, and one plate is forced beneath the other and into the Earth's mantle

Divergent Plate Boundary

locations where tectonic plates are moving away from each other

Convergent Plate Boundary

a convergent plate boundary is a type of tectonic boundary where two lithospheric plates are moving towards each other; this collision can occur between two oceanic plates, two continental plates, or an oceanic plate and a continental plate

Hot Spot

an area on Earth over a mantle plume or an area under the rocky outer layer of Earth, called the crust, where magma is hotter than surrounding magma; widespread volcanic activity

Geothermal

renewable energy source that has the potential to meet various energy demands; it involves harnessing heat from the Earth's interior to generate electricity or provide heating and cooling

Unit 3 - Bathymetry & Sedimentation

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Continental Margin

area between the edge of land and descension

Continental Shelf

flat (not completely) place between the land and ocean basin; the continental shelf boundary is defined by an abrupt change in slope and a rapid increase in depth (continental shelf break)

Continental Slope

the steep extension to the ocean basin

Submarine Canyons

dramatic features on the continental slope; formed by rivers of melting glaciers

Trenches

located on the sea side of island arcs and created by subductions of a dense oceanic plate and a light continental plate

Abyssal Hills

found on abyssal plains, not high, define features

Guyots

older seamounts that have undergone wave erosion

Echo Sounder

produces a sound that is transmitted out of the hole of the boat, bounces off the bottom and is received again at the hole of the ship

Turbidity Currents

moving flow of sediment and water that travels down through submarine canyons and leaves ripple marks on the floor

Turbidities

layered deposits found along the canyon and abyssal fan

Isobath

underwater contour lines

Contour Line

a line on a map joining points of equal height above or below sea level

Lithogenous Sediment

sediments derived from rock

Biogenous Sediment

sediments derived from the remains of living organisms

Hydrogenous Sediment

produced in seawater by chemical processes

Cosmogenous Sediment

come from the atmosphere

Terrigenous Sediment

derived from the erosion of rocks on land

Ooze

if sediments are made up of more than 30% biogenous sediments

Neritic Sediment

come from land and sea sources, found in shallow waters

Pelagic Sediment

deposited far from land

Dredge Grab Sampler

a net or wire basket that is dragged across the bottom to collect loose material or shells in a random manner

Corer

a weighted hollow pipe with a sharp end that pierces the sediments, providing a cylinder of mud (oldest ↑, newest ↓)

CCD (Calcium Carbonate Compensation Depth)

calcareous deposits are only found to the depth of the approximately 4500m