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Cheatography

Geology of Oceans Cheat Sheet (DRAFT) by

GEOS100 - Geology of oceans cheat sheet

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Studying the Ocean Floor

Geophy­sical Methods
  Sonar: depth is establ­ished through reflecting soundwaves from the ocean floor by measuring the velocity of sound waves in water and the time required for the wave to hit the floor.
  Multi-beam sonar: employs multiple signals to map a stretch of the seafloor
Satellites
Submarines
Oceans Network Canada - Generate sonar data into images
Field study through direct observ­ations on land

Active Contin­ental Margins

Contin­ental slope descends abruptly into a deep-ocean trench; Accumu­lation of sediments form an accret­ionary wedge onto the non-su­bdu­cting tectonic plate at a convergent plate boundary.
 

Mid-Oc­eanic Ridges (MOR)

A continuous range of underwater volcanoes that make up 20% of earth's surface; down faulted structures called rift valleys; sea floor spreading at crest of ridges; consists of many layers of basaltic rock.
Structure:
Upper layer - Consisting of pillow lava
Middle layer - Numerous interc­onn­ected sheeted dikes
Lower layer - Gabbro
Gabbro - intrusive equivalent of basalt
 

Topogr­aphic Units

Contin­ental margins
Deep ocean margins
Mid ocean ridges

Passive Contin­ental Margins

Contin­ental slope - marks the seaward edge of the contin­ental shelf; boundary between contin­ental crust and oceanic crust; represents true edge of continent; represents original rift (Pangea splitt­ing); cut by submarine canyons
Contin­ental Rise - at the base of the slope; thick accumu­lation of sediment in deep sea fans, containing turbidites
Submarine canyons - steep sided valley with nearly vertical walls
Deep sea fans - the layer of sediment below the submarine fan
Turbidites - fine grained sediment that was deposited by strong downward flow of water containing high amounts of sediment, called turbidity current