Marine Provinces Flashcards
Echo sounders
Device that sends a sound signal (called a long) into the ocean to produce echoes when the sound bounces off any density difference, such as marine organisms or the ocean floor
Precision depth recorder (PDR)
Uses a focused high frequency sound beam to measure depths to a resolution of about 1 meter
Sonar
Acronym for sound navigation and ranging
SeaBeam
First multibeam echo sounder-made it possible for a survey ship to map the features of ocean floor along a strip up 60km
Sea MARC and GLORIA
Side scan sonar systems that can be towed behind a survey ship to produce a strip map of ocean floor bathymetry
Seismic reflection profiles
Low frequency sounds produced by explosions or air guns which penetrate beneath seafloor and reflect off boundaries between different rock or sediment layers
Used for mineral and petroleum exploration
Hypsographic curve
Shows the relationship between the height of the land and the depth of the oceans
Continental margins
Shallow water areas close to continents
Deep-ocean basins
Deep water areas farther from land
Mid-ocean ridge
Shallower areas near the middle of an ocean
Passive continental margin
Imbedded within the interior of lithospheric plates and are therefore not in close proximity to any plate boundary. Therefore they usually lack major tectonic activity
Active continental margins
Associated with lithospheric plate boundaries and are marked by a high degree of tectonic activity.
Two type: convergent and transform
Convergent active margins
Associated with oceanic-continental convergent plate boundaries.
Transform active margins
Less common and associated with transform plate boundaries
Continental shelf
A generally flat zone extending from the shore beneath the ocean surface to a point at which a marked increase in slope angle occurs (shelf break)
Shelf break
A point at which a marked increase in slope angle occurs
Continental slope
Lies beyond the shelf break
Where deep-ocean basins begin
Submarine canyons
The continental slope exhibit submarine canyons
V-shaped in profile view and have branches or tributaries with steep to overhanging walls
Resemble canyons formed on land that are carved by rivers and can be quite large
Turbidity currents
Underwater avalanches of muddy water mixed with rocks and other debris
Continental rise
A transition zone between the continental margin and the deep ocean floor comprised of a huge submerged pile of debris
Graded bedding
Slowing turbidity currents causing suspended material to settle out in a distinctive type of layering. Grades in size upward.
Turbidite deposits
Stacks of graded bedding that compose continental rise
Deep sea fans
Submarine fans
Deposits at the mouths of submarine canyons that are fan shaped
Create continental rise when they merge together along base of continental slope
Bathymetry
The measurement of ocean depths and the charting of the shape or topography the ocean floor
Abyssal plains
Extending from the base of the continental rise into the deep ocean basins are flat depositional surfaces with slopes that average a small fraction of a degree and cover extensive portions of the Deep ocean basins
Suspension settling
Where fine particles accumulate on the ocean floor
Abyssal hills (or seaknolls)
Volcanic features on ocean floor that are less than 100m tall
Continental flood basalts
Volcanic accumulations (igneous provinces) found in continents
Ocean trench
Deep linear scars in the ocean floor, caused by collision of two plates along convergent plate margins
Volcanic arc
The landward side of the trench that may produce islands (islands of Japan-island arc) or volcanic mountain range along margin of a continent (Andes-continental arc)
Back arc spreading center
When an overriding plate gets pulled toward the trench, producing a spreading center behind (landward of) the volcanic arc
Rift Valley
A central downdropped valley along the crest of a mid ocean ridge that is entirely volcanic
Pillow basalts
Smooth rounded lobes of rock that resemble a stack of bed pillows created when hot basaltic lava spills into seafloor and is exposed to cold seawater that chills the margins of the lava.
Ocean ridges
Segments of mid-ocean ridge
Have prominent Rift Valley and steep, rugged slopes
Oceanic rises
Slopes that are gentler and less rugged
