Oceanography Chapter 3 Test
mid ocean ridge is a _______ plate boundary
divergent
rift valley
down dropped area on crest of ridge
echo soundings
echo sounder or fathometer - reflection of sound signals off ocean floor
what are efficient bathymetric tools? (2)
echo sounding and satellites
how was the mid atlantic ridge discovered?
echo soundings, german ship METEOR
t or f: in turbidity currents, small particles settle first with larger particles setting on top
false
t or f: ridges separate quickly and have gradual slopes compared to a rise
false
t or f: subduction zones move and change over time
false
t or f: PDR is does not make reliable maps
false: PDR produces the first reliable sea floor maps
t or f: the continental shelf is not part of the continent
false: the continental shelf is geologically part of the continent
rise = ______ separation
faster
passive margins have ______ shelves
wider
bathymetry
measure of ocean depth and seafloor topography
bathymetry
measures the vertical distance from the ocean surface to mountains, valleys, plains, and other sea floor features
continental arc are _____
mountain on land (andes mountains
PDR is referred to _____
mowing the lawn
submarine canyons are ______
narrow, deep, v-shaped in profile
mid ocean ridge = ______
new crust
sediment in abyssal plains cover ______
ocean crust irregularities
the study of bathymetry determines _______ and _______
ocean depths and ocean floor topography
where are volcanic arc located?
on non subducted ocean plates
how much does the mid ocean ridge occupy in the deep sea basin?
one third
seismic surveys use
air guns or strong, low-frequency sounds
continental slope is where ____ begin
deep ocean basins
deep ocean basins
deep water areas farther from land
where are abyssal plains well developed?
atlantic and indian oceans
submarine canyons extend to _____
base of continental slope (3500 m or 11,500 ft below sea level)
abyssal plains extend from _______
base on continental rise
how do satellites measure the sea floor?
based on gravitational bulges in sea floor
how is the continental slope marked?
by submarine canyons
how are submarine canyons carved?
by turbidity currents
side scan sonar _____
can be towed behind ship to provide very detailed bathymetric strip map
oceans trenches are the ____ of oceans
deepest part
where do the sediments of turbidity currents go?
deposited at slope base
seismic surveys shoes the
details of ocean structure beneath sea floor and detailed shape and position of boundaries
gloria
device used for side-scan sonar
different seafloor features exist in _______
different oceanographic locations
california's transform active margin has a ______
continental borderland
what are the 3 major ocean provinces?
continental margins, deep-ocean basins, mid-ocean ridge
type of _______ determine ______ features
continental margins, shelf
order of continental margin?
continental shelf, shelf break, continental slope, continental rise, abyssal plain
passive continental margin order of features
continental shelf, shelf break, continental slope, continental rise, abyssal plain
does the continental slope or shelf have a greater shelf?
continental slope (averages 4 degrees but can vary from 1-25 degrees)
2 types of active continental margins
convergent and transform active margins
pacific ring of fire is marked by _____
convergent boundaries
what generates ocean trenches?
convergent margins
hypsographic curve
cumulative plot of area versus depth or elevation
where are most ocean trenches located?
pacific ocean
ocean trenches are located where in the pacific ocean?
pacific ring of fire
where do the majority of world's active volcanoes and earthquakes happen?
pacific ring of fire
most ocean floor features are generated by _______
plate tectonic processes
PDR stands for ______
precision depth recorder
sea floor mapping from space uses _____
satellite measurements
hydrothermal vents are _____
sea floor hot springs
what did PDR help confirm?
sea floor spreading
what are the mid ocean ridge features?
seamounts, pillow lava/basalt, hydrothermal vents
what abyssal plain volcanic peaks are below sea level?
seamounts, tablemounts, guyots, and abyssal hills/seaknolls
abyssal plain volcanic peaks that are at least 1km above sea floor
seamounts, tablemounts, or guyots
abyssal plain volcanic peaks poke through _____
sediment cover
turbidity currents have _____
sediment from continental shelf
seamounts
tall volcanoes
california's margin is a _____
transform active margin
pacific ring of fire are the _______ of pacific ocean
margins
deepest trench
mariana trench (11,000 meters or 36,161 feet)
abyssal plains have _______ of _________ particles
suspension settling, very fine
active continental margins
- associated with convergent or transform plate - much tectonic activity - west coast if US - thin sediment accumulation
transform continental margin
- less common - transform plate boundaries - linear islands, banks, and deep basins close to shore - coastal california along san andreas fault
passive continental margins
- not close to any plate boundary - no major tectonic activity - east coast of US (shallow) - thick sediment accumulation
convergent active margin
- ocean-continent convergent plate boundaries - active continental volcanoes - narrow shelf - offshore trench - islands - western south america
average depth of shelf break
135 meters (443 feet)
how far an the continental shelf reach up to and where?
1500 km (930 miles) in arctic ocean
when was echo sounding created/used?
1925
when was PDR created/used?
1950s
average depth of continental shelf
70 km (43 miles)
how hot do hydrothermal vents get to?
800 degrees F
what does GLORIA stand for?
Geological Long-Range Inclined Acoustical Instrument
what are the modern bathymetry measuring systems?
SONAR, SIDE SCAN SOLAR (GLORIA)
abyssal plain volcanic peaks that are less than 1km above sea floor
abyssal hill/ seaknolls
continental shelf
flat zone from shore to shelf break
PDR is ____
focused high frequency sound beam
continental rise is the _______ in turbidite deposits
graded bedding
where are some of the deepest and flattest parts of earth?
in abyssal plains
mid ocean ridge is the _______ mountain chain
longest
poseidonus
made first sounding in 85 BC
shelf break is where marked _________ occurs
increase in slope angle
what do satellite measurements reveal?
indirectly reveals bathymetry
island arc
island in ocean (Japan)
trenches _______ their position over time
keep
negative of echo soundings
lacks detail and could provide inaccurate view of sea floor. reflects anything in its way
what is the continental slopes topography similar to?
land mountain ranges
sounding
line with heavy weight
soundings
line with heavy weight
hydrothermal vents have _______
seep metal sulfides
what method uses a strong, low frequency sound to measure the shape/position of boundary layers?
seismic survey
continental margins
shallow water areas close to shore
rises have a _____ slope
shallow/gradual
seismic survey
shape and position of boundaries
pillow lavas or pillow basalt
shapes formed when hot basaltic lava quickly cools
hypsographic curve def
shows relationship between height or land and depth of ocean
vents have ______ impact on ________
significant, ocean chemistry
in a continental rise how are the sediments characteristics?
similar to those formed by rivers on land
ridge = ______ separation
slower
what kind of earthquakes doe rift valleys form?
small earthquakes
what does SONAR stand for?
sound navigation and range
what is used when measuring bathymetry?
soundings, poseidonus, fathom
submarine canyons are _______ to ______ walls
steep, overhanging
ridges have a _____ slope
steeper
mid ocean ridge
submarine mountain range
continental rise is the _____
transition between continental crust and oceanic crust
continental rise is marked by ______
turbidite deposits from turbidity current
how do turbidity currents move?
under the influence of gravity
turbidity currents are ____
underwater avalanches mixed with rocks and other debris
fathom
unit of measure (1.8 meters or 6 feet)
hydrothermal vents have _____ ecosystems able to survive without _______
unusual and diverse deep ocean, sunlight
satellite
used to map ocean floor from space
PDR
uses high frequency sound waves to measure ocean depth
abyssal plain volcanic peaks that are above sea level
volcanic islands
what does the mid ocean ridge create?
volcanic/basaltic lava
