BATHYMETRY OF THE OCEAN FLOOR

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BATHYMETRY OF THE OCEAN FLOOR
Structures on the ocean floor are mapped by SONAR
- sound navigation and ranging (echo sounding)
(speed of sound in H20)
depth time x 1460 meters/sec 2
(round trip)
sea floor
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Continental Margin the submerged outer edge of a
continent marks the transition between continent
and ocean, composed of shelf, slope rise
a. continental shelf - underwater extension of
the continent, most biologically productive area
because of light availability
b. continental slope sloping transition between
granite of the continent (granite) and the
deep-ocean floor (basalt) - sediments tumbling
down the slope van formturbidity currents which
cut submarine canyons (deep, V-shaped valley
running perpendicular to the shoreline)
c. continental rise wedge of sediments covering
the joint between ocean crust and continental
crust
NOAA
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Ocean Basin
a. abyssal plains - flat, featureless region
similar to a desert common in Atlantic and
Indian Oceans, rare in the Pacific
b. abyssal hill - domes of sediment that shift
like dunes
c. seamount - peaks of volcanic mountains (sea
mountains)
d. guyot - submerged, inactive volcane truncate
d by erosion like plateaus
e. island - seamounts extending out of the water.
They differ from continents because they have no
margins.
Volcanic eruptions create and destroy the terrain.
Hot spots under moving plates cause island arcs
such as the Hawaiian Island chain. Parts of the
chain are still submerged.
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Hawaiis volcano, Mauna Kea, is the highest
mountain on Earth.
Its 31,000 ft. from the Pacific floor -
although only 13,823 ft. of it are above water.
f. trenches arc-shaped depression in the
deep-ocean floor with very steep sides and flat
sediment-filled bottoms, associated with
subduction zones where ocean crust is being
recycled into the mantle
Trenches form a boundary around the Pacific
called the Ring of Fire because of the volcanic
and seismic activity.
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Mt. Everest, at 29,000 ft., could fit into the
Mariana trench and still be 7,000 ft. below sea
level.
g. MOR - 40,000 mile long mountain range where
new oceanic floor is being formed.
Divergent plate boundaries are found in all parts
of the ocean - not just in the middle of the
Atlantic.
NOAA
Iceland is a large section of the MOR extending
above the water.
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h. rift valley down-dropped section of a MOR
occurring at divergent plate boundaries,
outpouring of magma creates new ocean floor
NASA
Oceanic bathymetry is very similar to continental
topography except that continent features are
smaller due to erosion