esocean Flashcards
Wegener’s continental drift theory findings:
fit of continents
matching of rock units across ocean basins
distribution of fossils
paleoclimate evidence
the study of the “beds” or “floors” of water bodies. foundation of the science of hydrography
Bathymetry
bathymetry refers to:
the ocean’s depth relative to sea level,
although it has come to mean “submarine topography”, or the depths and shapes of
underwater terrain
methods of measuring ocean depth
sounding line, echo sounding, satellite altimetry
method of weighted rope lowered overboard until it touched the ocean
bottom; this old method is time-consuming and inaccurate
sounding line
sonar is used by emitting high frequency sound and listening of the echo from the seafloor. deeper water means longer time for the echo to reach the receiver
echo sounding
profiles the shape of the sea surface by measuring the travel time of a radar pulse from a satellite to the ocean surface and back to the receiver. the shape of the sea surface approximates the shape of the sea floor
satellite altimetry
evidences of seafloor spreading
distribution of seafloor topographic features
sediment thickness
composition of oceanic crust
high heat flow along mid-ocean ridge axes
distribution of submarine earthquakes
magnetic stripes on the seafloor
deep sea drilling results
contemplated that oceans grew from their centres, with molten material
(basalt) oozing up from the Earth’s mantle along the mid ocean ridges, this created new
seafloor which then spread away from the ridge in both directions. one of the “founding fathers” of the unifying theory of plate tectonics.
Harry Hammond Hess
two types of lithospheric crust
continental and oceanic crust
thickness of continental and oceanic lithosphere
continental: 150km
oceanic: 100km
what is plate tectonic theory
proposes that the lithosphere is made up of seven large plates and numerous smaller segments. These plates rest upon the soft layer of asthenosphere. They move relative to each number.
3mmain types of plate boundaries
Divergent, Convergent, Transform Boundaries
two plates are moving apart
divergent boundary
two plates are colliding
convergent boundary
plates slide past each other
transform boundary
what is the wilson cycle
Plate tectonics is cyclic. In 1966, John Tuzo Wilson proposed a cycle that includes continental break-up, drifting, collision and re-assembly of the continent
main phases of the wilson cycle
- Rifting within the supercontinent leads to the opening of new ocean basin and formation of oceanic crust
- Passive margin cools and sinks, and sediment accumulate along the edge.
- Convergence begins, initiating subduction and eventual ocean closure.
- Continent-continent collision forms the next supercontinent.
driving force for plate motion
convection in the mantle
gravity driven mechanisms (slab-pull, ridge-push)
percentage of ocean basin on the planet’s surface
70%
two characteristics of oceanic basin landform:
land that exists under the ocean
land that includes all topographical features
structures of ocean basins
mid-oceanic ridge
ocean trenches
abyssal hill/plain
seamounts
guyot
continental rise
continental shelf
continental slope
structure normally found rising above the ocean floor at the center of the ocean basins
mid-oceanic ridge
long narrow, steep-sided depressions that
contain the greatest depths in the ocean.
ocean trenches
found on the deep ocean floor.
are so flat because they are covered with sediments that have been washed off the surface of the continents for thousands of years.
abyssal hill(found deep)
abyssal plain(flat)
These features can be very large submerged volcanic mountain reaching heights up to 10,000 feet
seamounts
similar to a seamount, but it is submerged volcanic mountain with a flat top
guyot
s feature found gently sloping area before the ocean floor and at the base of the continental slope and formed by emerging accumulates deposits at the mounts of many submarine canyons
continental rise
a shallow, gently sloping part of the continent crust.
continental shelf
This part of the ocean basin extends and slopes after the continental shelf. The boundary between the continental slope and shelf
continental slope
three major provinces of ocean basins
continental margins
deep-ocean basins
oceanic or mid-oceanic ridges
five ocean basins from largest to smallest
Pacific, Atlantic, Indian, Southern and Arctic
includes any change in position, shape/volume of a rock in response to stress
rock deformation
force per unit area applied on rock layers. causes strain on rock layers.
stress
change in shape or volume of the rock that has undergone stress
strain
is not just a function of the amount of stress but also relates to the area over which
the force is applied.
magnitude of stress
stages of deformation
elastic deformation
ductile deformation
fracture deformation
stage of deformation when the strain is reversible, the material returns to its original shape once the stress that deforms it is removed
elastic deformation
occurs when the strain is irreversible –
rock layers/material respond to stress by
bending or deforming without breaking.
ductile deformation
irreversible strain wherein the materials
break because they are mostly brittle.
fracture deformation
material composition and factors that affects the brittle-ductile transition
temperature
confining pressure
rate of strain
low temperature low confining pressure high rate of strain
increases brittleness of rock
high temperature high confining pressure low rate of strain
increase ductile properties of rock
formed when rock layers or materials are deforming plastically under compressive stress, most of these materials do not return to their original shape.
folds
types of folds
monocline
anticline
syncline
overturned
type of fold that occurs when there is a
simple bending of rock layers so that they are no longer horizontal.
monocline
occurs when a fold bends upward.
anticline
occurs when a fold bends downward.
syncline
axial plane inclined to such an extent that the strata on one limb are overturned.
overturned
occur when too much stress is applied to rock layers.
faults
is the energy released during the movement of faults.
earthquake
distance that rocks move sideways a fault.
can be up or down the fault plane which is relative since there is usually no way to know whether both sides moved or only one.
slip
angle that faults lie to the horizontal of the surface of the Earth.
dip
type of faults
dip-slip faults (normal fault-reverse fault)
strike slip fault
oblique slip fault
this type of fault is when the fault’s dip is inclined relative to the horizontal surface
dip-slip fault
when the hanging wall drops down relative to the footwall
normal fault
when the footwall drops down relative to
the hanging wall.
reverse fault
are the vertical fractures where the blocks have mostly moved horizontally.
strike slip fault
fault which has components of dip-slip and strikes slip.
oblique slip fault
any process or phenomena associated with the discharge of molten rock, pyroclastic fragments, or hot water and steam, including
volcanoes, geysers, and fumaroles.
volcanism/vulcanism
a landform that resembles a mountain with
an opening (vent) where magma, lave, ash, gasses, etc. are being released.
volcano
Area in the Circum-Pacific where most of the world’s active volcanoes are found.
Pacific Ring of Fire
mafic to intermediate intrusives
plutonism
mafic to intermediate extrusives
volcanism
materials released during volcanic eruption
gasses (water vapor, CO2, toxic gases such as carbon monoxide, sulfur dioxide, hydrogen sulfide and hydrochloric acid)
liquid(lava)
solid/pyroclastics (volcanic blocks, cinders lapilli, volcanic ash, volcanic dust)
