Download MS1_PNT_GeologicalOceanographyPPT_V01

Continental Margins
•
•
•
Continental shelf: shallowest part of the margin
Continental Slope: a steeper part
Continental Rise: gently sloping region at the
base of the of the continental slope; consists of
sediment that piles up on the sea floor
Deep Sea Basins
1.
2.
3.
4.
5.
Abyssal plain: flat area
Seamounts: old volcanos and islands
Trenches: deepest part of the ocean
Mid Oceanic Ridge: main feature of the ocean floor
Central Rift Valley: great gap at the center where
plates are pulling apart
Structure of Earth
• Earth Originated 4.5
billion years ago by
the Big Bang
• Earth’s materials
were sorted by
density
– Densest is found at
the center and the
least on the outside
Structure of Earth
• Internal Structure
– Inner Core: composed of Fe Ni,
high pressure and temperatures
reach 5,000oC; solid in nature
– Outer Core: Same elements and
temperature but less pressure so is a
liquid
– Mantle: Contains Si and O, semisolid state that moves like molasses
• Asthenoshere-upper mantle
– Crust: outermost layer, extremely
thin, rigid skin floating on the
mantle (Oceanic and Continental)
• Lithosphere-uppermost mantle
and crust
Earth’s Crust
• Continental Crust
– Consist of granite
– 3.8 byo
– Not dense and thick
•Oceanic Crust
–Consist of Basalt
–200 myo
–Dense and thin
Continental Drift
• Proposed in 1920 by
Alfred Wegener
• Theory: states that all
the continents had
once been joined in a
single super continent
called Pangaea, 180
mya
• Wegener was laughed
at due his inability to
proposed a mechanism
for the movement of
continents
Continental Drift
• Evidence
– Coal deposits
– geological formations
– fossils match up on
opposite sides of the
Atlantic
– Jigsaw puzzle like
appearance of continents
– Glacial rock deposits
– Limestone and salt
deposits
Seafloor Spreading Evidence
• Discovery of the Mid Ocean Ridge
– Discovered using sonar
– Interrupted by large geological fault called
transform faults
– EX: Mid-Atlantic Ridge and East Pacific Rise
Seafloor Spreading Evidence
•
Magnetic Reversals
–
–
–
Discovered by the
Glomar Challenger in
1968
Symmetric Pattern of
Magnetic Bands in the
seafloor from
reversals of the
magnetic poles
Opposite matching
bands on either side of
mid-oceanic ridge
Seafloor Spreading Evidence
•
Sediment Age
and thickness
–
–
Discovered by
the Glomar
Challenger
Thickest and
oldest
sediments are
found farthest
from the Mid
Ocean Ridge
Seafloor Spreading
• Proposed by Henry
Hess in 1960’s
• Theory: states that
mantle rises up at the
Mid Ocean Ridges is
then cooled, placed on
the seafloor and moved
towards the continents
• Mechanism was
thought to be
convection of the
mantle beneath the
seafloor
Plate Tectonics
• Combination of
Continental Drift and
Seafloor Spreading
• Theory: earth’s
surface is covered by a
fairly rigid layer
composed of the crust
and the uppermost part
of the mantle called the
lithosphere that is
broken into plates
which move over the
mantle
Plate Collisions
• Oceanic Plate to Oceanic Plate
– Causes trenches, earthquakes, volcanoes and island
arcs
– EX: Aleutian Island in Alaska
Plate Collisions
•
Oceanic Plate and
Continental Plate
–
–
Creates a trench,
earthquakes,
continental
volcanoes
Seafloor is
destroyed at the
trench which
explains why the
seafloor is so
young
Plate Collisions
•
Continental Plate
and Continental
Plate
–
–
Create mountains
EX: Himalayan
Mountains
Plate Movements
• Apart: plates do move
apart and create new
crust
– EX: mid ocean ridge
and Iceland
• Shear Boundary: plate
are able to slide past
each other
– EX: California’s San
Andreas Fault
Marine Sediments
• Hydrogenous
– Result from chemical reactions within seawater
• Cosmogenous
– Result from outer space
• Lithogenous Sediment
– Formed from the weathering and erosion of rocks
• Biogenous Sediment
– Created from the skeleton or shells of marine organisms
– Calcareous: made of calcium carbonate
– Siliceous: made of silica
Hot Spots
• Stationary plume
of magma under a
moving plate
• Creates volcanic
islands in the
middle of plates
EX: Hawaiian
Islands and the
Emperor
Seamount Chain