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Plate Tectonics
Activity 1
In activity 1 I learned that the crust
is the thin outermost layer of the Earth
while the continental crust is 30-50 km
thick and is pretty old and the oceanic
crust is 5-10 km thick and is young and
new.
The lithosphere is the outermost
layer of the earth, it consists the Earth’s
crust and part of the upper mantle.
Asthenosphere is the part of the
mantle beneath the lithosphere. The
asthenosphere undergoes slow flow while
the lithosphere behaves as a rigid block.
Mid-Ocean ridges is a chain undersea
ridges extending throughout all of the
Earth’s ocean basins, and formed by sea
floor spreading. Volcanic rocks are taken
from the ocean floor because it shows the
age of the rock increases from the crest of
the ridge.
Continued….
The global positioning system
is a satellite-based system for accurate
locations of points on the Earth. The
GPS consists of 24 satellites that orbit
the Earth at a height of 20,000 km. All
magnets and materials that have
magnesium have a North and South
direction, or magnets polarity.
The picture next to me is called
basalt it is a kind of volcanic igneous
rock that has a high content of iron and
it is usually a dark color.
The mantle is the zone of the
Earth, below the crust and above the
core, it is divided into the upper mantle
and the lower mantle.
Activity 2
The image next to me is called a
divergent boundary it is when two plates
move away from each other, mid-ocean
ridges is an example of a divergent
boundary, it is when the asthenosphere
rises slowly upward and the magma rises
up because it is less dense then the rock
and it forms volcanoes in the central
valley of the mid-ocean ridge. Some of the
magma stays below the sea floor and
crystallizes into rock there. The rocks then
at the sea floor makes a new oceanic crust.
New Ocean forms when hot mantle
material begins to move upward beneath a
continent. The lithosphere of the continent
bulges upward and is stretched sideways,
eventually it breaks along a crack.
The Atlantic ocean is getting wider
because new lithosphere is being created
at the mid-ocean ridge but it is not being
consumed in the edges of the continent.
Continued….
The image next to me is a
convergent boundary which is where two
plates wove toward each other. To make a
subduction you have to make one plate
move downward into the mantle beneath the
edge of the other plate at a convergent plate
boundary. The down going plate is the
oceanic lithosphere, the plate that stays at
the surface can either be the oceanic
lithosphere or the continental lithosphere.
To create a volcanic island arc is by
the mantle asthenosphere magma is
produced at a certain depth. The magma
rises up to the ocean floor to form a chain of
volcanic islands.
A suture zone is the zone of the
earth’s surface where two continents have
collided and have been welded together to
form a single continent.
Continued….
The last kind of boundary is a
transform plate boundary which is
where two plates slide parallel to each
other. A transform fault is a vertical
surface of slippage between two
lithospheric plates along an offset
between two segments of a spreading
ridge.
The movement along transform
vault forms is limited to the distance
between the two segments of ridge
crest.
Activity 3
In this activity, I learned about density which is the mass per unit volume of a material
or substance and that less dense material tends to rise upward and float on more dense
material. Rocks deep in the earth are more dense than the same rocks when they are at
surface. The weight of overlying rocks put pressure on the rocks below making it more dense.
Earthquake waves that travel at 4.9 km/s at the surface, and travels 6.4 km/s at a depth of
1600 km. Temperature affects the density of materials. As rocks in the interior of the earth are
heated enough, their density decreases.
The core is the solid, innermost part of the earth consisting mainly of iron. The core is
so hot that the outer core is molten. The inner core is also hot but under such great pressure
that it remains solid.
Thermal convection is a pattern of movement in a fluid caused by heating from below
and cooling from above. Thermal convection transfers heat energy from the bottom of the
convection cell to the top. Rising mantle can break a continent apart and then force the two
parts of the broken continent in opposite directions. The continent would then be carried out
by the convention currents. Most dense material is at the center of the earth.
Activity 4
In this activity I learned about
plate tectonics which is the field of study
of plate motion, plate tectonics create
mountain ranges, trenches, and rift
valleys at or near plate boundaries.
Oceanic trenches happens when an
oceanic plate is subducted under another
plate, it bends downward as it enters the
subduction zone. The valley that is
formed about the zone of bending is
called a trench. Trenches are common to
the western pacific, where there is
ocean-ocean subduction. For an
example, there is a long trench along the
west coast of South America where the
Nazca plate is being subducted under the
continent.
Continued….
Volcanoes are common along
mid- ocean ridges where basalt magma
rises up from the asthenosphere to
form new oceanic crust. Volcanoes are
common along subduction zones
where they form volcanic arcs.
When the oceanic crust is first
produced at the mid-ocean ridges, a lot
of water is combined with certain
minerals in the igneous rocks. As the
pressure and temperature increases
down the subduction zone, this water
is driven off, and it rises upward from
the plate. The melting temperature of
the mantle rock above the plate is
toward when water is added to it. This
causes some of the mantle rock to
melt.
Continued…
Earthquakes are along mid-ocean
ridges are common because of movement
along the transform faults that connect
segments of the ridge crest. In subduction
zones it happens at depths that are very
shallow or near the trench.
Hot spots originate the boundary
between the mantle and the outer core,
they are narrow plumes of unusually hot
mantle material. Continental accretion is
the growth of a continent along it’s edges.
Continents grow as the igneous rocks of
volcanoes and batholiths are added to the
continent above the subduction zone.
When two plates are pushed
together by plate movements elsewhere,
great masses of rock are pushed together
and stacked on top of one another in
complicated structures, to form high
mountains.
Activity 5
In activity 5, in the late 1800s study the discovers of similar fossils on continents that
are now separated widely by oceans. Edward Suess is an 1800 Austrian geologists that came
up with the contraction theory. Suess stated that as the earth cooled from a molten state, the
more dense materials contracted and sank toward the center, and the least dense materials
“floated” and cooled to form the crust. Suess claimed that certain parts of the seafloor and
continents could rise and sink as they adjusted to changes in the cooling earth. So Suess
started to create land bridges thinking that it would allow various animals and plants to
migrate and spread without crossing an ocean.
Pangea is the earth’s most recent super continent which was rifted apart about 200
million years ago. Pangea started to break up because the continental rifts began to form, as
pangea continued to be rifted apart, oceanic crust formed between the Northern continents and
the Southern continents. A supercontinent is a large continent consisting of all of the Earth’s
continental lithosphere. Supercontinents are assembled by plate tectonic processes of
subduction and continent-continent collision. A paleomagnetism is the record of the past
orientation and polarity of the earth’s magnetic field recorded in rocks containing the material
magnetite. Rock types and fossils provide evidence for the locations of ancient seas, glaciers,
mountains and ecological regions.
Continued….
Alfred Wegener is a 1912 German
geologists proposed the hypothesis of
continental drift, according to Wegener,
Pangea broke into separate continents that
moved apart. Wegener claimed that
compressions at the leading edge of the
moving continent. Wegener’s hypothesis
allowed him to explain that the different
ages of the different mountain belts. He
claimed that the timing of the break up
was variable, with some parts of Pangea
separating earlier than others. Wegner’s
thought that the material beneath the
earth’s lithosphere acts like a slow moving
fluid. Some scientists agree with Wegener
while others argue that it would be
impossible for continents to “plow
through” the ocean floor.
The End!!!!