Plate Tectonics

Activity 1In 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 2The 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!!!!