Plate Tectonics

How is trench suction different from ridge push and slab pull?

It is not a result of gravity.

Describe what happens in ridge push.

In ridge push, the mantle well upward because of convection and elevates the edges of spreading oceanic plates. These plate are higher at the spreading center. As a result, gravity forces the plates downhill, and they eventually flatten out to the ocean floor. Gravity give the plates a push along as new crust forms behind the plate at the spreading center.

What is the largest major tectonic plate?

Pacific Plate

What are the three type of plate boundaries?

divergent, convergent, transform

What part of Earth's interior do tectonic plates "float" on?

asthenosphere

Which type of plate boundary is formed by two tectonic plates sliding past each other as the move in opposite directions?

transform boundary

Which major plate includes Africa and the surround oceanic crust?

African Plate

Give an example of a rift valley.

African Rift Valley in East Africa

Which type of plate boundary is where two separate places are pushing into one another?

convergent

Which type of plate boundary is a fault where two plates are moving away from each other?

divergent

How an the boundaries of slab pull be identified?

by deep ocean trenches

What theory hypothesized that new oceanic crust is constantly being formed due to the upwelling of magma through diverging tectonic plates?

seafloor spreading

How many major tectonic plates are there?

7

What is a rift valley?

A deep valley that forms where two plates move apart

Define supercontinent.

A supercontinent is a giant landmass made up of many or all continents.

How was Wegener's theory of continental drift proven after his death?

After WWII, countries began mapping the ocean floor. As the did, they discovered underwater mountain ranges and the separation of the ocean floor at giant cracks.

Identify Albert Wegener and describe his continental drift theory.

Alfred Wegener was a German meteorologist who began looking for evidence to support the idea that continents move around on the Earth's surface. His theory, known as continental drift, proposes that the continents were connected at one time in Earth's history and have drifted to their present location. This theory also states that the continents are still moving today. In 1915, he published his theory in his book, The Origin of Continents and Oceans.

Explain the development of an ocean trench.

An ocean trench forms a line of two colliding tectonic plates. One plate made of oceanic crust can slide underneath another plate forming a narrow, deep trench. This happens because oceanic crust is more dense than continental crust, making it more likely to be pushed back into the mantle.

What major tectonic plate includes the continent of Antarctica and the surround oceanic crust?

Antarctic plate

Describe how convergent boundaries can form volcanic mountains and islands.

As one plate is being forced under another, it begins to melt, and a line of volcanoes form parallel to a trench. If one plate is oceanic crust, the line of volcanoes will become islands. If it is continental crust, the line will become volcanic mountains.

Describe slab pull.

As the plate is pushed along, it may run into another plate. Oceanic crust is forced under another plate and back into the mantle. As this happens, gravity works to pull it along, giving the plate another force to keep it moving.

Define drifting.

Drifting refers to the act of the continents slowly breaking apart.

What effect can happen at a transform boundary?

Earthquakes are the only effects at a transform boundary.

Which major tectonic plate includes most of Europe and Asia and nearby oceanic crust?

Eurasian plate

How did evidence collected from the DSDP support the theories of seafloor spreading and plate tectonics?

Evidence collected from the Mid-Atlantic Range showed two important thing. First, rocks found near the ridge were very young, and they got older farther away from the crest. Second, the samples showed that layers of sediment were thinner at the crest and thickened farther away from that area. These conclusions proved that new oceanic crust was being formed along the plate boundary and spreading out laterally; thus, supporting the theory of seafloor spreading and plate tectonics.

Describe ridge push.

In ridge push, plates that are higher at the spreading center flow downhill and flatten out to the ocean floor, which is caused by gravity. Gravity may give the plate a slight push along as the new crust is forced up at the fault, causing the rest to move out of the way. As the plate is pushed along, it may run into another plate. Oceanic crust is forced under another plate and back into the mantle. These boundaries can be identified by deep ocean trenches that mark the location where one plate is sliding under another one. As it slides under the other plate and is forced back into the mantle, gravity works to pull it along, giving the plate another force to keep moving.

How is slab pull different from ridge push?

In slab pull, gravity is pulling the front part of the plate; in ridge push, it is forcing movement from the back end.

Describe the Deep Sea Drilling Project (DSDP) and the Glomar Challenger.

In the 1960s, the Deep Sea Drilling Project (DSDP) was designed to analyze the ocean floor. The Glomar Challenger was the research vessel equipped with a drilling platform that extracted samples from the ocean floor.

What major tectonic plate includes the India subcontinent, Australia, and surrounding oceanic crust?

Indo-Australian plate

Explain what the main cause of plate movement.

It is theorized that the plates move around on top of the mantle due to convection currents caused by heat from the earth's core. Rock near the mantle is heated and rises toward the crust. The rock near the surface is cooler and sinks back down toward the core. These convectin currents encounter the thin crust, causing it to move. The plates collide into each other, slide past one another, or are pushed under another plate. Scientists believe this cycle takes thousands of year.

Describe what may occur at a divergent boundary.

Many things may occur at a divergent boundary. Volcanic activity is common since mantle can easily move to the surface through the thin, fractured rock as plates separate. If a continent is the place where a divergent boundary occurs, then the continent will begin to be torn apart as the sides of the plate separates, creating a rift valley.

What ocean ridge runs up through the northern Atlantic Ocean where it separates the North American plate from the Eurasian plate?

Mid-Atlantic Ridge

What sorts of tectonic activity may happen when two tectonic plates meet?

Mountain building, earthquakes, tremors, or volvanoes.

What major tectonic plate extends from the middle of the Atlantic ocean to the West Cost of North America?

North American Plate

Identify the major tectonic plates.

North American Plate South American Plate Pacific Plate African Plate Eurasian Plate Indo-Australian Plate Antartic Plate

What is the only major tectonic plate located mainly underwater?

Pacific Plate

Which plate lies beneath the Pacific Ocean?

Pacific Plate

Describe plate tectonics.

Plate tectonics is the push together, pulling apart, or sliding past each of tectonic plates.

Describe how an earthquake can occur at a transform boundary.

Pressure for the plates to move builds over time. The rocks compress and strain. The stored energy is released as the plates move, which can be several feet at one time. The result is an earthquake.

Describe Laurasia.

Scientists believed that one of the first splits of Pangea created a Northern part and Southern part. The Northern part was name Laurasia and contained the continents of North America, Europe, and Asia.

Describe Gondwana.

Scientists believed that one of the first splits of Pangea created a Northern part and Southern part. The Southern part was named Gondwana and contained the continents of South America, Africa, India, Australia, and Antartica.

How are the major tectonic plates named?

Six of the 7 major tectonic plates are names for the continents or landmasses they contain, with the exception of the Pacific plate.

Explain why some scientists consider the continents of Europe and Asia a supercontinent.

Some scientists consider Europe and Asia a supercontinent because they currently exist as one landmass and are only separated by the Ural Mountains, which were formed by the two landmasses colliding.

What major tectonic plate extends from the middle of the Atlantic Ocean to the west coast of South America?

South American Plate

What two plates meet at the Mid-Atlantic Ridge that allow magma to seep through the ocean floor, producing new layers of oceanic crust?

South American Plate and the African Plate

Describe tectonic plates.

Tectonic plates are pieces of the crust that move around on the earth.

What happens when tectonic plates meet?

The area where they meet becomes a site for tectonic activity.

Define asthenosphere.

The asthenosphere is the upper part of the mantle.

Define core.

The core is the center of the earth. It consists of two parts - a solid center (inner core) and a liquid layer of iron and nickel (outer core).

Identify and describe the force that causes the most plate movement.

The force that causes the most plate movement is thermal convection. In thermal convection, heat from Earth's core causes currents of hot rising magma and cooler sinking magma to flow. These currents push the plates along according to the direction of the flow. At the top of Earth's mantle, the rock encounters the thin crust, and, as it is pushes aside, lava flows out from the mantle to form new oceanic crust. The plates smash into each other, slide past each other, or are pushed under another plate. This movement, along with the upwelling of the mantle by the convection currents, may also cause secondary actions to assist in plate movement.

Define lithosphere.

The lithosphere is the hard outer layer of the earth.

Define mantle.

The mantle is the middle layer of earth, consisting of mostly oxygen, silicon, magnesium, and iron.

How is plate tectonics observed?

The movement of tectonic plates can be observed and measured using GPS systems. The edges of the plates can be detected as their edges can be seen.

Describe trench suction.

The plate being forced back into the mantle is doing so at an angle. Underneath and behind the plate, a small convection current caused by the diving crust can form and help pull the plate into the Earth. This current aids in pulling the plate back into the interior to re-melt.

What will happen if both plates are made of continental crust at a convergent boundary?

The plates will crumple up forming high mountain range.

What actions determine what kind of tectonic activity could happen when two tectonic plates meet?

This depends on whether they are moving toward each other, sliding past one another, or pulling apart.

If new crust is being made, why is the earth not getting any larger?

This is because the old crust is being pushed into the earth's interior and being re-melted at the same rate new crust is formed.

Describe the plate tectonics theory.

This is the theory that the surface of the earth is broken into larger pieces of crust called plates that ride along on the asthenosphere, which is the upper part of the mantle

Describe the evidence Wegener found to support his theory.

Wegener discovered many scientific papers that described data that did not seem to fit to the accepted model of stationary continents. He learned that geologists noticed rocks of similar type and formation existed in Canada and in Scandinavia, as well as other locations. He discovered other geologists found fossils of the same plants and animals on widely separated continents, sometimes in locations where they never could have existed, such as tropical plants in Antartica.

Explain why Wegener proposed the name "Pangea" for the name of the supercontinent.

Wegener proposed Pangea because Pangea mean 'whole earth.'

What term refers to the outermost shell of the earth that is made up of the earth's crust and the upper part of the mantle?

lithosphere

What other term refers to tectonic plates?

lithospheric plates

What two surface feature are associated with convergent boundaries?

ocean trench and volcanic mountains or islands

What term refers to the theory that Earth's crust is broken up into plates?

plate tectonics

What are the secondary mechanisms that assist in plate movement?

ridge push, slab pull, and trench suction

What are the plate-like sections o Earth's crust referred to as?

tectonic plates

Give an example of volcanic mountains formed by a convergent boundary.

the Cascade Range or the Andes Mountains

Give an example of a high mountain range formed at a convergent boundary.

the Himalayas

What underwater mountain range runs from Iceland to Antarctica?

the Mid-Atlantic Range

Give an example of an island formed by a convergent boundary.

the Phillipines

What is the most famous example of a transform boundary?

the San Andreas Fault in California