Chapter 5 Plate Tectonics Section 5 Plate Tectonics

What do scientistis think causes the movement of Earth's plates?

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fault

A break in Earth's crust where rocks have slipped past each other.

Divergent Boundary

A rift balley forms when two pieces of continetal crust pull apart.

What are plates?

A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.

plate

A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.

Describe the type of movement that occurs at each type of plate boundary.

Divergent - move apart - MOR (Iceland) Convergent- move together - Mountain rangers, contiental and island arcs, trenches (Pero-Chili trench) Transform- move past each other - San Andreas fault , > At a divergent boundary two of Earths plates slide apart. At a converging boundary is when two plates come together and converge. At a transform boundary two plates slip past each other moving in opposite directions.

How can Earth'splates move? What force is great enought to move the heavy continents?

Geologists think that movement ofconvection currents in the mantle is the major force taht causes plate motion. Suring subduction, gravity pulls one edge of a plate down into the mantle. The rest of theplate also moves This slow movement is similar to what happens in a pot of soup when gravity causes the cooler, denser soup near the surface to sink.

When two plates carrying continental crust collide subduction does not take place.

Neither piece of crust is dense enought to sink very far into the mantle. Instead the collision squeeses the crust into mighty mountain ranges.

What is likely to occur at a plate boundary where oceanic crust collides with continetal crust?

Oceanic crust is more dense than continental crust. The less dense continental crust can't sink under the more dense oceanic crust. Instead, subduction occurs as the oceanic plate sinks beneath the continental plate.

Sometimes a plate carrying oceanic crust collides with a plate carrying continental crust.

Oceanic crust is more dense than continental crust. The less dense continetal crust can't sink under the more dense oceanic crust. Instead, subducton occurs as the oceanic plate sinks eneath the continental plate.

Divergent Boundary

Sea-floor spreading occurs as oceanic plates move apart along the mid-ocean ridge.

What is the theory of plate tectonics?

The Earth's crust is divided into huge plates that move and interact with each other due to convection currents in the mantle The theory of plate tectonics explains the formation, movement, and subduction of Earth's plates.

divergent boundary

The place where two plates move apart, or diverge is called a ____________________________________.

What is the theory of plate tectonics?

The theory of plate tectonics explains the formation, movement, and subduction of Earth's plates.

plate tectonics

The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle.

as plates move, they collide, pull apart, or grind past each other, producing spectacular changes in Earth's surface.

These changes include volcanoes, mountain ranges, and deep ocean trenches.

Convergent Boundary

Two continental plates collide forming a mountain range.

Transform Boundary

Two plates slide past each other.

Convergent Boundary

When two plates of oceanic crust collide, one plate is subducted beneath the other.

Rift valley

a deep valley that forms where two plates move apart. example: the Great Rift Valley in East Africa marks a deep crack in the African continent.

transform boundary

a place where two plates slip past each other, moving in opposite directions.

scientific theory

a well-tested concept that explains a wide range of observations

Oceanic crust becomes cooler and denser

as it spteads away from the mid-ocean ridge.

When two plates converge, the result is called a

collision.

What are the three types of plate boundaries?

divergent boundaries, convergent boundaries, and transform boundaries

What are the three types of plate boundaries?

divergent boundaries, convergent boundaries, and transform boundaries. A different type of plate movement occurs along each.

Plate boundaries

divide the lithosphere into large plates

transform boundary

is a place where two plates slip past each other, moving in opposite directions. Earthquakes often occur along _________________, vut crust is neither created nor destroyed.

Earth's lithosphere is broken into plates

like the cracked shell of a hard boiled egg.

Plate movements have built

many of the features of Earth's land surfaces and ocean floors.

What features from where two continental plates come together?

mighty mountain ranges

When two plates collide,

the density of the plates determines which one comes out on top.

The theory of plate tectonics explains

the formation, movement, and subduction of Earth's plates.

convergent boundaries

the place where two plates come together, or converge is called a ____________________________.

Where two plates carrying oceanic crust meet at a trench,

the plate that is more dense sinks under the other plate.