Plate Tectonics and Continental Drift Continental Drift What

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Plate Tectonics and Continental Drift

Plate Tectonics and Continental Drift

Continental Drift What is continental drift? The theory of continental drift states that Earth’s

Continental Drift What is continental drift? The theory of continental drift states that Earth’s continents were once joined in a single large landmass that broke apart, and that the continents have drifted to their current locations.

Continental Drift Where this idea come from? The theory was proposed by The German

Continental Drift Where this idea come from? The theory was proposed by The German scientist Alfred Wegener in 1912

Continental Drift Is this theory true/reasonable? v. Geologists have found a lot of evidence

Continental Drift Is this theory true/reasonable? v. Geologists have found a lot of evidence to support this theory

Continental Drift Give some evidence that can support this theory v. Rocks v. Fossils

Continental Drift Give some evidence that can support this theory v. Rocks v. Fossils v. Measurements v. Ocean-floor structures

Plate Tectonics How is the idea of plate tectonics different from the idea of

Plate Tectonics How is the idea of plate tectonics different from the idea of continental drift? v. Today’s theory of plate tectonics is a more complete picture that includes all the evidence

Plate Tectonics What causes the plate tectonics to move? v. A convection current Ø

Plate Tectonics What causes the plate tectonics to move? v. A convection current Ø Uneven heating causes material in the mantle to constantly and slowly rise and fall.

Plates Boundaries There are three types of boundary depending on how they are formed

Plates Boundaries There are three types of boundary depending on how they are formed v. Convergent boundary v. Divergent boundary v. Transform boundary

Plates Boundaries There are seven major lithospheric plates v. Pacific v. North American v.

Plates Boundaries There are seven major lithospheric plates v. Pacific v. North American v. South American v. Eurasian v. African v. Indo-Australian v. Antarctic

Plates Boundaries Ø Plate boundaries occur where the edges of plates meet Ø The

Plates Boundaries Ø Plate boundaries occur where the edges of plates meet Ø The type of boundary depends on whether the plate forming them are moving toward each other, separating, or sliding past each other.

A Convergent Boundary Ø It forms where plates collide. Ø The pressure and violence

A Convergent Boundary Ø It forms where plates collide. Ø The pressure and violence at convergent boundaries produces mountains and bands of earthquake and volcanic activity.

A Convergent Boundary Ø When continental plates collide, there is uplift and mountains are

A Convergent Boundary Ø When continental plates collide, there is uplift and mountains are made Ø When ocean plate collide with continental plate, there might be uplift or subduction

A Convergent Boundary Ø What is subduction? v. It is the movement of one

A Convergent Boundary Ø What is subduction? v. It is the movement of one plate under another. v. It happens at converging plate boundaries v. It causes eruption of volcano

A Transform Boundary Ø It forms where two plates slide past each other. Ø

A Transform Boundary Ø It forms where two plates slide past each other. Ø The sliding causes rocks along the boundary to grind against each other from time to time, causing jolts that we feel as earthquakes

A divergent Boundary Ø It forms when two plates diverge or move away from

A divergent Boundary Ø It forms when two plates diverge or move away from each other. Ø Most of divergent boundaries are in the oceans v. Mid-ocean ridge

Earthquakes ØIn Earth’s crust, movements occurs along faults. ØFaults are large cracks in Earth’s

Earthquakes ØIn Earth’s crust, movements occurs along faults. ØFaults are large cracks in Earth’s crust

Earthquakes… Ø How do Earthquakes occur? üToo much pressure forces rocks on either side

Earthquakes… Ø How do Earthquakes occur? üToo much pressure forces rocks on either side of a fault to past each other and release the pressure.

Earthquakes… Ø The place in the Earth’s crust where the pressure is released is

Earthquakes… Ø The place in the Earth’s crust where the pressure is released is called focus. Ø The focus can be many kilometers down in the crust

Earthquakes… Ø What is an Earthquake epicenter? üIt is the spot on Earth surface

Earthquakes… Ø What is an Earthquake epicenter? üIt is the spot on Earth surface directly above the focus.

Earthquakes… Ø Do Earthquakes produce waves? üYes, earthquakes waves are known as seismic waves

Earthquakes… Ø Do Earthquakes produce waves? üYes, earthquakes waves are known as seismic waves üEarthquakes make three kinds of seismic waves

Seismic waves They are vibrations generated by the Earth’s interior that carry energy away

Seismic waves They are vibrations generated by the Earth’s interior that carry energy away from the focus toward the surface of the Earth where we experience them as Earthquakes.

Earthquakes… Ø What are the kinds of Earthquake waves? üPrimary waves (body) üSecondary waves(body)

Earthquakes… Ø What are the kinds of Earthquake waves? üPrimary waves (body) üSecondary waves(body) üLand waves(surface)

Primary waves Ø Also called P-waves Ø They stretch and compress land as they

Primary waves Ø Also called P-waves Ø They stretch and compress land as they pass through Ø They are compressional waves Ø They can travel through liquid and solid Ø They are fast

Primary waves

Primary waves

Secondary waves Ø Also known as S-waves Ø They move land side by side

Secondary waves Ø Also known as S-waves Ø They move land side by side Ø The are shearing waves Ø They can only travel through a solid Ø They are slow

Secondary waves

Secondary waves

Land waves Ø Also Known as surface waves or L-waves Ø They form when

Land waves Ø Also Known as surface waves or L-waves Ø They form when P- and Swaves combine Ø They can move land up and down

Land waves

Land waves