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Plate Tectonics. Structure of Earth (16a). The Earth is divided into 3 main layers As you travel deeper through the layers of the Earth, the: Temperature Increases Pressure Increases Density Increases. Structure of Earth (16a). Crust – The outermost layer of the Earth.
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Structure of Earth (16a) • The Earth is divided into 3 main layers • As you travel deeper through the layers of the Earth, the: • Temperature Increases • Pressure Increases • Density Increases
Structure of Earth (16a) • Crust – The outermost layer of the Earth. It is between 5 to 100 km thick. It is the thinnest layer of the Earth. There are two types of crust. Oceanic crust – thinner, more dense, mostly made of basalt Continental crust – thicker, less dense, mostly made of granite Temperatures range between 0 to 1000ᵒ C
Structure of Earth (16a) • Mantle – The layer of the Earth between the crust and the core. It is thicker than the crust. It contains most of the Earth’s mass. It is 2,900 km thick. Temperatures range between 1,000 to 3,700ᵒ C.
Structure of Earth (16a) • Core - The layer of the Earth that extends from below the mantle to the center of the Earth. It is divided into 2 layers: inner core and outer core. It is made mostly of iron and nickel. It has a radius of 3,430 km Temperatures can range from 3,700 to 7,000ᵒ C.
Physical Layers (16a) • The Earth is divided into five physical layers • Lithosphere - Rigid, outermost layer • Asthenosphere - “Plastic like” layer of the upper mantle where the tectonic plates float • Mesosphere - Strong lower part of mantle • Outer Core - Liquid layer below the mantle • Inner Core - Solid dense layer
Plate Tectonics (17b) • Tectonic Plates – Pieces of the lithosphere (crust) that move around on top of the asthenosphere. • Convection Currents in the mantle are what causes the tectonic plates to move. • Scientist study seismic waves to learn more about the Earth’s interior.
Continental Drift (17b) • Continental Drift – The theory that states that the continents once formed a single landmass, broke up, and drifted to their present locations. • Three pieces of evidence that support this theory are the coastlines of continents fit together , fossil evidence such as Mesosaurus (animal) and Glossopteris (plant) , and evidence from climate change
Continental Drift (17b) • Alfred Wegener – The scientist who developed the theory of Continental Drift • Most people did not believe his theory because he could not explain what force made the continents move. • Pangaea– The single landmass that existed 245 million years ago.
Continental Drift (17b2) • Sea Floor Spreading - the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies • This occurs at the Mid-Ocean Ridge • Mid-Ocean Ridge - underwater mountain chains that run through Earth’s ocean basins • The Mid-Ocean was mapped using sonar by Harry Hess.
Plate Boundaries (17a) • Convection Currents in the mantle are what causes the tectonic plates to move. • A boundary is where tectonic plates touch • There are 3 types of boundaries Convergent – move toward each other Divergent – move away from each other Transform – slide past each other
Deformation (17a) • Deformation - The process by which the shape of a rock changes because of stress by bending or breaking. • 3 different types of stress: Compression- when an object is squeezed at a convergent boundary. Tension - when forces act to stretch an object at a divergent boundary. Shearing – when forces slide past each other at a transform boundary.
Deformation (17a) • Folding- The bending of rock layers because of stress in the Earth’s crust.
Faults (17a) • Fault - The surface along which rocks break and slide past each other. • There are two sides of a fault: Hanging Wall and Footwall
Faults (17a) • There are 3 types of faults: Normal Fault – Form where rocks are pulled apart because of tension at divergent boundaries. Reverse Fault – Form where rocks are pushed together by compression at convergent boundaries. Strike-Slip Fault – Form where rocks slide past each other horizontally by opposing forces at transform boundaries.
