earth's crust, a steno sphere, litosphere

8/2/2019 Earth's Crust, A Steno Sphere, Litosphere

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ar qua es,Volcanoes,

Mountain Ranges,Mid-oceanicRidges, and

Tectonic Plates



Why do we have plate

Tectonics?Plate Tectonics and all of the exciting geologyassociated with it, is the result of Earth’s attempt to

cool down.

It is the result of the second law of Thermodynamics,which implies that heat tends to flow from hotterregions to cooler regions.



Planets cool down by a combination of radiation,conduction and convection. Once the heat gets out

of Earth’s surface, it radiates out into space, but itgets to the surface by conduction and convection.

A tectonic plate (also called lithospheric

plate) is a massive, irregularly shaped slab of solidrock, generally composed of both continental andoceanic lithosphere.



Plate size can vary greatly, from a few hundred tothousands of kilometers across; the Pacific andAntarctic Plates are among the largest.

Plate thickness also varies greatly, ranging from lessthan 15 km for young oceanic lithosphere to about200 km or more for ancient continental lithosphere

(for example, the interior parts of North and SouthAmerica).



Earthquake

is the vibration of Earth produced by the rapid releaseof energy. Earthquakes are often caused by slippagealong a break in Earth’s crust.

An earthquake is what happens when two blocks ofthe earth suddenly slip past one another. Thesurface where they slip is called the fault or fault

plane . The location below the earth’s surface wherethe earthquake starts is called the hypocenter , andthe location directly above it on the surface of theearth is called the epicenter .



A Volcano

is a place on the Earth's surface (or any otherplanet's or moon's surface) where molten rock,gases and pyroclastic debris erupt through the

earth's crust.

Volcanoes vary quite a bit in their structure - someare cracks in the earth's crust where lava erupts, andsome are domes, shields, or mountain-like structureswith a crater at the summit.



A Mountain Range

is a group or chain of mountains that are closetogether. Mountain ranges are usually separatedfrom other mountain ranges by passes and rivers.



The Mid-Ocean Ridge

is an interconnectedsystem of underseavolcanoes that meander

over the Earth like theraised seams on abaseball. It is acontinuous 40,000-mile(60,000-kilometer)

seam that encirclesEarth and bisects itsoceans.



Describe the relationships

among earthquakes,

volcanoes, mountain ranges,mid-oceanic ridges, and

tectonic plates.



Earth's Crust,Astenosphere,

Litosphere



Th E th' C t



The Earth's Crust,

Lithosphere and

Asthenosphere

Crust, the upper layer of the Earth, is not always thesame.

Crust under the oceans is only about 5 km thickwhile continental crust can be up to 65 km thick.

Also, ocean crust is made of denser minerals thancontinental crust.

http://www.windows2universe.org/earth/Interior_Structure/interior.html

http://www.windows2universe.org/earth/Interior_Structure/interior.html



Inner Core – 1200 km made of solid Fe, Ni.

Outer Core – 2250 km made of liquid Fe, Ni.

Mantle – 2900 km made of dense rocks.Crust – 5 – 40 km made of solid lighter rocks.

Lithosphere (Crust and MOHO) – 100km thick.

MOHO = Mohorovicic Discontinuity



The tectonic plates are made up of Earth’s crust and

the upper part of the mantle layer underneath.Together the crust and upper mantle are calledthe lithosphere and they extend about 80 km deep.

The lithosphere is broken into giant plates that fitaround the globe like puzzle pieces. These puzzlepieces move a little bit each year as they slide ontop of a somewhat fluid part of the mantle called theasthenosphere. All this moving rock cancause earthquakes.

http://www.windows2universe.org/earth/interior/plate_tectonics.html

http://www.windows2universe.org/earth/geology/quake_1.html

http://www.windows2universe.org/earth/geology/quake_1.html

http://www.windows2universe.org/earth/interior/plate_tectonics.html



The asthenosphere is ductile and can be pushedand deformed like silly putty in response to thewarmth of the Earth.

These rocks actually flow, moving in response to thestresses placed upon them by the churning motionsof the deep interior of the Earth. The flowingasthenosphere carries the lithosphere of the Earth,including the continents, on its back.



Litosphere

The solid, rocky crust coveringentire planet. This crust is

inorganic and is composed ofminerals.It covers the entire surface of the earth fromthe top of Mount Everest (the world's highest peak that

is part of the Himalaya mountain range along the border of Nepal andTibet) to the bottom of the Mariana Trench (the

deepest part of the world's oceans. It is located in the western Pacific

Ocean, to the east of the Mariana Islands).



The lithosphere is the outer solid part of the earth,

including the crust and uppermost mantle. Thelithosphere is about 100 km thick, although itsthickness is age dependent (older lithosphere isthicker).

The lithosphere below the crust is brittle enough atsome locations to produce earthquakes by faulting,such as within a subducted oceanic plate.

earth's crust, a steno sphere, litosphere

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