TEMPERATURE  The deeper you go, the hotter it gets. & Celsius 4,000° C 4,000 km 2,000 km & kilometers 5,000° C 6,000 km F F mi.

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Published byAmos Stevenson Modified over 6 years ago

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TEMPERATURE The deeper you go, the hotter it gets. & Celsius 4,000° C 4,000 km 2,000 km & kilometers 5,000° C 6,000 km F F mi.

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EARTH’S INTERIOR STRUCTURE Heat flows outward from the interior Crust insulates us from interior heat. Mantle is semi-molten. Outer core is liquid. Inner core is solid.

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3 Major Layers Crust Mantle Core 5 Major Layers Lithosphere Athenosphere Lower Mantle Outer Core Inner Core (Mesosphere)

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COMPOSITIONAL LAYERSPHYSICAL LAYERS (lower mantle)

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EARTH’S INTERIOR STRUCTURE

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Thin outer layer – Continental Crust Lighter (less dense), granitic rock – Oceanic Crust Dense, Basaltic rock Crust thickness varies: up to 70 km in some mountain regions up to 70 km in some mountain regions Less than 5 km in ocean regions Less than 5 km in ocean regions

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The layer below the crust – About 2890 km thick Region of slowly moving convection cells

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Composition – Peridotite a mostly solid basaltic type rock There are 3 regions – based on temperature & plasticity No one has ever drilled to the mantle. It is also very hot

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Center of Earth – Composed of iron-nickel material Under extreme pressure 13x more dense than water CORE

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LITHOSPHERE (Sphere of Rock) Includes Crust & Upper Mantle Crust & uppermost mantle ~ 100 km thick – Continental Crust Lighter (less dense), granite rock – Oceanic Crust Dense, Basalt rock – Upper mantle

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Lithosphere (solid sphere) – Solid brittle rock layer – Includes crust & uppermost mantle Extends to a depth of about 50-100 km

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ASTHENOSPHERE (Weak Sphere) – Upper mantle directly below lithosphere – Extends to a depth of about 100-650 km Hot, plastic rock – Exhibits partial melting – Rock easily deforms (key contribution to Plate Tectonic Theory) Hard rock that acts like warm tar or honey

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Temperature: 900°C to over 4,000 °C (1,652°F – 7,230 °F) – Generate mantle plumes heated by core Heat transferred upward Rest of the mantle Much stronger and hotter than the Asthenosphere 2550 km thick Mesosphere

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2 Distinct Regions Outer Core Inner Core

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Outer Core Liquid layer below Mantle Iron & Nickel composition Temperature – 7200 – 9032 F (4000-5000 C) – Under less pressure than inner core – Allows this region to melt About 2260 km thick generates Earth’s Magnetic Field

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Inner Core Solid Layer beneath the Outer Core Iron & Nickel composition Temperature-9,032 – 10,832 F (5,000-6,000 C) – extreme high pressure – Keeps region solid even though it is the hottest region High density – ≈ 1220 km radius

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Flow of liquid metallic iron in outer core generates magnetic field called the “Magnetosphere” N S North magnetic pole South magnetic pole

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Studies of the path of P & S waves helped to identify the boundaries of Earth’s layers – Determined that the outer core is liquid

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– Seismic waves change direction – As pressure increases w/depth elastic properties of rocks change Slows P-waves by bending them Produces a Shadow Zone because S-waves are not transmitted

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Mohorovicic Discontinuity (Moho) – A boundary that separates the crust from the mantle – Andrija Mohorovicic – 1909, Yugoslavian Seismologist Noticed increase in seismic wave speeds below 50 km of depth

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Moho –Velocity of seismic waves increases abruptly below 50 km of depth –Separates crust from underlying mantle Mohorovicic Discontinuity

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Shadow Zone –Absence of P waves from about 105 degrees to 140 degrees around the globe from an earthquake –Can be explained if Earth contains a core composed of materials unlike the overlying mantle

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Composition of Earth’s layers is determined by: – Studying seismic data – Rock samples from the crust and mantle – Meteorites Assumed to be made up of original Earth forming material – High-pressure experiments on Earth materials Squeezing and heating material under conditions similar to Earth’s deep interior

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Crust –Early seismic data and drilling technology continental crust – mostly light, granitic rocks Ocean crust – dark, dense, basaltic rocks Mantle – Composition is less certain o Some lava that reaches surface comes from the asthenosphere Core – Thought to be mainly dense iron and nickel o similar to metallic meteorites o surrounding mantle believed to be composed of rocks similar to stony meteorites

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