(3) Earths Interior

Draw the interior of the earth.

Crust

Solid rock (basalt & granite). Thin, outermost layer of rock.

Mantle

Solid rock (periodotite). Thick, middle zone. Composed of solid rock but can flow.

Core

Central zone on Earth that consists of two parts. Liquid iron outer core and a solid iron inner core.

Oceanic Crust

Thinner (<8 km), denser, mafic (basalt).

Continental Crust

Thicker (<70 km), less dense, felsic (granite). Continental crust contains older rocks than oceanic crust.

Outer Core

Liquid iron and nicken (30.8% of Earth’s mass). Generates Earth’s magnetic field.

Inner Core

Solid iron and nickel (1.7% of Earth’s mass).

Lithosphere

Rigid outer layer including the crust and uppermost mantle.

Asthenosphere

Weaker, ductile layer of the upper mantle beneath the lithosphere, allowing for plate movement.

Mesosphere

The remaining part of the mantle below the asthenopehere.

Geothermal Gradient

Temperature increases with depth. Averages about 25 degrees C per km, but varies geographically.

Geopressure Gradient

Pressure increases with depth at a relatively constant rate everywhere.

Lithostatic Pressure

Confining pressure occuring equally in all directions.

Directed Pressure

Pressure applied in a particular direction (e.g., from plate tectonics).

Isostacy

The equilibrium of adjacent blocks of lithosphere “floating” on the asthenosphere. Less dense lithosphere floats higher.

Isostatic Adjustment

Vertical movement of the lithosphere to achieve equilibrium (e.g., mountains rising as they erode).

Glacial Isostacy

Crust is depressed by the weight of glaciers and rebounds after ice melts.

Hydroisostacy

Crust is loaded by water during sea-level rise.

Mantle Convection

Circulation of warm, less dense material rising and cooler, denser material sinking. Drives plate tectonics.

Magma Formation

Magma is generayed by decompression melting, flux melting, and partial melting.

Decompression Melting

Hot rock rises, reducing pressure and lowering its meling point. Occurs at divergent plate boundaries.

Flux Melting

Water or other volatiles are introduced, lowing the melting point of rocks. Occurs at subduction zones (convergent plate boundaries).

Partial Melting

As temperature increases, minerals with lower melting points melt first.

Earth’s Magnetic Field (Geodynamo)

Generated by the convection of liquid iron in the outer core. This field protects Earth from solar wind. The magnetic poles wander over time, and the field can reverse polarity.