ES 5: Layers, rocks

Inner Core

-Discovered by Inge Lehmann in 1936

-Radius of 1250 km

-Solid Fe-Ni alloy

-Magnetic

-approximately 6000ºC

-3.6 million atm

Outer Core

-Discovered by Richard Dixon Oldham (earth’s core as a whole) in 1906.

-2300 km thick

-Liquid Fe and Ni

-Magnetic

-4000-5000ºC

Lehmann discontinuity

Boundary between the inner and outer core.

Mantle

-average thickness is ~2900 km.

-84% of the earth’s volume.

-Predominantly made of Silicate rock

-Subdivided into the 2 parts

Gutenberg discontinuity

- Boundary between the outer core and the mantle.

Lower Mantle (Mesosphere)

Plasticity (easily shaped and modelled)

Øranging from approx. 650 km to 2900 km below the surface.

ØApprox. 2250 km thick

ØRich in silicon and magnesium

ØApproximately 3000-5000ºC

Upper Mantle

320-250 km in diameter. Divided into two parts:

& Lithosphere

Lithosphere

outermost shell, which is defined by its rigidity. It is partly composed of the crust. Solid and brittle.

Asthenosphere

highly viscous and relatively weak. Responsible for plate tectonic movement. Has some degree of plasticity.

Crust

-Outermost layer of the earth

Mohorovičić (Moho) discontinuity

 Boundary between the mantle and the crust

Continental crust

Ø30-50 km thick

Øcomposed of less dense rocks like granite

Oceanic crust

Ø5-10 km thick

Øprimarily composed by dense rocks like, basalt and diabase

Øyounger than its counterpart

Geosphere/Lithosphere

-Refers to the solid Earth

-Composed of naturally-occurring minerals, rocks, and organic material. Collectively called Regolith

-Made up of Rocks

Rocks

-Naturally occurring solid cluster of one or more minerals

Igneous

ØFormed through the cooling and solidification of lava and or magma

Intrusive

- Solidifies within the crust

Extrusive

Rocks that solidifies at the surface of the Earth

Sedimentary

ØFormed by the deposition of the weathered remains of other rock at the Earth’s surface

Deposition

- a process in which sediments accumulate and added to the land mass

Lithification

- unconsolidated materials solidify into rocks.

Chemical

- Formed by precipitation of materials from water

Clastic

formed from the debris due to mechanical weathering of rocks

Metamorphic

ØFormed through the transformation, either by heat or pressure, of existing rocks.

Foliated

– metamorphic rocks that exhibited layering. It occurs during recrystallization

Non-foliated

rocks that has no foliation