Hazel Research

8/12/2019 Hazel Research

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Earths Vital Statistics

Shape: almost spherical

Size: 6400km in radius

Average density: 5.5gm/cc; surface: 3gm/cc or less;centre may be 10-15gm/cc

Temperature: core: 2200-2750ocPressure: core: 3-4 million times theatmospheric pressure at sea level

COMPOSITION AND STRUCTURE OF THE EARTH

The Earth is the third planet in the solar system and is about 4600 billion years old. Over 65% of

the surface is covered in water, the remainder broken up into five continental land masses.

The Earth rotates in an anti clockwise direction about an axis tilted over at 23.5o. The Earth is an

oblate spheroid, flattened at the poles and bulging at equator.

CHEMICAL COMPOSITION

crust. The outermost rock layer, divided into continental and oceanic crust. The continental crustis 25-90 km thick and is mostly granite and andesite. The oceanic crust is 6-11 km thick and

mostly basalt.

mantle. The mantle stretches from the below the crust to 2900 km below the surface. The upper

part is partially molten and the lower part is very dense. The main mantle rock is peridotite.

core. The core is about 7000 km in diameter with a temperature of 6000o

C and a pressure of over3 million atmospheres. The inner core is a lumpy solid iron sphere and the outer core is a thick

liquid iron layer.

PHYSICAL STRUCTURE

lithosphere. Equivalent in part to the crust, the lithosphere comprises of a number of tectonicplates that 'float' on the asthenosphere.

asthenosphere. Ductile rocks that lie from below the lithosphere to 250 km below the surface.

mesosphere. Solid rocks below the asthenosphere.

ROCK CYCLE

There are 3 rock types: igneous rocks, sedimentaryrocks, and metamorphic rocks.The rock cycle

is an ongoing process, beginning as rocks are pushed up by tectonic forces, and eroded by wind

and rain. The eroded rocks travel by wind or moving water until they are deposited, settling intolayers. Additional eroded rocks may bury these layers until heat and pressure change the

underlying layers to metamorphic rock. More eroded rocks may squeeze and press the layers into


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sedimentary rocks. Rocks can also be sunk down into the lower layers of the earth by plate

tectonic processes. Buried rocks may also melt and recrystallize into igneous rocks.

Metamorphic, sedimentary, and igneous rocks may then be pushed up by tectonic forces, starting

the rock cycle again.

MINERAL

A mineral is a substance with these characteristics:

Crystalline - and so has an ordered arrangement of atoms Definite chemical composition - for example, quartz (SiO2)

or pyrite (FeS2) - or limited range of compositions (for

example,a complex mineral named hornblende) Naturally occurring

Inorganic (never lived, although graphite, diamond, and

calcite may be bioproducts of organisms)

Properties of Minerals

Hardness Luster

Color

Streak

Cleavage Fracture

Cleavage vs. crystal form

Miscellaneous properties


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Mineral Classification MetalsCombined with oxygen = oxide minerals

Combined with sulfur = sulfide minerals

Not combined with other elements = native(native gold, native copper, etc.)

Silicates (Si is an important ingredient)

Ferromagnesian (Fe, Mg) - dark and dense

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