geo11-02 planet earth by ms. gabo, upm

7/29/2019 Geo11-02 Planet Earth by ms. gabo, upm

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THE PLANET

EARTH


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THE FORMATION OF THE EARTH WAS

AN OFFSHOOT OF THE FORMATION OFTHE UNIVERSE.

Formation of the Universe: Big Bang Theory

Formation of the Solar System: Nebular Hypothesis


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The Universe

ORIGIN: Big Bang Theory

contends that the Universe originated from a

cosmic explosion (origin unknown) that hurled

matter in all directions

first proposed by the Belgian priest Georges

Lematre in the 1920s

Edwin Hubble justified Lematres theory

through observations that the Universe is

continuously expanding; galaxies are moving

away from each other


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THE SOLAR SYSTEM:leftover from the Big

Bang

the sun

the planets

the satellites and rings

comets and asteroids

meteoroids and dust


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OBJECT PERCENTAGE OF MASS

Sun 99.85%

Jupiter 0.10%

all other planets 0.04%

comets 0.01% (?)

satellites and rings 0.00%

asteroids 0.00%

meteoroids and dust 0.0000001% (?)

COMPOSITION OF THE

SOLAR SYSTEM BY MASS

Source: Abell, Morrison, and Wolff, 1987


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The Solar System

ORIGIN: Nebular Hypothesis

proposed by Immanuel Kant and Pierre Simon

de Laplace in the 18th century

the solar system originated from a single

rotating cloud of gas and dust, starting 4.6

billion years ago, which contracted due to

gravity


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The Solar System: Nebular Hypothesis

Time 1

Time 2

Time 3

The Big Bang producedenormous amount ofmatter: rotating cloudof gas and dust.

The rotating gas-dust

cloud began to contractdue to gravity. Most ofthe mass becameconcentrated at thecenter, forming the

SUN.

The remaining mattercondensed to form theplanets: terrestrial andjovian

http://www.aerospaceweb.org/question/astronomy/solar-system/contraction.jpg


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Mercury

VenusEarth

Mars

Jupiter

Saturn

Uranus

Neptune

- inner or terrestrial planets(nearest the sun)

- rocky composition: largely silicaterocks and metals (Si, Fe, O)

- giant or Jovian planets (outer planets;far from the sun)

- lack solid surfaces: in gaseous orliquid form

- composition: light elements (H, He,

Ar, C, O, Ni)

Pluto- neither a terrestrial or Jovian planet

- similar to the icy satellites of theJovian planets


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The Solar System

The scientists agreed that for a celestial body

to qualify as a planet:

a. it must be in orbit around the Sun;

b.it must be large enough that it takes on a

nearly round shape; and

c. it has cleared its orbit of other objects


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The Solar System


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THE EARTH

started as dust ball from the nebular gasand dust brought together by gravity

(accretion), which was heated (heating) andeventually segregated into layers(differentiation) as it cooled

when cooling set in, the denser elements(e.g., iron) sank while the lighter onesfloated out into the surface, creating adifferentiated Earth


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THE DIFFERENTIATED EARTH


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1. Mohorovicic crust mantle

2. Gutenberg core mantle

3. Lehmann outer core inner core

From study of seismic

waves

Discontinuities/Boundaries


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Mechanical layers1. Lithosphere

a. Upper crust brittle; 4-15 km depth

b. Lower crust/uppermost mantle ductile; 15 to 100 or 200 km depth

2. Asthenosphere weak sphere; beneath

the lithosphere and within the uppermantle3. Mesosphere solid, rocky layer

Internal Structure of the Earth


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THE EARTHS VITAL

STATISTICS


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34.6% Iron29.5% Oxygen

15.2% Silicon

12.7% Magnesium

CHEMICAL COMPOSITION

(by mass)


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SHAPE

Oblate spheroid

flattened at the

poles and bulgingat the equator
http://upload.wikimedia.org/wikipedia/commons/9/97/The_Earth_seen_from_Apollo_17.jpg


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SIZE

Circumference = 360 degrees

800 km 7 degrees

Earths circumference was first

calculated by Eratosthenes


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VITAL STATISTICS

Equatorial Radius = 6378 km

Polar Radius = 6357 km

Equatorial Circumference = 40076 km

Polar Circumference = 40008 km

Volume = 260,000,000,000 cu. milesDensity = 5.52 g/cm3


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THE EARTHS LARGE

SCALE FEATURES


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External Features of the Earth

Lithosphere ismade up ofmoderately rigid

plates (mayconsist of oceanicor continental

lithosphere)= 7 major plates +

several smaller

plates


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1. Continents2. Ocean basins


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Thick (30-60 km), old (250-4000 my) and light

It does not subduct

Largest features: Mountain belts

Cratons


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Mountain Belt

First proposed by L. Kober as orogen in 1921

Orogen - an extensive belt of rocks deformed

by orogeny, associated in places with plutonicand metamorphic rocks

An orogeny is an episode of mountain building

Mountain ranges such as the Andes, Alps,

Himalayas and Gran Cordillera


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Thin, geologically young (


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Continental Margin

The transition to the deep ocean basin

The shallowest portion is the shelf

The sloping edge of the continent as it mergesinto the deep ocean basin is the slope

The wedge of sediment that has accumulated

at the base of the slope is the rise

http://www.utdallas.edu/~pujana/oceans/contmar.html


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Oceanic Ridge

Undersea mountain ranges

Deep-ocean Basin


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1. Continents2. Ocean basins


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ISOSTASY

from a Greek word meaning same standing

basically concerned with the buoyancy of the

blocks of the Earths crust as they rest on the

mantle

changes in the load over certain regions

causes the lithosphere to make adjustments

until isostatic equilibrium (i.e., neither rising

or sinking) is reached


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PRATTS THEORY

Elevation is inversely proportional to density.Thus, the higher the mountain, the lower is

its density; that is, light rocks float higher.

depth of compensation


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AIRYS THEORY

Mountains have roots which extend down intothe mantle. Thus, elevation is proportional to the

depth of the underlying root.

depth of compensationrootantiroot


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HOW OLD IS THE EARTH?

Earth: ________

Oldest dated Earth rocks: 3.4 to 4.03 b.y.

Meteorites and moon rocks: ~4.5 b.y.

geo11-02 planet earth by ms. gabo, upm

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