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History of The Earth

The slope of earth surface is various and each of it passes different process. The

differences of the process among other are influenced by power and time. The earth is aplanet that has certain characteristic, so it enables the presence of life.

Nearly all branches of natural science have contributed to the understanding of the main

events of the Earth's past. The age of Earth is approximately one-third of the age of the

universe. Earth formed around 4.578 billion years ago by accretion from the solar nebula.

The theory tells the story in 3 phases:

1. Sun and other planets are still in the form of gas, it is very dense and big fog.

2. The fog rotating and twisting strongly, where the coagulation happens in the center of

the circle that then forms the sun. At the same time another material formed becomes

mass that is smaller than the sun that is called planet, it moves revolving the sun.

3. Those materials grow more larger and keep doing movement regularly revolving the sun

in one fixed orbit and form the composition of the solar family.

Earth is one member planet of our solar system. The occurrence process of the earth is

equal to the sun. Because of its volume is smaller than the sun, its formation process is

faster. In formation process of earth, it happen separation base on to its mass. The heavy

part forms core that is called barisphere (earth core), while the lighter part forms earth’s

crust or often called lithosphere. In cooling process that reaches 100°C, it happen

condensation, then rain, after that, the water fills the lower part of earth and forms watery

layer called hydrosphere. Besides, the earth also covered by air layer called atmosphere

and life layer called biosphere.

In carbon era, the continents unite form the big continent called Pangaea that in Greek

means “the whole world”. Since 1900, geologists have known that outer part of earth’s crust

floats on the soft inner layer.

Theories of continental movement

1. Plate tectonic theory

Plate tectonic is explains the earth’s dynamic process about the formation of moun tain

path, volcanic path, earthquake path, and sedimentation basin on the surface of earth

that is caused by movement of the plate. According to this theory, earth’s crust an d beassumed as very strong raft and relatively cold that floats on elastic asthenosphere

2

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mantel and very hot, or it can be equaled to icy island that floats on the sea water.

There are two kinds of earth’s crust those are oceanic crust that is made up of rock with

base property and very base property, those are found in very deep ocean, and

continental crust that is made up of acidic rock and thicker than oceanic crust. Earth’s

crust covers all of earth’s surface s, but the effect of presence of heat flow that flows in

the astenosphere caused this earth’ s crust breaks to be several smaller parts called

plate of the earth’s crust. Therefore, plate can consists of continental, crust oceanic

crust or both.

According to Alfred Wegener, continents existing at it is now, formed by one super-

continent. Because of the presence of big continent movement in south to west or

north, it happen the following things:

1) The oceans and continents float by separately.

2) Atlantic Ocean is more larger because American continent moves to the west

direction.

3) The presence of big earthquake along the fault of St. Andreas, near the west coast

of United Sates.

Figure 2.1. Super-continent Pangaea

2. Contraction theory

Created by Des Cartes , according to contraction theory “that our earth decreases,

wrinkles, because of cooling so that happens valleys”

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3. Ed Suess’s theory

According to Suess, the similarity of geological formation found in Shout America, India,

Australia and Antarctica is caused by unification of land, the united land is called

Gondwana Continent.

4. American Researchers Team

The result of the research, it is proved that South Pole 200 billion years ago lies near the

equator. Therefore, it should be at that time in South Pole is found animals and plants.

Continuously, in 1969 in South pole found fossil of jaw bone of ancient fresh water

amphibian that its shape is like salamander with characteristic its head is flat and its

body is big and heavy. The kind of that fossil is found in region of South and North

America.

Figure 2.2. The break-up of Pangaea and the drift of the continents

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Solar System

The Solar System (including the Earth) formed from a large, rotating cloud of interstellar dust

and gas called the solar nebula, orbiting the Milky Way' s galactic center. It was composed of

hydrogen and helium created shortly after the Big Bang 13.7 Ga (gigaannum, a unit of timeequal to 10 9 years, or one billion years) and heavier elements ejected by supernovas. About

4.6 Ga, the solar nebula began to contract, possibly due to the shock wave of a nearby

supernova. Such a shock wave would have also caused the nebula to rotate and gain

angular momentum. As the cloud began to accelerate its rotation, gravity and inertia

flattened it into a protoplanetary disk oriented perpendicularly to its axis of rotation. Most of

the mass concentrated in the middle and began to heat up, but small perturbations due to

collisions and the angular momentum of other large debris created the means by which

protoplanets up to several kilometers in length began to form, orbiting the nebular center.

Figure 2.3. illustration of the birth of the solar system

The infall of material, increase in rotational speed and the crush of gravity created an

enormous amount of kinetic energy at the center. Its inability to transfer that energy away

through any other process at a rate capable of relieving the build-up resulted in the disk's

center heating up. Ultimately, nuclear fusion of hydrogen into helium began, and eventually,

after contraction, a T Tauri star ignited to create the Sun. Meanwhile, as gravity caused

matter to condense around the previously perturbed objects outside the gravitational grasp

of the new sun, dust particles and the rest of the protoplanetary disk began separating into

rings. Successively larger fragments collided with one another and became larger objects,

ultimately becoming protoplanets. These included one collection about 150 million kilometersfrom the center: Earth. The planet formed about 4.54 billion years ago (within an uncertainty

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