This has been a work that we've done this term. It has been an exciting experience; but it's true that it isn't an easy work and it can create some nerves in your body.
I had to do a presentation about Earth and its tectonics. I made the presentation like a story, in fact, I firstly explained the earth beginnings and then, I started with the different periods of the Earth formation. After the different periods I concluded with tectonics: the history of the super continents, the nowadays situation and the different types of boundaries.
Here is the hole presentation. I hope you'll enjoy it:
EARTH
As we know, the Earth is the only planet that can support life. This is an amazing fact, considering that it was formed at the same time and trough the same
process as the other planets in the Solar System.
Earth began to form from the same cloud (mostly composed of hydrogen and helium) that formed our sun, the Solar System and even our galaxy. In fact, Earth is still forming and cooling, and it will be in the future.
The sun formed within a cloud of dust and gas that continued to shrink in upon itself by its own gravitational forces. This caused it to undergo the fusion process and give off it light, heat and other type of radiation.
During this process, the remaining clouds of gas and dust that surrounded the sun began to form into smaller lumps called planetesimals, which eventually formed into the planets we know today.
As we know, they are eight and they move around the sun because of gravity forces. If gravity didn't exist, they would move in a straight line in the universe.
Coming back to the Earth, I'm going to continue with the Earth formation. The Earth went through a catastrophic and intense period of formation. This period is called the Pre-Cambrian period and it's divided into three shorter periods: the Hadean, the Archean and the Proterozoic period.
By the Hadean period, Earth was continuously bombarded by asteroids, meteors and comets until it formed into a solid sphere.
As Earth began to take solid form, it had no free oxygen in its atmosphere. Its first atmosphere was also so poisonous, comprised of helium and hydrogen, that nothing would have been able to survive.
Earth's second atmosphere was composed mostly of gases like nitrogen, oxygen, carbon dioxide, argon and other types of gases that were formed by the constant volcanic eruptions that happened during this time. It had also no free oxygen.
By the Archean, the Earth’s surface — or crust — began to cool and stabilise, creating the solid surface with its rocky terrain. Clouds formed as the Earth began to cool, producing enormous volumes of rainwater that formed the oceans.
During this period, first life began to appear and the world’s landmasses began to form. Earth initial life forms were bacteria, which could survive in the highly toxic atmosphere that existed during this time.
Toward the end of the Archean and at the beginning of the Proterozoic period, oxygen-forming photosynthesis began to occur. The first fossils were a type of blue green algae that could photosynthesise.
Some of the most exciting events in Earth’s history and life occurred during this time. The continents began to form and stabilise, creating the super continent Rodinia . Although Rodinia is composed of some of the same land fragments as the more popular super continent, Pangea, they are two different super continents.
Rodinia is thought to have broken up into eight smaller continents. Some of them were called Laurentia, Australia and East Antarctica.
The eight continents later re-assembled into another 'supercontinent' called Pangea. During the formation of this super continents, mountains were formed. For instance, the Urals of nowadays were formed during this time.
Nowadays, we have eight major plates. They are constantly moving and they are situated in the lithosphere. when they hit each other we can have three type of boundaries:
Free oxygen began to build up around the middle of the Proterozoic Period and made way for the emergence of life as we know it today. This increased oxygen created conditions that would not allow most of the existing life to survive and thus made way for the more oxygen-dependent life forms.
By the Holocene period, in the Cambrian Period and also known as the Age of Man, first human species were discovered. But I have to finish here...
Here you have two videos: the first one is more impressive and the second one explains better the tectonics situation of nowadays.
Some about the subject:
1. What type of boundaries can happen?
2. What were the first life forms?
3. Why do the planets of the Solar System move around the sun?
4. In which period of formation do the continents start to form?
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