Earth History
The Beginning of Earth:
There are two known theories that explains the origin of Earth. The Core Accretion Model: Our solar system was nothing more than a cloud of dust and gas 4.6 billion years ago. Eventually, gravity condensed material together to form the center of the solar system, the sun. The remaining material formed planets, comets, asteroids, and moons. Earth’s center was created first, and then its mantle and crust. Liquid water formed because Earth was in the Goldilocks zone, where water neither freezes nor evaporates. The location of Earth was crucial to the formation of life as we know it. The moon formed from an impact that sent chunks of rock from Earth into space. Gravity pulled these chunks together, and gravity from the Earth sent it in orbit around the planet. The Disk Instability Model: While the core accretion model is widely accepted among scientists today, it did not explain how the gas planets farther away could form to such a large extent in a short amount of time. Thus, the disk instability model was created to help explain the creation of the gas giants. According to this theory, clumps of gas and dust formed early in the formation of the solar system. These clumps collected quickly, trapping gasses until eventually forming planets. |
The above picture shows how the core accretion model works
The Disk Instability Model: formation of a gas giant
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Where did Earth’s water come from?
More water covers Earth’s surface than land, so it is no wonder that people ponder its origins. Many scientists speculate that water came from ice asteroids and comets that collided with Earth. This would have taken a lot of time, since so much of Earth consists of water. Today, scientists are also speculating that our oceans may have formed much earlier, around the beginnings of the solar system. |
Plate Tectonics:
Plate Tectonics is a theory that explains how Earth’s crust moves over the mantle. Alfred Wegener, a 20th century meteorologist, created a theory known as the “continental drift”, which states that Earth’s continents are moving and were once part of a large landmass known as Pangaea. He proved his theory by showing how the coastlines of South America and Africa and other continents fit into one another, and that similar fossils were found on coastlines thousands of miles apart. |
Earth is divided into multiple chunks of rock known as tectonic plates. These plates move around, separating and colliding with one another, creating different formations.
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Faults are fractures in the Earth's crust and can be classified as normal, reverse or strike-slip.
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Calculating the Age of Rocks:
There are several methods scientists use to calculate the age of a rock. Below are some of the ways they do this:
There are several methods scientists use to calculate the age of a rock. Below are some of the ways they do this:
Index fossils:
Index fossils are fossils that:
- Lived for a short period of time
- Abundant, common fossil
- Widely found in many areas
- Easy to identify
This is a trilobyte. Through fossil examination, we can learn about the life of a trilobyte. We can figure out its age, environment and even its diet.
To learn more about fossils: https://www.youtube.com/watch?v=V8zNrz_l108
Relative Dating:
This process uses the location of a layer of rock to determine age. The lower a layer, the older it is, and vice versa. |
Radiocarbon Dating:
This measures the presence of an isotope of carbon to determine the age of a particular rock. 14C is one particular isotope that decays to form 14N. |
References:
http://www.space.com/19175-how-was-earth-formed.html
http://www.smithsonianmag.com/science-nature/how-did-water-come-to-earth-72037248/?no-ist
https://en.wikipedia.org/wiki/Plate_tectonics
http://www.globalchange.umich.edu/globalchange1/current/lectures/Perry_Samson_lectures/evolution_atm/
Images:
http://api.ning.com/files/HuAMUDZaDIVCNQ67j3fkjGfLjZqudhWWMJjkJfrSEjfFcVPCwt3UXCDeCdrTr8HwQ1vFUERkQmwvpTaDGL0*BxjPLuoOgfT8/EarlyEarth2_560px.jpg?width=560&height=300
https://lh3.googleusercontent.com/KKNdHNY3sdaOAhgTixzlQ1eUWfUp0M_JOjNW3mAdIWg3aa9sHdvRSchntR41CADeXSil4g=s85
http://www.scinexx.de/redaktion/focus/bild8/jupiter16g.jpg
https://farm4.staticflickr.com/3780/10411753546_d8928b8163_o.jpg
http://80c2c58297745c19d00b-3ef697e5597e4211b9a782820054083a.r58.cf2.rackcdn.com/E7177945-24FB-47F4-9EEC-2FEBC97F12B9.jpg
http://www.visionlearning.com/img/library/large_images/image_6996.jpg
http://www.lowbird.com/data/images/2010/03/tektonischeplatten.png
https://courtneysalahub.files.wordpress.com/2014/06/20140606-170619.jpg
http://www.sms-tsunami-warning.com/theme/tsunami/img/fault-types.jpg
https://c2.staticflickr.com/4/3907/15082387710_d1339325cc_b.jpg
http://evolutionblog.yolasite.com/resources/2.png.opt380x432o0,0s380x432.png
http://blogs.egu.eu/network/geojenga/files/2014/12/Radioactivedecay1.jpg
http://www.space.com/19175-how-was-earth-formed.html
http://www.smithsonianmag.com/science-nature/how-did-water-come-to-earth-72037248/?no-ist
https://en.wikipedia.org/wiki/Plate_tectonics
http://www.globalchange.umich.edu/globalchange1/current/lectures/Perry_Samson_lectures/evolution_atm/
Images:
http://api.ning.com/files/HuAMUDZaDIVCNQ67j3fkjGfLjZqudhWWMJjkJfrSEjfFcVPCwt3UXCDeCdrTr8HwQ1vFUERkQmwvpTaDGL0*BxjPLuoOgfT8/EarlyEarth2_560px.jpg?width=560&height=300
https://lh3.googleusercontent.com/KKNdHNY3sdaOAhgTixzlQ1eUWfUp0M_JOjNW3mAdIWg3aa9sHdvRSchntR41CADeXSil4g=s85
http://www.scinexx.de/redaktion/focus/bild8/jupiter16g.jpg
https://farm4.staticflickr.com/3780/10411753546_d8928b8163_o.jpg
http://80c2c58297745c19d00b-3ef697e5597e4211b9a782820054083a.r58.cf2.rackcdn.com/E7177945-24FB-47F4-9EEC-2FEBC97F12B9.jpg
http://www.visionlearning.com/img/library/large_images/image_6996.jpg
http://www.lowbird.com/data/images/2010/03/tektonischeplatten.png
https://courtneysalahub.files.wordpress.com/2014/06/20140606-170619.jpg
http://www.sms-tsunami-warning.com/theme/tsunami/img/fault-types.jpg
https://c2.staticflickr.com/4/3907/15082387710_d1339325cc_b.jpg
http://evolutionblog.yolasite.com/resources/2.png.opt380x432o0,0s380x432.png
http://blogs.egu.eu/network/geojenga/files/2014/12/Radioactivedecay1.jpg