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Earths History. How did it all start? The big bang theory: 10-15 billion years ago all the galaxies came together into a single point and caused an explosion.

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Presentation on theme: "Earths History. How did it all start? The big bang theory: 10-15 billion years ago all the galaxies came together into a single point and caused an explosion."— Presentation transcript:

1 Earths History

2 How did it all start? The big bang theory: billion years ago all the galaxies came together into a single point and caused an explosion that scientists call the big bang Since then the universe has been expanding outwards

3 Formation of the solar system About 5 billion years ago a cloud of gas and dust collapsed to form our solar system The gas at the center was hot and dense enough for nuclear fusion to form the sun The remaining dust formed planets

4 Earth at the beginning The earth is 4.54 billion years old At the beginning all the continents we have today were joined as one supercontinent called Pangaea meaning all lands According Alfred Wegener, Pangaea existed around 300 million years ago It broke into 7 different parts by the process of continental drift

5 Wegeners Theory Wegeners theory of continental drift led to the study of plate tectonics. The earth continents are floating pieces of earths crust that move due to sea floor spreading Evidence of Wegeneres theory includes land form, fossils and climates

6 Earths Crust All the landforms on earth are either continental or oceanic crust, continental being that above water, oceanic being the crust below water Mountains are formed from colliding continental plates-the Himalayas are the result of the Indian plate crashing into the Eurasian plate millions of years ago, and even today theyre still growing In the ocean there are cracks in the crust such as mid-ocean ridges and trenches, where subduction and sea floor spreading takes place, causing the continents to move as if they were on a conveyor belt

7 Origin of life Life has changed on Earth and still is Evolution- is the theory that organisms adapt to there environment and change over time Life on Earth started with microorganisms; bacteria, algea, and protozoans. They evolved to be full organisms and start life on Earth

8 Aging on Earth Erosion: Water and wind can carry erosion; broken down sedimentary rock, sand, rock, dirt. Weathering: when rocks and minerals get broken down into smaller and smaller pieces. Caused by; extreme temperatures, water, and ice. Deposition: This is when sediment is deposited somewhere like a delta or riverbank.

9 Aging on Earth cont. We can also tell how old earth is by Fossils fossils: evidence of early life forms preserved in a rock Molds/Casts- hallowed out bones, then dissolved and filled in with other hard material leaving the imprint This can also be done with tracks of organism that get preserved in soil

10 RADIOACTIVE DATING This was a way to date back fossils helping us find out more about Earth. RADIOACTIVE ISOTOPES-atoms of elements that give off radiation RADIOACTIVE DECAY- when a radioactive isotope changes into a stable element

11 Sources cited: WebQuest.html WebQuest.html my_the_wormy/weatheringerosionde position.html


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