What has happened through earth geologic history? Scientists have figured out a way to make a time scale by using rock sediment. By looking at a stacked arrangement of rocks scientists can determine the age of fossils and rocks called a geologic column. Through this geologic column scientist have been able to break the earth's history down into different periods of time.
The sediment found in rock layers can determine what the Earth's surface and climate was like at a given time in history. Scientists have given names to these certain points of time or eras in history. The oldest Era is the Precambrian Eras dating back further then 4 billion years ago. The Next era is the Paleozoic Era starting 570 million years ago. The Mesozoic Era then began after 325 million years of the Paleozoic Era. Then 65 million years ago the Cenozoic Era began dating up to recent history.
The Precambrian Era or the time dating back to the formation of the Earth 4.6 billion years ago is most of the Earth History. During this time the Earth was mainly covered by water. Volcanic Eruptions, and Mountain building to place developing the Earth's surface. During this time there was minimal life except for life forms such as marine worms, jellyfish and bacteria. .
The Paleozoic era is broken up into many periods because the amount of life during this time. Also during this time the continent of Pangaea was formed because of tectonic collisions. Fish began to swim the oceans and plants began to grow on land. The most dominant life form during this time was mollusks or sea creatures with hard shells. At the end of this Era insects and invertebrates began to strive on land. .
The Mesozoic Era was when the continent of Pangaea broke up into smaller continents. This time was greatly known for the number of reptiles. During this time dinosaurs began to evolve and plant life grew with great abundance. There were to types of dinosaurs, plant eaters and meat eaters.