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Category:Geology and Earth Formation Definitions you should know:

1. Relative age: The age of a rock or formation given relative to other rocks or formation, usually defined as a zone fossil name.

2. Absolute age: An approximate age for an archaeological or paleontological

3. Law of superposition: Key axiom based on observations of natural history that is a foundational principle of sedimentary stratigraphy and so of other geology dependent natural sciences

4. Unconformity: A surface of contact between two groups of unconformable strata.

5. Index fossils:

A fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found.

6. Radioactive decay: The spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation

7. Half-life: (The time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate))

"Facts about geology time"

The geological time scale is used to show us a record of life forms that have taken place during Earth’s history. If you were to look at Earth’s history in a day humans were developed a second before midnight. There are three different ways in which geological time is broken down.

They are eras, periods and epochs.

Eras are the longest units of time and have the biggest range. Periods break down the eras. Epochs break down the periods. There are three main eras, which are the Paleozoic, Mesozoic and Cenozoic. The time frame before the Paleozoic is known as the Precambrian time that takes up 88% of Earth’s history.

Precambrian Time: 4.6 billion years – 544 million years                                    = 4,056 million years

Paleozoic Era: 544 million years – 245 million years = 299 million years

Mesozoic Era: 245 million years – 65 million years = 180 million years

Cenozoic Era: 65 million years – 0 (Present day) = 65 million years

PRECAMBRIAN TIME

Earth is 4.6 billion years old. Earliest life forms of single-celled organisms are dated back to around 3.5 billion years ago. Energy from the sun was used from organisms 2.5 billion year ago.

PALEOZOIC ERA

Life explodes at the beginning of this era, known as the “Cambrian explosion.” A large number of organisms develop. During the Ordovician and Silurian period’s vertebrates, an animal with a backbone, appeared as jawless fish. During the Devonian period animals began to move to land. Amphibians, an animal that lives half its life on land and half its life in water, appeared as lungfish, which evolved. Mass extinction ends the Paleozoic era. As much as 95% of the ocean life disappeared as a cause of this mass extinction. At the end of the Paleozoic era, during the Permian period, 260 million year ago, all of Earth’s continents were one. They called great mass of land Pangaea the supercontinent.

MESOZOIC ERA

The Mesozoic era is known as the “age of reptiles” because reptiles were so Abundant at this time. This is the era in which dinosaurs roamed the earth. Pangaea starts to break apart at the end of the fist period called the Triassic period. Mammals, warm-blooded vertebrate that feeds it young milk, also developed during the Triassic period. During the Jurassic period dinosaurs became the dominant animals on the land. In the Cretaceous period Tyrannosaurus rex ruled the land, along with flowering plants evolved. Another mass extinction took place 65 million years ago. Scientists think that an object that struck Earth caused the mass extinction. This mass extinction killed off all of the dinosaurs and over half of the plants and animals.

CENOZOIC ERA

Mammals evolved and lived in many different environments such as in water, on land and in the air. During the Tertiary period whales and dolphins evolved. The Quaternary period the climate cooled causing a series of ice ages. The fossil records show that human evolved around 3.5 million years ago.

"Questions and answers"

1. What is the geological time scale? It is sort of like a chart that shows what us recorded forms of life from long ago.

2. Put the three units of time into order from the biggest to smallest. Period, Era, Epoch. Era, period, and epoch.

3. What is the time frame for the Precambrian time period? 4,056 million years

4. If you could travel back in time 150 million years, what year and period would you be in? Mesozoic era is the period that we would be in.

5.	What made the “Cambrian explosion” so important to the history of the Earth? It was the time that the first major animal groups in fossil record.

6. How did dinosaurs becoming extinct help mammals evolve? If the dinosaurs did not become extinct than it would come to the point where there would be no mammals left. The reason why is because they had killing machines as dinosaurs. It would be the every mammal for themselves because the dinosaurs would never think of holding themselves back. So I think it helped because there were still mammals left in the ftermath so it all worked out.

7. What was Pangaea? Pangaea was a supercontinent that happened during the late Paleozoic and early Mesozoic eras, forming about 300 million years ago and beginning to crack around 200 million years ago, before the component continents were separated into their current configurations.

8. How do you think that mass extinctions have affected the evolution of species on Earth? I think that I would have to say that mass extinctions saved our lives. If we did not have the dinosaur mass distinction we would not be here. The dinosaurs would have taken us over. There would be nothing here. I would not be writing this paper. It would come to the fact that I would not be answering to this questions. In fact this would be my answer “

Just a brief summary

PRECAMBRIAN TIME- the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago

PALEOZOIC ERA- Paleozoic: from 544 million to about 230 million years ago.

CAMBRIAN PERIOD- Cambrian: from 544 million to about 500 million years ago; marine invertebrates.

ORDOVICIAN PERIOD- Ordovician: from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds.

SILURIAN PERIOD- Silurian: from 425 million to 405 million years ago; first air-breathing animals

DEVONIAN PERIOD- Devonian: from 405 million to 345 million years ago; preponderance of fishes and appearance of amphibians and ammonites.

CARBONIFEROUS PERIOD- Carboniferous: from 345 million to 280 million years ago.

PERMIAN PERIOD- Permian: from 280 million to 230 million years ago; reptiles.

MESOZOIC ERA- The Mesozoic Era is a period from about 250 million years ago to about 67 million years ago.

JURASSIC PERIOD- Jurassic: from 190 million to 135 million years ago; dinosaurs; conifers.

CRETACEOUS PERIOD- Cretaceous: from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants

CENOZOIC ERA- Cenozoic: approximately the last 63 million years.

TERTIARY PERIOD- Tertiary: from 63 million to 2 million years ago. QUANTERNARY PERIOD- Quaternary: last 2 million years

Extra Facts to know

Precambrian period-so in hash conditions life started to evolve and flourish.

Cambrian and Ordovician period- this was when life was under water.

Silurian and Devonian period- this was when land and water were forming together.

Carboniferous period- this is when life on land was a swamp and many bugs lived in it.

Permian period- this is when reptiles started to evolve on land.

Mesozoic era- this is when there were multiple type’s reptiles and dinosaurs.

Tertiary period- this was when mammals started to multiply.

Quaternary period- this is when the ice age happened. It struck many animals.