How is the age of the Earth determined Vocabulary Geologic Time Scale Law of Superposition Eon Epoch Era Period Intrusion Cenozoic Ice Cores Mesozoic Relative Age Paleozoic Absolute Age ID: 1025491
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1. Geologic TimeEssential Question:How is the age of the Earth determined?
2. VocabularyGeologic Time Scale Law of SuperpositionEon, Epoch, Era, Period IntrusionCenozoic Ice CoresMesozoic Relative AgePaleozoic Absolute AgePrecambrian Radioactive DatingIndex Fossil
3. ConceptGeologic Time EventsMajor eras of historyHow fossils/rocks are dated
4. http://www.youtube.com/watch?v=7PQURsc2SYs
5. Geologic Time ScaleTimeline that organizes major events in Earth’s history, from Earth’s formation to present day.Not organized by number of years! (Can be different amounts of time.)For the first 1 billion years, there was no life on Earth.
6. EonLongest unit of time on the scale.Most fossils come from most recent eon, the Phanerozoic.
7. EraNext longest unit of time; divided up by mass extinctions.Mass extinctions – when many species go extinct over short time period. Shown in rocks when certain fossils disappear, and others begin.Can be caused by a catastrophe.
8. Mass Extinctions VideoPlease take notes on each extinction event in your Lab NB.https://www.youtube.com/watch?v=FlUes_NPa6MName of Extinction: When? Why?1.2.3.4.5.
9. Period2nd shortest unit of time.Divided up by unique rock layers.Associated with specific fossils.
10. EpochShortest unit of time on the scale.
11. PrecambrianMost of Earth’s early history, about the first 3.5 billion years.No life existed yet on early Earth, so there are few fossils from this time.Most of the fossils found are single-celled and from the very end of the Precambrian.The end of this time is known as the Cambrian Explosion, when many different life forms developed.
12. PaleozoicEra when many life forms began to develop, including the first….Fish, insects, plants, amphibians, and reptiles.
13. MesozoicThe era of the first….Dinosaurs, mammals, birds, flowering plants.
14. CenozoicMost recent era (65 mya to present day).Rise of the mammals (became dominant species).Dinosaurs extinct.Humans appeared .
15. Relative AgeAge of fossils compared with other fossils.Fossils near surface are YOUNGER.Fossils near bottom are OLDER.Does NOT give an exact age in years.
16. Law of SuperpositionOlder layers of rock lie underneath younger layers of rockSedimentary – layers are deposited in order..This means….Older fossils/organisms are found on the bottom and newer fossils/organisms are found near the top!
17. https://www.youtube.com/watch?v=YgE-dSx-fPc
18. IntrusionWhen magma pushed up through rock layers and forms a new vertical layer – igneous rock.It becomes the newest/youngest section of rock, even though it goes from bottom to top.
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20. Ice CoresCylinder of ice removed from an ice sheet where layers of snow build up each year.Contain evidence about Earth in the layers….Bubbles trapped – atmospheric conditions.Dust, volcanic ash, CO2 – changes in atmosphere.Pollen trapped – what types of plants lived.
21. Absolute AgeThe actual age in years of a fossil or rock.Absolute Age is found by Radioactive Dating.Rock layers can change, so we can only estimate the actual age of Earth, which is around 4.5 billion years old.
22. Radioactive DatingMeasures age of fossil/rock by comparing its radioactive substance decay rate.Two elements used are Uranium and Carbon-14. They decay at a rate scientists can measure, which can tell scientists the age of the fossils they are contained in.
23. https://www.youtube.com/watch?v=Q6OLBVDbJoI
24. Index Fossils Provide pretty accurate info about age of a rock layer.Fossils that existed for a short time period that scientists have measured in years.Can be compared to location of newly found fossils to estimate age of those fossils.
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