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Click to play Radioactive Measurement Game!

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Click to play Radioactive Measurement Game!

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The principle of superposition states that if undisturbed, due to gravity, lower layers of rock were deposited first and are therefore older. Newer rocks were formed on top of the older ones.

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How Does Radiocarbon Dating Work? - Instant Egghead #28

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Some unstable elements such as Carbon-14 can be used to tell how old fossils are using what is known as their "half life". We measure the rate of decay of the Carbon-14 atom compared to the stable Carbon-12 atom.

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extra resource

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Fossil dating | Heredity & Evolution | Biology | Khan Academy

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Based on the principle of superposition, we can compare fossils with each other to find the range. Remember: the principle of superposition refers to lower layers of rock forming first and higher layers forming on top of them later.

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https://www.khanacademy.org/science/in-in-class-10-biology/in-in-heredity-and-evolution/in-in-evolution-classification/v/fossil-dating-heredity-evolution-biology-khan-academy
https://archive.cnx.org/specials/d709a8b0-068c-11e6-bcfb-f38266817c66/radioactive-dating-game/#sim-half-life

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Click to play Relative Depth Dating Game

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My first job is to find the fossils . Fossils are found in layers of sedimentary rock . So that's where the team and I go—to places with sedimentary rock. They could be as close as Arizona or as far away as the Gobi Desert in Mongolia!

At the dig site we begin by looking for exposed fossils. When we find something we start digging. We dig slowly and carefully so we don't damage the specimen. Back in the lab, we can study the fossil more closely. Our goal is to determine what kind of animal it was and when it lived.

Want to find out how the history of life is written in the rocks? Let's go!

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My first job is to find the fossils . Fossils are found in layers of sedimentary rock . So that's where the team and I go-to places with sedimentary rock. They could be as close as Arizona or as far away as the Gobi Desert in Mongolia!