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FOSSILS

FOSSILS. What is a fossil?. Remains of once living animals or plants Represent ancestors of organisms living today. Does every organism turn into a fossil?. No - Normally they rot or get eaten If the conditions are correct they can be buried quickly and fossilized 5 Different steps.

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FOSSILS

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  1. FOSSILS

  2. What is a fossil? • Remains of once living animals or plants • Represent ancestors of organisms living today

  3. Does every organism turn into a fossil? • No- Normally they rot or get eaten • If the conditions are correct they can be buried quickly and fossilized • 5 Different steps

  4. How are fossils formed? • Animal dies and is buried by sediment • Extreme pressure turns sediment into stone • Skeleton dissolves and leaves a hole/mold • Dissolved by ground water • Minerals crystallize in hole and a cast is formed • Mineral rich water enters mold and leaves minerals • Millions of years later, the fossil is exposed on the Earths surface • Earthquakes, mountain building, construction, digging/drilling

  5. What do fossils tell us? • How plants and animals used to live • Individual? Group? • Where plants and animals used to live • How plants and animals from the past are related to the ones today • How plants and animals develop • What type of animals/plants used to be present

  6. What different types of fossils are there? • Body fossils • Tell us what the animal/plant looked like • Ex: Petrified wood, frozen mammoths, amber • Trace fossils • Tell us what the animal did • Ex. Footprints, trackways, Coprolites (poo)

  7. How do we get information about fossils? • Relative dating • Rock Layers • Absolute dating • Radioactive Half-Life

  8. How are rock layers formed? • Rocks are… • Melted • Cooled • Weathered/ Eroded • Compacted/ Cemented • Heated/ Pressurized

  9. How are rock layers formed? Rock layers = Sedimentary Rocks • Formed when particles are deposited on top of other particles • Pressure pushes down • Dissolved minerals form natural glue • Creates rocks at or near the surface

  10. Why are rock layers important? • Tell our history • Geologic Column • Ideal sequence of rock layers that contain known fossils and rock formations. • Arranged from oldest to youngest • Gaps in history • Erosion • Natural events – Folding, Faults, Volcanoes

  11. What do the rock layers tell us? • When events happened • In general rocks in the same layer happened at the same time • Fossils in the same layer lived at the same time

  12. What is radioactive decay? • Certain naturally occurring elements are radioactive and they break down at predictable rates • Scientists measure the half-life of elements • Half life = the time it takes for half the radioactive element to break down • Scientists compare the amount of an element to the initial amount and the half-life to determine age

  13. Why is radioactive decay helpful? • Also called carbon dating • Allows us to calculate an age • Cannot be used for objects older than 70,000 years

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