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3 Cards in this Set
- Front
- Back
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Gradual replacement by minarles |
Things like bones teeth and shells which don't decay easily last a long time when buried they are eventually replaced by minerales as they decay forming a rock like substance shaped like the original Surounding sediment turns to rock too but the fossil stays distinct |
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From casts and impressions |
Organism is buried in soft material like clay (moulds to the shape) the clay later hardens around it and organism decays leaving cast A burrow or roots can be preserved to make casts too Foot prints can be pressed into these when soft leaving impression when harden |
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From preservation in places no decay can happen |
1)in Amber and tar pits there is no oxygen or mosture so decay microobs can't survive 2)in glaciers too cold 3)peat bogs too acidic |
