12.2 Fossils: Evidence of Past Life

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12.2 Fossils: Evidence of Past Life by Mind Map: 12.2 Fossils: Evidence of Past Life

1. Petrified Fossils: Fossils often form when an organism remains become petrified. In this process mineral rich water soaks into the small cavities and pores of the original organism. The minerals precipitate from the water and fill the spaces.

2. Molds and Casts: Molds and casts are made by sediment dissolved with underground water. It doesn't provide any information about its internal structure

3. Carbon Films: Fossils called carbon films can preserve delicate details of leaves and animals parts. The formation of a carbon film begins when an organism is buried under fine sediment.

4. Preserved Remains: Fossilization preserves all or part of an organism with relativity little change

5. Trace Fossils: Trace fossils are indirect evidence of prehistoric life.

6. Fossil Succession: fossil organisms that succeed one another. Each layer of a fossil can be examined.

7. Theory of Evolution: Life forms have changed over time, evolved, from simpler to more complex forms

8. Fossils and Correlation: Geologists today use index fossils and groups pf fossils to correlate rock layers.

9. Fossils and Past Environments: Fossils can also be used to reconstruct ancient environments. Fossils provide clues to the characteristics of those environments. Fossils can also help geologist build an even more detailed picture of the past environment. Fossils can indicate the former temperature of the water