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37 Cards in this Set
- Front
- Back
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What is an organism? |
Something that was once alive |
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What is a body fossil? |
Hard parts of an organism |
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What is dissolution? |
Process by which minerals of fossils are dissolved away and removed in solution by groundwater |
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What is replacement? |
Atom by atom substitution of ore mineral for another |
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What is a mould? |
Impression of the outside of a fossil |
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What is a cast? |
An infilled fossil void with another material |
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How many different types of preservation are there? |
4 |
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What are the 4 methods of preservation? |
Replacement Silicification Pyritisation Carbonisation
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What is the most common replacement? |
Aragonite to Calcite |
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Aragonite and calcite are both what? |
Polymorphs |
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Replacement can occur with which groundwater mineral? |
Hematite |
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When are moulds and casts formed? |
When fossils dissolve |
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Is an internal or external mould formed when a rock is broke open? |
External |
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Is an internal or external mould formed if a fossil is infilled with sediment? |
Internal |
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What does carbonisation occur due to? |
Temperature Pressure |
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What is lost during carbonisation? |
Volatiles and gases |
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What increases during carbonisation? |
Carbon content |
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What are animals preserved in during carbonisation? |
A film of carbon |
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What 2 rocks does carbonisation occur in? |
Limestone Chalk |
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What is pyritisation? |
Replacement of metal by FeS |
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When does pyritisation occur? |
When the environment is anaerobic with sulphurous bacteria |
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What do pyritisation causing bacteria use to respire? |
Sulphur |
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What do pyritisation causing convert Sulphur to? |
Bisulfide |
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What 2 environments does pyritisation occur in? |
Deep sea Shallow swamps |
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When does silicification occur? |
When groundwater rich in SiO2 percolates |
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How does silicification occur? |
Dissolved groundwater minerals crystalise and fill in pores |
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What does silicification occur with? |
Wood |
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What is the original composition of fossils? |
Calcite |
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How can high energy effect preservation? |
Fragment fossils |
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How does transport distance effect fossils? |
Fossils can get fragmented over long distances |
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How does burial effect preservation? |
Fast burial allows for preservation |
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How do Oxygen levels effect preservation? |
Low O2 speeds up breakdown |
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Which preserves better: fine sediment or coarse? |
Fine |
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How does diageneis effect preservation? |
Can prevent percolating water |
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What are fossils? |
Remains of living organisms |
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What parts of organisms are mainly preserved? |
Hard parts |
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What 7 factors affect fossilisation? |
Original composition Energy levels Transport distance Burial time O2 levels Size of sediment Diagenesis |
