Sudden or extended changes in climate have been the trigger for five massive extinctions throughout Earth's history. Carmina Virgili, a geologist, became highly interested in one of them: the Triassic-Permian extinction, which caused the extinction of 96% of species 250 million years ago.
She was an expert on Triassic-Permian stratigraphy, an agitated era with many changes.
How did she do it?
She used the fundamental concepts and methods that geologists use to sequence geological events such as the following:
1.- Principle or law?
Complete the following table by indicating if each statement about a stratigraphic sequence is a "Principle" or a "Law".
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| Sedimentary sequenc | Principle or law? | |
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Principle It usually happens |
Law It always happens |
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Superposition of strata – "the top layer is the youngest one". |
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Cross-cutting relationships – "any feature that cuts across another feature, has to be younger". |
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Inclusions – "a feature that is included in another, must be older than the feature that contains it". |
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2.- Applying the principles
Apply the principles to find out the temporal relationships in:
· A map.
