lec 15 relative time scale - University of Wisconsin–Madison · 2004-02-26 · Copyr ght @...
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Relative time scale
Transcript of lec 15 relative time scale - University of Wisconsin–Madison · 2004-02-26 · Copyr ght @...
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Relative time scale
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Steno
• Niels Stensen (1638-1686) Danish physician and anatomist– Research in Italy in 1660s, published geological
conclusions in 1669 (Prodromus)• Superposition• Original lateral continuity• Original horizontality
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Strata Smith
• William Smith (1769-1839) English surveyor– Made practical observation that each individual
rock layer contained its own specific assemblage of fossils (Faunal Succession: first written down in 1796)
– Published first geologic map of England (1815)
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Geologic systems
• Large thicknesses of sedimentary rocks that crop out over a region
• Descriptive names originally, based on rock type (Cb, K)
• Later named for geographic region where exposed• Using faunal succession principle, systems based
on fossil content rather than lithology• By c. 1840 most of the systems recognized and
named (Ordovician in 1879)
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