interpreting geologic history
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Interpreting Geologic History. Earth and Space Science Earthcomm : Understanding Your Environment, pages 53-55. Geologic events such as deposition, erosion, folding, faulting, uplift, subsidence, igneous intrusion , volcanism, and metamorphism have changed the crust over time. - PowerPoint PPT PresentationTRANSCRIPT
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Interpreting Geologic History
Earth and Space ScienceEarthcomm: Understanding Your
Environment, pages 53-55
![Page 2: Interpreting Geologic History](https://reader035.vdocument.in/reader035/viewer/2022062811/56816222550346895dd24b83/html5/thumbnails/2.jpg)
• Geologic events such as deposition, erosion, folding, faulting, uplift, subsidence, igneous intrusion, volcanism, and metamorphism have changed the crust over time.
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- Uplift – process where areas of the Earth’s crust are slowly raised due to expansion of the surrounding rock layersrocks tend to expand when heated
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- Subsidence – process where areas of the Earth’s crust slowly sink due to the contraction of surrounding rocks
rocks tend to contract when cooled
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6 Basic Geologic Principles
• Check out this website• YouTube clip• Helpful website
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1. Principle of Superposition• Younger sedimentary and volcanic rocks are
deposited on top of older rocks
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2. Principle of Original Horizontality• Sedimentary and volcanic rocks are laid down
in approximately horizontal layers
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3. Principle of Lateral Continuity• Sedimentary and volcanic rocks are laid down
in layers that are usually much wider (lateral extent) than they are thick
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4. Principle Crosscutting Relationships• If one rock or geologic structure cuts across another rock unit or geologic feature the cutter is younger than the rock which is being cut
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5. The law of included fragments
• The fragments that make up a rock are older than the entire sample.
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6. The Law of Folds or Tilts:• Tilts in rocks are younger than the rocks
themselves.
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Geologic Cross-section #1
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Geologic Cross-section #2
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Geologic Cross-section #3