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27 Cards in this Set
- Front
- Back
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What types of rocks are stratigraphic principles applied to?
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all types of rocks--most commonly to sedimentary rocks
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What are the average %s of sedimentary rock types that cover the Earth's surface for limestone, sandstone, and shale?
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50& limestone, 30% sandstone, 20% shale
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Law of Superposition
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oldest rocks on the bottom, youngest on the top
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Law of Original Horizontality
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all rocks deposited in horizontal manner
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Law of Lateral Continuity
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rocks are deposited continually and extended in all directions until they run into something
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Law of Cross-Cutting Relationships
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if something cuts through a rock, then it is younger than the rock that has been cut through
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Law of Inclusions
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rock fragments in another rock must be older than new rock; there must be a source to have inclusions
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Law of Faunal Succession
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invertabrate animals found in rock layers appear in a predictable sequence
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Principle of Uniformitarianism
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Earth's landscape developed over long periods of time through a variety of slow geologic processes
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What does the phrase, "The Present is the Key to the Past!" mean?
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as far as we know, things that happen today happened the same in the past
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What are unconformities?
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a gap in the rock record
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What events can cause unconformities?
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major sea level changes, major tectonic events, long-term erosion, or long-term deposition
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How much geologic time does it take to make an unconformity?
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tens of millions of years
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Angular Unconformity:
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separates older from younger rocks; the older is tilted at an angle, and the younger is horizontal
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Nonconformity:
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sediments deposited on erosional surface that cuts across igneous or metamorphic rocks
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Disconformity:
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boundary between parallel beds of sedimentary rocks
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What are marine facies?
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they grade laterally into other sedimentary accumulations that were formed at the same time but exhibit different characteristics because their depositional environments were different
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Transgression:
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sea level rises and deeper water facies overlie shallow water facies
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reegression:
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sea level drops and shallow water facies overlie deeper water facies
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what is a fault?
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a fracture in a rock which movement takes place
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normal fault
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headwall drops down compared to the footwall because of tensional forces
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reverse fault
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headwall moves up in relation to the footwall
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thrust fault
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looks like headwall is thrust over the footwall in a 45 degree or less angle
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strike-slip fault
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plates slide past each other, no headwall or footwall
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oblique slip faults
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moves upward and outward-everything moves
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horst fault
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complex fault: a block of rock goes down between two rocks. known as rift valleys on a large scale
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graben fault
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a block of rock moves up between two rocks
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