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30 Cards in this Set
- Front
- Back
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What two types of age determinations can be made?
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1. Quantitative age measurement
2. Qualitative age measurement |
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Quantitative age measurement refers to ...
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absolute age; this method gives the age of formation of the rock in terms of years before the present.
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Absolute age of a rock is determined by ...
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the technique of radiometric age dating
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Qualitative age measurement refers to...
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relative age; found by the spatial relations between rock bodies
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Relative age indicates...
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whether the rock is older or younger with respect to another spatially related rock body.
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Niels Stens (Nicholas Steno)
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Danish physician who developed laws of sediment depostitation now known as Steno's Laws.
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The Principle of Superposition
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any undisturbed process of sediment deposition, the oldest material is on the bottom and the youngest on the top.
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Charles Lyell
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Scientist who further developed important relative age relationship "laws." Specifically, disturbed sediment from erosion, faulting, or igneous intrusions.
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Principle of Cross-cutting Relationships
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if a package of sedimentary strata is cross-cut by another rock, the rock that is cross-cut is older
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Principle of Inclusions indicates...
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that the inclusions must be older than the rock in which they are included.
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Unconformity
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a buried erosion surface that represents a break of significant duration in the geologic record
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Hiatus
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A laps or break in continuity
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Types of unconformity
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Nonconformiy
Angular Unconformity Disconformity |
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Nonconformity
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An unconformity developed between sedimentary rocks and older rocks that had been eroded before the sedimentary rocks were deposited
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Angular Unconfomity
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an unconformity in which older strata are inclined at a different angle than younger strata
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Disconformity
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An unconformity in which the bedding planes above and below the break are essentially parallel. Marked by visible erosion surface.
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Paraconformity
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Seperated by a bedding plane
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Rock units
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formations
groups members |
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The purpose of correlation is to
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line up beds to make a complete history of the strata for the geologic area
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How you view correlation
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from bottom to top (oldest to youngest)
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Geologic Map
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an overhead photograph with exposed rocks seen
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Time-rock unit consists of ..
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an assemblage of strata deposited during a particular interval of time.
Example: the bottom of a body of water |
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Time-rock unit correlated from place to place by...
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its contained fossils, in particular whose whose range is restricted to a relatively short span of geologic time
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Lithofacies map
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shows the areal distribution of rock types in either a rock unit or time-rock unit.
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Biofacies map
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shows the areal distribution of organisms
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Geologic Column
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A composite diagram depicting in a columnar form the sequence of rock units for a given locality or region
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Type Sections
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sequences of strata that are located in time by the principle of superpostition and correlated by their fossil assemblages
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Geologic Time is divided into 3 "eons":
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1. The Archaean
2. The Proterozoic 3. The Phanerozoic |
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PreCambrian consists of:
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The Archaean and Proterozoic eons
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The Phanerozoic is divided into 3 eras:
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Paleozoic, Mesozoic, Cenozoic
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