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a scientific investigation involving an iterative process of empirical observation, hypothesis building (with a predictive or retrodictive component), and testing.
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Two important scientific theories are central to the understanding of Earth History
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Plate Tectonics and Biological Evolution.
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Earth Systems
The sum of the physical, chemical, and biological processes operating on and within the Earth.
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Movement of lithospheric plates across the planet’s surface, which is responsible for the recycling of rocks
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(Liquid, ice, vapor) plays a major role in weathering/erosions and formation of rocks and…
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Source of profound change on Earth’s surface, their effects alter rocks, water systems and the atmosphere
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Drives the type of organisms, amount and distribution of water, speed and variability of weathering of rocks
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Plate tectonics theory
 - The scientific theory that Earth's outer shell, or lithosphere, is composed of pieces that interact with each other as they "float" on a hot deformable asthenosphere
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Uniformitarianism
The principle that processes acting on Earth today have also operated in the geologic past. First articulated by James Hutton, a Scottish physician, farmer, and gelogist.
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Stratigraphy
the science of layerd rocks, developed from three principles first stated by Niels Stenson (Nicolaus Steno). Steno also recognized the importance of chemical dissolution and the precioitation of minerals from solution.
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Stratification of sediments occures as the result of differences in particle size and density. When carried in a current (water or wind), heavier particles tend to settle first, and lighter ones stettle afterward.
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Principles (6)
- Original Horizonatality-rock layers deposited FLAT
- *Lateral Continuity
- Law of Superposition-Old rocks on bottom, young rocks on top
- Cross-Cutting (jelly donut)-fault intrusions are YOUNGER, then layers they cross.
- Inclusions (coco chip cookies)
- Biotic Succession-fossils occur in strata in a definate determinable order.
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Principle of superposition
In an undisturbed succession of strata, the oldest strata are at the base of the succession, and the youngest strata are at the topo of the sucession.
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Principle of original lateral continuity
At the time of deposition, a sedimentary unit extended laterally and continuously in all directions until it thinned out or otherwise reached the limits of its depositional range.
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Principle of horizontality
Sedimentary strata were originally deposited nearly horizontally and parallel to Earth's surface.
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Principle of cross-cutting relationships
A rock unit, or fault that cuts another geologic unit is younger than the unit that was cut.
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Principle of included fragments
Fragments of a rock or sediment body contained within another rock or sediment are from a preexisting (older) rock or sediment than the one in which they are contained.
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Interfingering relationships
Indicated by z-shaped "shazam lines."
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Unconformities
An unconformity is a contact that represents a significant time difference between adjacent rock units.
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Angular Unconformity
Contact separating younger & older beds that are at an angle to each other
Older beds typically dip more steeply
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Making an angular unconformity
- Deposition
- Folding/Uplift
- Erosion
- Subsidence/more deposition
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Nonconformity
Where sedimentary rocks overlie older plutonic igneous or metamorphic rocks
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Making a Nonconformity
- deposition
- tilting & uplift& erosion
- intrusion
- deposition
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Disconformity
A contact between parallel younger & older sedimentary layers
Relatively hard to see; need to look for fossils & inclusions
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