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Exam 2 Review Sheet

Exam 2 Review Sheet - Relative Age Ages events based on...

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Relative Age: Ages events based on their relevance to another event Absolute Age: The Number of years elapsed from an event until now Nicholas Steno: Laid the foundation for Stratigraphy (layering of rocks), and these principles: Principle of Lateral Continuity: States that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or other erosional feature, can be assumed to be originally continuous. Principle of Original Horizontality: Basically the same as Lateral Continuity, the idea that sediment is deposited under the influence of gravity. Principle of Superposition: The idea that a layer is younger than the one below it and older than the one above it. Unconformity: a surface between two layers that were not laid down in an unbroken sequence. Angular Unconformity: A situation where the upper layers overlie a bed below that had been folded by tectonic processes and eroded to an almost even plane so that the two sets of layers have unparallel bedding planes. Disconformity: A situation where upper layers overlie an erosional surface. Nonconformity: When upper beds overlie metamorphic or igneous rocks. Principle of Cross-Cutting Relationships: The intrusion (such as a dike or sill) must be younger than the beds that it cut across. Furthermore, if it stops at an unconformity, the layer that overlies it must be younger still than the intrusion itself. Inclusions: Any material trapped inside another material during its formation William Smith: founded principle of Faunal Succession Principle of Faunal Succession: The layers of sedimentary rocks in an outcrop contain fossils in a definite sequence. Basically, layers with similar fossils are of similar age Adam Sedgwick: Proposed the Devonian period and latter Cambrian period of the geologic timescale. Roderick Impey Murchison: Investigated in England, developed the Silurian System. Lord Kelvin: Developed Kelvin Scale, wanted to know how long it took a rock to go
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from molten to its present state. Radioactive Decay: As time goes on an element becomes radioactive, form of dating. Half-Life: the time required for one-half of the original number of parents atoms to transform to daughter atoms. Carbon-14 dating: Half-life of 5,730 and dates bones and wood. Formation: layers? Bedding: Layering. Strike: line formed by a bedding plane and a horizontal plane. Dip: Angle between the bedding plane and horizontal plane. Stress: Forces Acting on Rocks Strain: How a rocks react, the change. Compression: A force that squeezes together or shortens a rock Tension: A force that stretches a body and tends to pull it apart Shear: A force that pushes two sides of a body in opposite directions Elastic Deformation: Deformed body returns to its original size and shape Plastic Deformation: Ductile deformation, occurs at greater depths where rock is warmer, is a permanent change after stress is removed. Occurs by the slippage of atoms
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Exam 2 Review Sheet - Relative Age Ages events based on...

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