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study+guide+2 (1) - 1 Study Guide Number 2 Geologic Time:...

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1 Study Guide Number 2 Geologic Time : Sedimentary rocks provide best evidence of earth history; Geologic Time Scale - put rocks into a time perspective. We distinguish two types of geologic time: 1) Relative ages or dating 2) Absolute age; Relative Dating and the Stratigraphic Record 1)the principle of original horizontality (2) the principle of superposition ; Lithostratigraphy: lithostratigraphic units: bodies of sedimentary, extrusive igneous, metavolcanic or metasedimetary rock distinguished on the basis of lithologic (observable rock) characteristics. They carry no connotation of age. Generally map and identify formations. - the fundamental unit of lithostratigraphy; Contacts Between Units - The Mark of Missing Time; Layers of rock are said to be conformable when they have been deposited essentially without interruption; unconformity - a surface of nondeposition or erosion; Hiatus: actual time loss; Types of unconformities: 1) angular unconformity - a surface separating tilted or folded strata from overlying undisturbed strata; 2) disconformity - a surface of unconformity separating essentially parallel strata; Principle of cross-cutting relationships; Inclusions. Facies - set of characteristics of a rock body representing a particular local geologic environment. Fossils: used to compare two widely spaced geologic areas; to detect missing time intervals; to correlate the ages of rocks Fossils - the remains of ancient organisms. study of history of ancient life and fossils - paleontology. Correlation: William Smith (1793) - surveyor in southern England; fossils could date relative ages of sedimentary rocks. faunal succession index fossils - fossil species and genera that are especially well suited to correlation procedures. Rock Stratigraphic Units - mappable assemblages of strata distinguishable by physical criteria.
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study+guide+2 (1) - 1 Study Guide Number 2 Geologic Time:...

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