GEOL 1020 Lecture Notes - Lecture 3: Graptolithina, Calcite, Geologic Time Scale
7 Dec 2017
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The denver formation contains the cretaceous-paleogene (k-pg) boundary, but this is not part of its formational definition. Formation: the fundamental rock unit; a mappable body of rock defined by its lithology (i. e. , physical and chemical characteristics of the rock. The precambrian comprises roughly of earth history. Geologic time scale born in the early 19th century. Ex: cambrian comes from cambria" the ancient roman name for wales Subdivisions of time scale are time units called geochronologic units: Chronostratigraphic unit (or time-rock unit) - corresponding body of rock whose deposition defines the time unit boundaries (ex: devonian system) Geologic time scale in 1888: the characteristic fossils of most geologic periods and epochs were established. Fyi: most epochs were named by charles lyell in the 1820s-1830s based on marine mollusks. Index fossil: a species or genus of animal or plant whose fossils are characteristic of a particular span of geologic time and are used for relative dating.
