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The Folk classification is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas. ==Folk's sandstone (clastic) classification== Folk's philosophy is that the name of a rock must convey as much information as possible without being a complete description. For this, he proposed five important properties of sandstones to use as defining characteristics. These five properties are: grain size, chemically precipitated cements, textural maturity, miscellaneous transported constituents, and clan designation. Folk's fivefold name must be in the following format: :(Grain size): (chemically precipitated cements) (textural maturity) (miscellaneous transported constituents) (clan designation) However, Folk stated that cements and miscellaneous transported constituents are optional categories as they are not always observed. The other three properties should always be mentioned. The following are examples of rock names using Folk's fivefold name: :Coarse sandstone: calcitic submature micaceous subarkose :Fine sandstone: supermature quartzarenite :Sandy granule conglomerate: calcitic submature calclithite :Very fine sandstone: chert-cemented submature quartzose phyllarenite :Clayey very fine sandstone: immature fossiliferous plagioclase arkose 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Folk classification」の詳細全文を読む スポンサード リンク
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