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The Piacenzian is in the international geologic timescale the upper stage or latest age of the Pliocene. It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma (million years ago). The Piacenzian is on top of the Zanclean and is followed by the Gelasian (part of the Pleistocene). The Piacenzian is roughly coeval with the European Land Mammal Mega Zone MN 16, overlaps the late Chapadmalalan and early Uquian South American Land Mammal Ages, and falls inside the more extensive Blancan North American Land Mammal Age. It also correlates with regional stages like the Astian, Redonian, Waltonian (England), Reuverian (Netherlands) or Romanian (Central Europe). ==Definition== The Piacenzian was introduced in scientific literature by Swiss stratigrapher Karl Mayer-Eymar in 1858. It is named after the Italian city of Piacenza. The base of the Piacenzian is at the base of magnetic chronozone C2An (the base of the Gauss chronozone and at the extinction of the planktonic forams ''Globorotalia margaritae'' and ''Pulleniatina primalis''. The GSSP for the Piacenzian stage is at Punta Piccola on Sicily, Italy.〔Castradori ''et al.'' (1998)〕 The top of the Piacenzian (the base of the Quaternary system and the Pleistocene series) is defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone (at the Gauss-Matuyama reversal), and isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils: ''Discoaster pentaradiatus'' and ''Discoaster surculus''.〔Gadstein ''et al.'' (2005), p. 28; Rio ''et al.'' (1998)〕 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「Piacenzian」の詳細全文を読む スポンサード リンク
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