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QUATERNARY |
INTRODUCTION |
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| More than 90% of the superficial deposits that crop out today on earth surface | ||
| are of quaternary age. This statement alone explains why the study of the quaternary is mostly important ! This deposits represent the only archive we have to retrace fauna, flora, landscape and of course human evolution during the last 1.8 Ma years. And Quaternary is not dead but still ongoing today! | ||
| Administrative framework | ||
| Geologists connected to the archaeological survey of the Jura District are actually active in quaternary geology as well as site processes study [see geoarchaeology]. | ||
| Chronostratigraphic framework | ||
| Quaternary is the last of the three periods that, with the Paleogene and Neogene periods, form the Cenozoic Era. | ||
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Simplified Stratigraphic Chart of the Cenozoic |
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| It spans approximately the last 1.8 Ma; the greater part of it is known as the Pleistocene (1.8 to 0.01 Ma) and the last 10 ka as the Holocene. In a strict geological sense the base of the Quaternary, is defined in a section at a type locality at Vrica in Italy (Aguirre and Pasini, 1985; IUGS-ICS 2001 >>). | ||
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<<--download PDF 600 KB: Aguirre and Pasini, 1985 | |
| Formerly dated at 1.64 Ma., this limit is today placed at 1.81 Ma, with respect to Paleomagnetics (the boundary is some 3 - 6m above the top of the Olduvai normal polarity subchron). Although set by international agreement, there are strong and persistent arguments for returning this boundary to its former placement at about 2.5 Ma. Indeed, this older boundary marks a major global climatic shift from a pre-glacial to glacial world. For ongoing discussion on the establishment of chronostratigraphic standards in the Quaternary, see this paper written by members of the Italian Commission on Stratigraphy (2002), as well as the proposed standardization of the term "Quaternary" by J. Ogg (2004) >> . |
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<<--download PDF 198 KB: Italian Commission on Stratigraphy (2002) | |
| Structural units of the Jura | ||
| The Jura district is subdivided in two structural units : folded Jura in the South and tabular Jura to the North. This subdivision has implications on the type of quaternary processes and deposits. On the tabular Jura, where cenonoic Molasse deposits are scarce, karstic processes affecting the jurassic limestones are dominant. On the contrary, in synclinal valleys of the folded jura, the clayey to sandy detritic Molasse deposits promote fluviatile processes. It must be kept in mind that glacial sheets did not reach the actual Jura district during the cold stadial periods. The region at that time was affected by periglacial processes as recorded by loess deposits, slope deposits and fluviatile terraces. |
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