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- Marker_horizon abstract "Marker horizons or chronohorizons or marker beds are stratigraphic units of the same age and of such distinctive composition and appearance, that, despite their presence in separate geographic locations, there is no doubt about their being of equivalent age (isochronous) and of common origin. Such clear markers facilitate the correlation of strata, and used in conjunction with fossil floral and faunal assemblages and paleomagnetism, permit the mapping of land masses and bodies of water throughout the history of the earth.Palynology, the study of fossil pollens and spores, routinely works out the stratigraphy of rocks by comparing pollen and spore assemblages with those of well-known layers - a tool frequently used by petroleum exploration companies in the search for new fields. The fossilised teeth or elements of Conodonts are an equally useful tool.The ejecta from volcanoes and bolide impacts create useful markers, as different volcanic eruptions and impacts produce beds with distinctive compositions. Marker horizons of tephra are used as a dating tool in archaeology, since the dates of eruptions are generally well-established.One particular bolide impact 66 million years ago, Chicxulub, is controversially held to have led to a major extinction event and produced an iridium anomaly that occurs in a thin, global layer of clay marking the Cretaceous–Paleogene boundary. Iridium layers are associated with bolide impacts and are not unique, but when occurring in conjunction with the extinction of specialised tropical planktic foraminifera and the appearance of the first Danian species, signal a reliable marker horizon for the Cretaceous–Paleogene boundary.Fossil faunal and floral assemblages, both marine and terrestrial, make for distinctive marker horizons. Some marker units are distinctive by virtue of their magnetic qualities. The Water Tower Slates, forming part of the Hospital Hill Series in the Witwatersrand Basin, include a fine-grained ferruginous quartzite which is particularly magnetic. From the same series a ripple-marked quartzite and a speckled bed are used as marker horizons.On a much smaller time scale, marker horizons may be created by sedimentologists and limnologists in order to measure deposition and erosion rates in a marsh or pond environment. The materials used for such an artificial horizon are chosen for their visibility and stability and may be brick dust, grog, sand, kaolin, glitter or feldspar clay.".
- Marker_horizon thumbnail Icelandic_tephra.JPG?width=300.
- Marker_horizon wikiPageExternalLink v=onepage&q=Marker%20horizons%20stratigraphic%20units&f=false.
- Marker_horizon wikiPageID "29002325".
- Marker_horizon wikiPageLength "3936".
- Marker_horizon wikiPageOutDegree "28".
- Marker_horizon wikiPageRevisionID "683254967".
- Marker_horizon wikiPageWikiLink Archaeology.
- Marker_horizon wikiPageWikiLink Category:Geochronology.
- Marker_horizon wikiPageWikiLink Category:Stratigraphy.
- Marker_horizon wikiPageWikiLink Chicxulub_crater.
- Marker_horizon wikiPageWikiLink Conodont.
- Marker_horizon wikiPageWikiLink Cretaceous–Paleogene_boundary.
- Marker_horizon wikiPageWikiLink Danian.
- Marker_horizon wikiPageWikiLink Extinction_event.
- Marker_horizon wikiPageWikiLink Faunal_assemblage.
- Marker_horizon wikiPageWikiLink Foraminifera.
- Marker_horizon wikiPageWikiLink Fossil.
- Marker_horizon wikiPageWikiLink Iridium.
- Marker_horizon wikiPageWikiLink Iridium_anomaly.
- Marker_horizon wikiPageWikiLink Iron_oxide.
- Marker_horizon wikiPageWikiLink Isochronous.
- Marker_horizon wikiPageWikiLink Limnology.
- Marker_horizon wikiPageWikiLink Meteoroid.
- Marker_horizon wikiPageWikiLink Paleomagnetism.
- Marker_horizon wikiPageWikiLink Palynology.
- Marker_horizon wikiPageWikiLink Quartzite.
- Marker_horizon wikiPageWikiLink Rock_magnetism.
- Marker_horizon wikiPageWikiLink Sedimentology.
- Marker_horizon wikiPageWikiLink Stratigraphy.
- Marker_horizon wikiPageWikiLink Stratum.
- Marker_horizon wikiPageWikiLink Tephra.
- Marker_horizon wikiPageWikiLink Volcano.
- Marker_horizon wikiPageWikiLink Witwatersrand_Basin.
- Marker_horizon wikiPageWikiLink File:Icelandic_tephra.JPG.
- Marker_horizon wikiPageWikiLinkText "Marker horizon".
- Marker_horizon wikiPageWikiLinkText "correlation".
- Marker_horizon wikiPageWikiLinkText "marker bed".
- Marker_horizon wikiPageWikiLinkText "marker horizon".
- Marker_horizon wikiPageWikiLinkText "stratigraphic marker".
- Marker_horizon wikiPageUsesTemplate Template:Reflist.
- Marker_horizon subject Category:Geochronology.
- Marker_horizon subject Category:Stratigraphy.
- Marker_horizon hypernym Units.
- Marker_horizon type MilitaryUnit.
- Marker_horizon type Subfield.
- Marker_horizon comment "Marker horizons or chronohorizons or marker beds are stratigraphic units of the same age and of such distinctive composition and appearance, that, despite their presence in separate geographic locations, there is no doubt about their being of equivalent age (isochronous) and of common origin.".
- Marker_horizon label "Marker horizon".
- Marker_horizon sameAs Q6770636.
- Marker_horizon sameAs m.0dgmzk5.
- Marker_horizon sameAs Q6770636.
- Marker_horizon wasDerivedFrom Marker_horizon?oldid=683254967.
- Marker_horizon depiction Icelandic_tephra.JPG.
- Marker_horizon isPrimaryTopicOf Marker_horizon.