Editing Neogene (section)

==Disagreements==
The Neogene traditionally ended at the end of the Pliocene Epoch, just before the older definition of the beginning of the [[Quaternary]] Period; many time scales show this division.

However, there was a movement amongst geologists (particularly [[marine geologist]]s) to also include ongoing geological time (Quaternary) in the Neogene, while others (particularly terrestrial geologists) insist the Quaternary to be a separate period of distinctly different record. The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries is due to the comparatively fine divisibility of time units as time approaches the present, and due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and to reflect many more environments than the older geological record.<ref name="tucker-2001">{{cite book |last1=Tucker |first1=M.E. |author-link1=Tucker, M. E. |title=Sedimentary petrology : an introduction to the origin of sedimentary rocks |date=2001 |publisher=Blackwell Science |location=Osney Nead, Oxford, UK |isbn=978-0-632-05735-1 |edition=3rd |language=en}}</ref> By dividing the [[Cenozoic]] Era into three (arguably two) periods ([[Paleogene]], Neogene, [[Quaternary]]) instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic Eras.

The [[International Commission on Stratigraphy]] (ICS) once proposed that the Quaternary be considered a sub-era (sub-erathem) of the Neogene, with a beginning date of 2.58 Ma, namely the start of the [[Gelasian|Gelasian Stage]].  In the 2004 proposal of the ICS, the Neogene would have consisted of the [[Miocene]] and  [[Pliocene]] Epochs.<ref>Lourens, L., Hilgen, F., Shackleton, N.J., Laskar, J., Wilson, D., (2004) "The Neogene Period". In: Gradstein, F., Ogg, J., Smith, A.G. (Eds.), ''Geologic Time Scale'', Cambridge University Press, Cambridge.</ref> The [[International Union for Quaternary Research]] (INQUA) counterproposed that the Neogene and the Pliocene end at 2.58 Ma, that the Gelasian be transferred to the Pleistocene, and the Quaternary be recognized as the third period in the Cenozoic, citing  key changes in Earth's climate, oceans, and biota that occurred 2.58 Ma and its correspondence to the [[Gauss-Matuyama reversal|Gauss-Matuyama magnetostratigraphic boundary]].<ref name="INQUA-16-1">[http://www.inqua.tcd.ie/documents/QP%2016-1.pdf Clague, John ''et al.''  (2006) "Open Letter by INQUA Executive Committee"] {{webarchive|url=https://web.archive.org/web/20060923053134/http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |date=2006-09-23 }} ''Quaternary Perspective, the INQUA Newsletter'' International Union for Quaternary Research 16(1)</ref><ref>{{cite journal |last1=Clague |first1=John  |display-authors=etal|title=Open Letter by INQUA Executive Committee |journal=Quaternary Perspective, the INQUA Newsletter |date=2006 |volume=16 |issue=1 |url=http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |access-date=2006-09-23 |doi=10.1016/j.quaint.2006.06.001|archive-url=https://web.archive.org/web/20060923053134/http://www.inqua.tcd.ie/documents/QP%2016-1.pdf |archive-date=2006-09-23|publisher=International Union for Quaternary Research|issn=1040-6182|pages=158–159}}</ref> In 2006 ICS and INQUA reached a compromise that made Quaternary a sub-era, subdividing Cenozoic into the old classical [[Tertiary]] and Quaternary, a compromise that was rejected by [[International Union of Geological Sciences]] because it split both Neogene and Pliocene in two.<ref>{{cite web|url=http://www.stratigraphy.org/report06.pdf|title=ICS: Consolidated Annual Report for 2006|website=Stratigraphy.org|access-date=15 June 2007}}</ref>

Following formal discussions at the 2008 International Geological Congress in Oslo, Norway,<ref>{{cite web|url=http://www.33igc.org/coco/LayoutPage.aspx|title=Geoparks and Geotourism – Field Excursion of South America|website=33igc.org|access-date=17 December 2017}}</ref> the ICS decided in May 2009 to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.58 Mya and including the Gelasian Age, which was formerly considered part of the Neogene Period and Pliocene Epoch.<ref name="ICS2009">{{cite web|url=http://www.quaternary.stratigraphy.org.uk/correlation/GSAchron09.jpg|title=See the 2009 version of the ICS geologic time scale|website=Quaternary.stratigraphy.org.uk|access-date=17 December 2017}}</ref> Thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya.