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The 'Subcommission for Tertiary Stratigraphy' was recently renamed as 'Subcommission for Paleogene and Neogene Stratigraphy'.

During the first decennia of its existence, the main task of the subcommission was the elaboration of the Cenozoic lithostratigraphic framework of Belgium. A detailed lithostratigraphic scale was nonexistent before, and was a prerequisite for the revision of the geological maps of Belgium. It is however well know that a definite lithostratigraphic scale can only be realised once the mapping is completed. The present task of the subcommission is now to fine-tune and stabilise the lithostratigraphic scale. A robust lithostratigraphic scale is furthermore a necessity for further stratigraphical studies in the field of biostratigraphy, chronostratigraphy, seismic and sequence stratigraphy, etc.

The term 'Tertiary' in stratigraphic nomenclature

A concise status questionis anno 2014

The term Tertiary has been omitted from the  IUGS stratigraphic charts at least since  1989 as shown in the chart compiled by Cowie and Bassett  (1989 ). In the notes accompanying this 1989 chart  (note 6),  it is stated that ICS  has, since 1976, divided  the Cenozoic  Erathem into Paleogene, Neogene and  Quaternary Systems.  In the same note it is further stated that the term Tertiary is a useful informal term to include both the Paleogene and the Neogene.  Also as today , the term Tertiary is omitted from  the ICS standard chronostratigraphic chart on their website

Undoubtedly the abandonment of the term Tertiary  was the consequence of subdividing the Phanerozoic Eonothem/Eon in three logical parts: the Paleozoic, Mesozoic and Cenozoic Erathems/Era’s  and no longer in the formerly used terminology  Primary, Secondary, Tertiary and Quaternary.  The same logic led to the abandonment of the term Quaternary in the Geological Time Scale 2004 edited under the auspices of ICS (see e.g. Gradstein et al. , 2004) to be reintroduced  as ‘under discussion’ in the next edition of the GTS ,2008 (Ogg et al., 2008).

In a volume devoted to Charles Lyell’s work, Berggren (1998) published a paper on the chronostratigraphic nomenclature of the Cenozoic Era and concluded that ‘ Tertiary and Quaternary should be abandoned, relicts of now outmoded, and inappropriate, pre-Lyellian stratigraphy’.

Nevertheless, the influential stratigraphic charts published by Haq et al. (1987) and  Hardenbol et al. (1998) did continue to use the term Tertiary together with the  Quaternary as Systems/Periods, and the Paleogene and Neogene as subdivisions of the Tertiary (Haq et al., 1987) or the Cenozoic (Hardenbol et al., 1998).

Also on several national charts, like the  Geological Time Scale of the Geological Society of America, the Tertiary (and Quaternary) continued to be explicitly figured as a period with Paleogene and Neogene subdivisions.  The USGS Geological  Names Committee (2009) continued to use the term Tertiary as a period/System with Paleogene and Neogene as Subperiods/Subsystems ,  ‘until a decision is made on the subdivisions of the Cenozoic’.

The term Tertiary has indeed continued to be used by geologists e.g. in the practice of mapping  or whenever the grouping of strata between Cretaceous and Quaternary did not need further  distinction between Paleogene and Neogene. It can be expected that  also in the future the term Tertiary will be sufficiently accurate for convenient use in many situations.

This raises the question whether  Tertiary should be reinstalled as an official  System/Period name with the Paleogene and Neogene  as sub-systems/sub-periods.

Not surprisingly therefore that such proposal to formally define the Tertiary period between the base Danian and the base Quaternary with Paleogene and Neogene as subperiods, was published in the Special Issue of Episodes on the Quaternary Period/System (Head et al., 2008). Indeed as the Quaternary now has been defined as a System/Period,  and  not as a Sub-Period, some logic in nomenclature can be invoked to consider the Tertiary as a Period of the same rank as Quaternary. One of the authors of this proposal, Amos Salvador, had published  already in 2006 a literature analysis demonstrating the continued widespread use of the term  Tertiary and strongly argued  for the formal recognition of it as a Period/System with Paleogene and Neogene as subperiods/subsystems (Salvador, 2006).  Also North American  geologists at the First International Conference on Stratigraphy  in 2013 in Lisbon  continue to  plead for revitalizing the Tertiary, based on common practice (Edwards et al., 2013). Aubry et al. (2005), in a Forum paper  in Episodes on the Quaternary issue proposed  Tertiary and  Quaternary as sub-era’s/suberathems of  the Cenozoic Era/Erathem  , noting ‘ that although there has been little opposition to removing Tertiary from modern time scales..strong interest has been expressed to resurrect it …’.

ICS however has continued to omit Tertiary from its charts even after the ratification of the Quaternary as a System/Period. Also in the GTS 2012, dedicated amongst others to ICS, the use of the term Tertiary is discouraged although it is recognized that the term still has widespread use (Gradstein etal.,2012  p. 856).

In 2012 the issue of the use of Tertiary as a formal or informal unit was examined by the U.K. Geological Society Stratigraphy Commission and summarized  in a well balanced and well written multi-authored short paper (Knox et al., 2012); the arguments for re-instatement of the Tertiary period are led by Robert Knox and the case for retaining Palaeogene and Neogene as periods and  Tertiary as an informal term  are led by  Paul Pearson.  

The term tertiary  has been  omitted from the ICS stratigraphic tables since 1989.  However the term continued to be used and defended internationally at many occasions.  Since the final definition in 2009 of the Quaternary as a Period starting at 2.59 Ma , with the Paleogene and Neogene as periods between the Cretaceous and the Quaternary,  voices have been raised again to reintroduce officially the term  tertiary as a period with Paleogene and Neogene as sub-periods.  However ICS has not taken any initiative to support this reintroduction. Therefore in 2012 the former Sub-commission Tertiary has changed its name to Subcommission Paleogene-Neogene to comply with ICS ( see reports ncs).”

Selected References

Aubry, M.-P., Berggren, W.A., Van Couvering, J., McGrowan, B., Pillans, B., Hilgen, F. , 2005. Quaternary: status, rank, definition , survival.  Episodes 28,2 p 118-120.

Berggren, W.A., 1998. The Cenozoic Era: Lyellian (chrono)stratigraphy and nomenclatural reform at the millennium.  In: Blundell,D.J. & Scott, A.C. (eds) Lyell: the Past is the key to the Present. Geological Society, London, Special Publications, 143, 111-132.

Cowie, J.W. and Bassett, M.G., 1989. Global Stratigraphic Chart.  Supplement to Episodes 12(2), June 1989.

Edwards, L.E., Orndorff, R.C., Head, M.J., Fensome, R.A. , 2013. It’s  Time to Revitalize the Tertiary.  Strati 2013 Ciências da terra Volume Especial VII, p 149.

Gradstein, F.M.,Ogg, J.G.,Smith, A.G.,Bleeker, W.,Lourens, L.J., 2004. A new geological Times Scale, with special reference to Precambrian and Neogene. Episodes 27,2, p 83-100.

Gradstein,F.M.,Ogg,J.G.,Schmitz, M.D., Ogg,G., 2012. The Geological Time Scale 2012. 1144pp (2 volumes). Elsevier.

Haq B.U., Hardenbol J. and Vail P.R., 1987.  Chronology of fluctuating sea levels since the Triassic.  Science 235, p.1156-1166.

Hardenbol,J.,Thierry,J., Farley,M.B., Jacquin, T., de Graciansky P.-C., Vail,P.R. 1998.  Mesozoic and Cenozoic sequence chronostratigraphic framework of European Basins.  In:   de Graciansky P.-C.,Hardenbol J.,Jacquin T.,Vail P.R. (eds.) Mesozoic and Cenozoic Sequence Stratigraphy of European Basins,  SEPM (Society for Sedimentary Geology) Special Publication 60 p 3-14 + 8charts

Head, M.J., Gibbard, P., Amos Salvador, 2008. The Tertiary: a proposal for its formal definition. Episodes,31,2, p 248-250.

International Commission of Stratigraphy (ICS)  of the International Union of Geologiccal Sciences (IUGS)   website

Knox, R.W.O’B., Pearson, P.N., Barry, T.L., Condon, D.J., Cope, J.C.W., Gale, A.S., Gibbard, P.L., Kerr, A.C., Hounslow, M.W., Powell, J.H., Rawson, P.F., Smith, A.G., Waters, C.N. , Zalasiewicz, J., 2012. Examining the case for the use of the Tertiary as a formal period or informal unit. Proceedings of the Geologists’ Association 123, p 390-393.

Ogg, J.G.,Ogg, G. and Gradstein, F.M., 2008. The concise Geologic Time Scale. Cambridge University Press.

Salvador, A., 2006. The Tertiary and the Quaternary are here to stay.  AAPG Bulletin, 90,1, p 21-30.

U.S.G.S.  Geological Names Committee, 2009.  Divisions of geologic time. Major chronostratigraphic and geochronologic units. Stratigraphy 6,2 p 90-92 ( can also be consulted on  the North American Commission on Stratigraphic Nomenclature  NACSN website )