Request for discussion on whether to forward INQUA’s Position on
Quaternary directly to IUGS for possible acceptance
Background – Irreconcilable decisions and restrictions
(1) Quaternary begins at 2.6 Ma
In 2005, the joint INQUA-ICS Task Group unanimously recommended that the Quaternary
be established using the base of the current Gelasian Stage (ca. 2.6 Ma) of the upper Pliocene
Series. The ICS unanimously agreed with this recommendation in its 2005 meeting in Leuven –
from our summary report “Both the Task Group and the ICS members were in near-unanimous
agreement that the Quaternary, as currently used by INQUA and Quaternary research specialists,
should begin at the evidence of dramatic climatic and oceanographic change at 2.6 Ma. The
extensive evidence for this first major “Ice Age” with widespread expansion of ice sheets over the
northern continents is summarized in the Task Group report.”
(2) Pleistocene Series/Epoch GSSP is at Vrica with an age of about 1.8 Ma
The Pleistocene Series/Epoch was defined by Aguirre and Pasini (1985) with a GSSP at
Vrica (ca. 1.8 Ma) in the infamous document that left in limbo a status for a Quaternary or a
Calabrian stage. This base-Pleistocene GSSP underwent a lengthy review that was completed in
1998, with the INQUA-ICS working group and joint Neogene and Quaternary subcommissions
unable to reach a super-majority decision on any of the main issues. ICS was informed of the
majority (but not super-majority) recommendation to retain the current Pleistocene GSSP, but ICS
did not take a formal vote on this issue. The cover letter by Jürgen Remane to IUGS (Nov, 1998)
on retaining the base-Pleistocene emphasized that “its acceptance by Quaternary stratigraphers
remains uncertain.” This, indeed, has been the case.
(3) Quaternary must fit into a hierarchy
The dilemma was how to give this Quaternary a suitable chronostratigraphic rank. In this
regard, it is impossible to insert a Quaternary with its base at 2.6 Ma into the current late-Cenozoic
hierarchy.
From the ICS letter to IUGS of 25Sept2006: “Given that the base-Pleistocene GSSP is
fixed through the end of 2008 (in late Jan 1999, IUGS had re-ratified its placement at 1.8 Ma), and
that the Cenozoic has two ratified periods (Neogene and Paleogene), then one way to temporarily
accommodate the INQUA-definition of Quaternary was to display it and Tertiary as sub-eras (ICS
had a 70% vote for this option last year).” IUGS rejected ICS’s request for this usage of
Quaternary-Tertiary, and was quite explicit that no lower-rank unit can span the boundary between
higher-rank units. In addition, “restraint is recommended in creating new orders of
chronostratigraphic units, as sub-erathem, sub-system, sub-series and sub-stage.”
(4) Ten-year moratorium on Pleistocene expires at end-January 2009
The GSSP guidelines contain a provision for maintaining decisions for a minimum of ten
years, unless there are extraordinary circumstances. In this regard, the ICS guidelines (Remane et
al., 1996) states "A GSSP or GSSA can be changed if a strong demand arises out of research
subsequent to its establishment. But in the meantime it will give a stable point of reference.
Normally, this stability should be maintained and the practical value of the boundary definition
tested for a minimum period of ten years." To some of us, this gives enough flexibility to change a
boundary (base of Pleistocene) because of strong demand arising out of research by the Quaternary
community.
The Plio-Pleistocene working group situation and the joint vote of Quaternary and Neogene
subcommission were presented to IUGS in late January 1999 by Jürgen Remane (see Appendix).
The IUGS resolved to support the existing Plio-Pleistocene boundary.
In their deliberations (see Appendix), there is no statement that this is should be the base of
the Quaternary. Zhang Hongren, President of IUGS, has also stated that “The current IUGS EC has
not made any decision on the preferred definition/ranking of the Quaternary.” (6 Mar 2007 letter to
John Clague, President of INQUA). Therefore, we are not currently bound by any pre-existing
decision and associated moratorium on the Quaternary, but only on the base-Pleistocene taken in
1999. This opens the window on a possible solution, as will be explained below.
(5) Quaternary must be resolved by August 2008
IUGS has requested that ICS resolve Quaternary for final ratification by the IGC in August
2008. Their recent letter to ICS is quite explicit that “it is necessary to reach as soon as possible
an international consensus on the Quaternary problem that has to be ratified during the 2008 IGC.”
IUGS has not commented on the “Tertiary”, nor on the requested 2.6 myr time-span of the
Quaternary. Only the Quaternary is under consideration, and it must fit into the hierarchy.
(6) ICS must include INQUA’s opinion
Quoting the International Union for Quaternary Research (INQUA) letter to ICS:
The unanimous position of the INQUA Executive Committee is the following:
1) The Quaternary must be a full formal chronostratigraphic unit, the
appropriate status for which is the Period (or System).
2) The base of the Quaternary should be placed at the current base of GSSP
Gelasian Stage (currently in the Pliocene) at MIS 103.
3) The base of the Pleistocene should be lowered to 2.6 Ma to coincide with that
of the Quaternary Period/System boundary.
[“MIS 103” = Marine Isotope Stage 103. NOTE: Because Phanerozoic geologic boundaries are not defined
by numerical ages, the concluding statement should be worded that “the base of the Pleistocene should be lowered to
coincide with the Quaternary System/Period boundary, which is calibrated to an age of 2.6 Ma”.]
The opening page of INQUA’s website begins “The Quaternary Period spans the last 2.6
million years of the Earth's history.”
*******************************************
We would like ICS members to consider the following set of compromises to resolve this
issue. It will require suspension of at least one operating guideline and will also require making
some recommendations without convening additional task groups. No solution will please
everyone, but perhaps this one will be acceptable to the vast majority of the people who are actively
involved.
Suggested package:
(1) Forward the INQUA position directly to IUGS
ICS would forward the INQUA position to IUGS for immediate consideration as a package,
and recommend that the Quaternary be established prior to the INQUA Congress in August
2007. This seems the only way to adequately satisfy the mandate that we establish a
Quaternary both through dialog with INQUA and prior the 2008 International Geological
Congress.
(2) Pleistocene would be extended to enable a Quaternary System/Period
IUGS would be requested to reverse their January 1999 decision, and include the Gelasian
stage into the Pleistocene. No new GSSP is being created; rather, the boundary of the higher
chronostratigraphic unit (Pleistocene Series) is being moved to the GSSP of a different
stage. The Quaternary would be formally ranked as a Period with its base synchronous with
the base of this Pleistocene. The change is being made so that the Quaternary is defineid in
the manner that it is being used by the majority of its active workers (INQUA), which is the
audience with direct interest in its definition and consistent usage of it. In 1997-98, neither
the INQUA-ICS working group nor the joint Quaternary-Neogene subcommission votes on
these issues could reach a super-majority (67%) agreement on scientific grounds. However,
in this case, the main argument is the desire to attain a satisfactory hierarchy that can
accommodate the Quaternary, rather than a scientific rationale as to why the current marinebased Pleistocene is unsuitable. INQUA’s President, John Clague, has indicated that he will
send a letter to IUGS supporting this unusual procedural action to revisit their 1999 decision
and accept INQUA’s position on the definition, rank and appropriate hierarchy for the
Quaternary.
Suggested additional clarifications:
(3) Tertiary has no official rank
The Neogene and Paleogene would remain as Periods/Systems. The Gelasian/Piacenzian
stage boundary (revised Pleistocene/Pliocene boundary) would be the Quaternary/Neogene
system boundary. This clarification should be included in the IUGS decision, otherwise we
will be immediately asked by many groups to consider ‘demoting” the Neogene and
Paleogene to become sub-periods. The Tertiary would remain informal as a “super-period”
equivalent to the Neogene-Paleogene.
(4) Gelasian Stage remains intact; Pleistocene has stage-level divisions
The Gelasian Stage would remain intact, but the Pleistocene Series would be extended
downwards to include it. This also implies that the Pleistocene would be subdivided into
named-stages.
(5) Vrica GSSP is retained, but as a Stage Boundary
The Vrica GSSP is not being altered or abandoned. This GSSP will continue to define the
top of the Gelasian and the base of the Calabrian Stage. The Calabrian, like the Quaternary,
was left in limbo by the 1985 base-Pleistocene GSSP document, but is often shown on timescale charts and is proposed as a regional stage (Cita et al., 2006).
*******************************************
Before preparing a formal ICS ballot on submitting the above package or other set of
recommendations to an ICS vote, we invite open discussion among all ICS members. In addition,
comments from other people are welcome and should be circulated to everyone.
The Appendices to this document include selected readings, a copy of the 1999 IUGS
minutes that re-ratified the Pleistocene GSSP, and other information.
The Gelasian GSSP document is available from Episodes at:
http://www.episodes.org/backissues/212/82-87%20rio.pdf . The Gelasian GSSP is placed at the
base of a marl unit that corresponds to inter-glacial MIS 103 (and the associated astronomical cycle)
that is close to a major paleomagnetic reversal.
Based on the recommendations and suggestions that are received during the next month or
so, we will compose a formal ballot for ICS voting. We will strive to prepare a package for ICS
consideration that can be submitted to IUGS that both meets their requirements and is satisfactory
with the majority of Quaternary workers.
E-mail Address suite for circulating comments and recommendations:
Chair <felix.gradstein@nhm.uio.no>, ViceChair <scfinney@csulb.edu>, Secr <jogg@purdue.edu>, Quat
<plg1@cus.cam.ac.uk>, Neog <fhilgen@geo.uu.nl>, Paleog <emolina@posta.unizar.es>, Cret
<Isabella.Premoli@unimi.it>, Jur <NICOL.MORTON@wanadoo.fr>, Tri <morchard@nrcan.gc.ca>, Perm
<charles.Henderson@ucalgary.ca>, Carb <philip-heckel@uiowa.edu>, Dev <rbecker@uni-muenster.de>,
Sil <jyrong@nigpas.ac.cn>, <jiayu_rong@yahoo.com>, Ordov <xu1936@yahoo.com>, Camb
<scpeng@nigpas.ac.cn>, Ediac <jgehling@ozemail.com.au>, PreCamb <WBleeker@NRCan.gc.ca>,
StratClass <maria.cita@unimi.it>
If you wish copies of the past Quaternary-related documents by the 2005 joint Task Group,
INQUA’s extensive survey (over 100 letters were received, including several national
organizations), or other documents, please notify Jim Ogg, the ICS secretary-general.
APPENDIX 1
Selected Bibliography – A few review articles on Quaternary, Neogene, Pleistocene, Gelasian
and Tertiary. There are many others, but this subset contains different viewpoints and
historical/scientific perspectives.
Aguirre, E., Pasini, G., 1985. The Pliocene–Pleistocene boundary. Episodes, 8: 116–120.
Aubry, M-P., Berggren, W.A., Van Couvering, J., McGowran, B., Pillans, B., and Hilgen, F., 2005.
Quaternary: status, rank, definition, survival. Episodes, 28: 118-120.
Balco, G., Rovey, C.W., II, and Stone, J.O.H., 2005. The first glacial maximum in North America.
Science, 307: 222.
Berggen, W.A., 1998. The Cenozoic Era: Lyellian (chrono) stratigraphy and nomenclatural reform
at the millennium. In: Lyell: the past is the key to the Present (edited by Blundell, D.J. &
Scott, A.C.) Geological Society, London, Special Publication 143, 11-132.
Bowen, D.Q., and Gibbard, P.L., 2007. The Quaternary is here to stay. Journal of Quaternary
Science, 22: 3-8.
Cita, M.B., Capraro, L., Ciaranfi, N., Di Stephano, E., Marino, M., Rio, D., Sprovieri, R. and Vai,
G.B., 2006. Calabrian and Ionian: A proposal for the definition of Mediterranean stages for
the Lower and Middle Pleistocene. Episodes, 29: 107-113.
Gibbard, P.L., et al (12 co-authors), 2005. What status for the Quaternary? Boreas, 34: 1-6.
Gignoux, M., 1910. Sur la classification du Pliociene et du Quaternaire dans Italie du Sud.
Comptes Rendus de l’Academie des Sciences, Paris, 150: 841-844.
Gignoux, M., 1913. Les formations marines pliocènes et quaternaires de l'Italie du Sud et de la
Sicile. Université de Lyon, Annales, n.s., v. 1 (36), pp. 1-633.
Lourens, L., F. Hilgen, N.J. Shackleton, J. Laskar and D. Wilson, 2004. The Neogene Period. In:
Geologic Time Scale 2004 (coordinated by Gradstein, F.M., Ogg, J.G., and Smith, A.G.),
Cambridge University Press: pg. 409-440.
Ogg, J.G., 2004. Introduction to concepts and proposed standardization of the term Quaternary.
Episodes 27: 125-126.
Pillans, B., 2004. Proposal to redefine the Quaternary. Episodes 27: 127.
Pillans, B., and Naish, 2004. Defining the Quaternary. Quaternary Science Reviews, 23: 22712282.
Salvador, A., 2006. The Tertiary and Quaternary are here to stay. American Association of
Petroleum Geologists Bulletin, 90: 21-30.
Suguio, K., Sallun, A.E.M., Soares, E.A.A., 2005. Quaternary: “quo vadis”? Episodes, 28, 197–
200.
Van Couvering, J. A., 1997. The New Pleistocene. In: The Pleistocene boundary and the
beginning of the Quaternary (edited by J.A. Van Couvering), Cambridge: Cambridge
University Press, pp. i-vi.
Walsh, S.L., 2006. Hierarchical subdivision of the Cenozoic Era: A venerable solution, and a
critique of current proposals. Earth-Science Reviews, 78: 207-237.
APPENDIX 2
Extract from Minutes; 45th IUGS Executive Committee Meeting
Florence, Italy; January 26-30, 1999
4.b.7. Commission on Stratigraphy (ICS)
Plio/Pleistocene boundary (PPB): Confusion about the position of the PPB has been steadily
growing in the last years. Since 1992, a certain number of Quaternary stratigraphers requested a
lowering of the boundary from 1.8 to 2.5 Ma. Arguments brought forward in favor of a change
were, however, often misleading and did not take into account the existence of formal international
agreements. The PPB was formally defined by a GSSP in 1984, agreed upon by IUGS and INQUA.
A scientifically substantiated demand which could have been voted upon in accordance with the
statutory procedures of ICS was never presented. An independent Ad-hoc Committee instituted by
IUGS met in spring 1997, but did not reach a conclusion. The problem was referred back to ICS,
which was invited to organize a joint vote of the Neogene and the Quaternary Subcommission to
decide about the definite position of the PPB. But one year later no formal submission was yet
received by the ICS Bureau, while lobbying in favor of a change of the PPB outside the commission
continued. Therefore the ICS Bureau decided on the above-mentioned meeting to set a deadline for
the receipt of a formal submission. The deadline passed, any further demand for a change of the
boundary would be considered as nil. In agreement with the President of IUGS, the deadline was
fixed at August 31, 1998. The vote is now under way, but there are still considerable difficulties to
be overcome.
J. Remane (ICS Chairman) gave first some additional comments to the above summary of the
Plio- Pleistocene Boundary problem and asked the Executive Committee to approve the result of a
joint vote of the Subcommission on Quaternary Stratigraphy (SQS) and the Subcommission on
Neogene Stratigraphy (SNS). Both Subcommissions had voted to reject the demand to lower the
Plio-Pleistocene boundary. Remane indicated that both Subcommissions had agreed on a ballot, but
there had been some arithmetic difficulties since some members are members of both groups.
There had been an active debate on the voting procedure. The Committee discussed the proposal to
lower the boundary and the result of the vote of the SQS and SNS.
The Committee APPROVED, with one abstention, the Subcommissions' vote which supported
the existing Plio-Pleistocene boundary, formally defined by a GSSP at Vrica in 1984.
APPENDIX 3
Recommendations by the
Quaternary Task Group
jointly of the
International Commission on Stratigraphy (ICS, of the International Union of Geological
Sciences, IUGS)
and of the International Union for Quaternary Research (INQUA)
Summary of recommendations
The Quaternary Task Group recommends that the Quaternary be:
(1) An officially ratified geochronologic/chronostratigraphic unit of the international
geologic time scale,
(2) Defined as the interval from the GSSP base of the Gelasian Stage (approximately 2.59
Ma) of the late Pliocene Epoch to the Present, and
(3) Assigned the geochronologic rank of Period or Sub-Era within the Cenozoic Era. [A
majority (6 of 8) considered Period acceptable, and a lesser majority (5 of 8) found
Sub-Era to be acceptable.]
The Task Group examined what the term Quaternary means to the geologic community.
The term is synonymous with the time span and stratigraphic record of major climatic oscillations
and Northern Hemisphere glacial episodes. Even though there was a general progressive climatic
cooling through the Neogene, both the terrestrial record of glacial extent and loess and the marine
record of ice-rafted debris and stratification show a clear onset of major glacial episodes beginning
at approximately 2.7 to 2.6 Ma (e.g., review by Pillans and Naish, 2004). The earliest record of
Laurentide ice-sheet expansion as far south as central Missouri, equivalent in scope to any later
North American glaciations, is the Atlanta glacial till of 2.4 Ma (Balco et al., 2005). This time span
also conveniently encompasses the development of humans as toolmakers and the evolution of the
genus Homo.
On the other hand, several studies have documented an abrupt cooling of climate and
dramatic paleoceanographic changes accompanying Marine Isotope Stage 110, and this level may
mark the onset of environmental conditions that are usually associated with the Quaternary. Some
of these indicators at MIS 110 (~2.73 Ma) include:
(a) sudden appearance of significant ice-rafted debris in northern high-latitude oceans [Nature,
307 (1984): pg.620; ODP Leg 145 (1995)],
(b) onset of stratification in both northern and southern high latitudes [Nature, 401 (1999):
pg.779, and Nature, 428 (2004): pg.59],
(c) Chinese loess and other climate proxies [diagrammed in Quat. Sci. Rev.; Pillans & Naish,
2004],
(d) the first influx of the planktonic foraminifer Neogloboquadrina atlantica into the
Mediterranean is associated with MIS110 (“Marine Isotope Stage” 110) [F. Hilgen,
written response to the Quaternary ‘Task Force’ working group Ballot No. 1]
(e) and coincides with a glacial-induced sea-level drop during Northern Hemisphere ice-sheet
growth and final closure of Isthmus of Panama allowing land-mammal exchange
[reviewed in Nature, 383 (1998): 674].
Persuasive arguments for an approximately 2.6 Ma age include:
(a) considerations for ease in global correlation based on the Gauss/Matuyama magnetic
reversal (base of Chron C2Ar; 2.581 Ma), and
(b) the ability to tie to an established GSSP. The GSSP-defined base of the Gelasian Stage is
in the peak of an extreme interglacial producing sapropel A5 (the Nicola key bed;
Marine Isotope Stage 103) at 2.588 Ma.
(c) the level is shortly after
Informal polling of INQUA (International Union for Quaternary Research) members,
comments by the majority of e-mails to ICS-INQUA on the Quaternary, the general Quaternary
usage problems that had led to the 1998 re-examination of the base-Pleistocene, all published
articles that relied on geologic arguments (especially terrestrial), and other external input
collectively support the view that the Quaternary concept spans the past 2.6 million years. Voting
of the Task Group was unanimous on this definition.
APPENDIX 4
Background to the status of Quaternary – Concept, and why it
currently lacks placement in the chronostratigraphic scale
[From Quaternary Task Group report]
[Compiled by J. Ogg, with assistance of J. Van Couvering]
The Cenozoic Era currently has two ratified Periods – the Neogene (Holocene, Pleistocene,
Pliocene, and Miocene epochs, or approximately 0.0 to 23.0 Ma) and the Paleogene (Oligocene,
Eocene, and Paleocene epochs, or approximately 23.0 to 65.5 Ma). However, the term
“Quaternary” has a long tradition of usage among all areas of geosciences and public education.
“Most people relate the Quaternary to the youngest period of geological history that is
characterized by strong oscillations of the climate and that towards its end culminates in a
series of major glaciations. Signs of early glaciations in the Northern Hemisphere are
known from about 2.6 Ma. As a result, rapid worldwide changes in climate and sea level
have been recorded. This, in turn, speeded up many terrestrial geological processes and
caused rapid global shifts of climate and vegetation zones. In fact, the dynamics of the
ecosystems at the Earth’s surface changed spectacularly. The most densely populated
areas in Europe (and elsewhere) are the alluvial plains and lowland areas that have been
formed during the Quaternary.” [excerpt from letter from Netherlands Institute of Applied
Geosciences, National Geological Survey]
A long-standing hurdle for including the Quaternary in the international chronostratigraphic
scale, is that, even though Quaternary is in widespread usage, it has lacked a consistent definition
among researchers and national geologic surveys. For example, the above letter from the
Netherlands National Geological Survey refers to 2.6 Ma, and this is the span of the Quaternary
favored by most INQUA members and the majority of letter writers to ICS-INQUA on this issue.
However, other organizations (e.g., the North American Commission on Stratigraphic
Nomenclature) equate Quaternary with the pair of Holocene and Pleistocene epochs, and therefore
assign a basal age of 1.8 Ma. Partly because of such disagreements on its appropriate age span and
associated formal definition, the Quaternary has never been ratified as a chronostratigraphic
division within the international geologic time scale, nor assigned a chronostratigraphic rank.
Therefore, the joint INQUA-ICS Quaternary Task Group was “charged with
the single task of defining the Quaternary in a stratigraphic sense. If the task
group recommends definition in a formal chronostratigraphic sense, its
proposal will go through the standard ICS consultation, voting, and ratification
procedures.”
In a nutshell, today’s debate reflects an unsuccessful attempt to marry two independent
concepts: (1) a marine concept of “Pleistocene”, which was characterized by Sir Charles Lyell in
1833 for sediments with more than 90% of modern species, and revised by later workers in the
Mediterranean region to indicate regional influxes of cold-water mollusks into Neogene sediments,
and (2) a terrestrial concept of “Quaternary”, with mammal-rich Villafranchian deposits in Italy
and glacial records elsewhere in high latitudes. Authoritative recent papers on the century-long
debate on the definition, onset and stratigraphic relationships of the Quaternary and Pleistocene are
Van Couvering (1997), Berggren (1998), Lourens et al. (2004), Ogg (2004), Pillans (2004), Pillans
and Naish (2004), Gibbard et al. (2005), and Aubry et al. (2005). The current varied viewpoints and
historical perspectives espoused by these publications illustrate that disagreements still exist. We
will briefly summarize four major milestones that led to the current situation.
1948: International Geological Congress solves one problem, but creates another:
According to the recommendation of its special Commission, the 1948 London Congress
voted to locate the Pliocene-Pleistocene boundary at the base of the Calabrian Stage in southern
Italy, as defined by Gignoux (1910, 1913). By designating a physical reference point or “golden
spike” the Commission ended a century of fruitless debate over which conceptual definition of
Pleistocene should prevail -- marine, continental, anthropological, and not to mention customary
regional preferences. Even so, the proposal had to survive a potentially crippling concession to
vertebrate paleontologists on the Commission, in which “to remove existing ambiguities” the base
of the Pleistocene was also made equivalent to the Villafranchian “stage” (i.e., mammal age) in
continental sequences. As it proved, there were problems with both sides of this definition, in that
the “typical” Calabrian sections described by Gignoux were incomplete exposures of shallow-water
strata in which the basal transition could not be studied, and in that Villafranchian mammal faunas
extend well into pre-Calabrian levels. In the event, Gignoux’ basic concept for the Calabrian, as a
unit beginning with the “horizon of first indication of climate deterioration” in marine faunas,
became the governing criterion, and after several false starts a GSSP was finally proposed in deepwater Calabrian strata at Vrica, Calabria.
However, a more fundamental problem was left to complicate the situation for later
generations, in that the Congress did not clarify the rank-relationship, within the Italian upper
Cenozoic between the Pleistocene, as newly established in a physical reference point, and the
Quaternary, aside from parenthetical references to a “Tertiary-Quaternary” boundary as a time
equivalent entity.
Recommendations of Commission appointed to advise on the definition of the PliocenePleistocene boundary; 1 Sept 1948:
The Council of the Congress [=International Geological Congress] unanimously accepted
the recommendations of the Commission [appointed to advise on the definition of the PliocenePleistocene boundary]:
1. The Commission considers that it is necessary to select a type-area where the
Pliocene-Pleistocene (Tertiary-Quaternary) boundary can be drawn in accordance with
stratigraphical principles.
2. The Pliocene-Pleistocene (Tertiary-Quaternary) boundary should be based on
changes in marine faunas, especially in the classic area of marine sedimentation in Italy.
3. The Commission recommends that, in order to remove existing ambiguities, the
lower Pleistocene should include as its basal member in the type-area the Calabrian
formation (marine) together with its terrestrial (continental) equivalent, the Villafranchian.
4. The Commission notes that, according to evidence given, the usage would place
the boundary at the horizon of the first indication of climate deterioration in the Italian
Neogene succession.
(King & Oakley, 29 January 1949, Nature, 163: 186)
1984: Ratification of the Pleistocene-GSSP leaves “Quaternary” without a chronostratigraphic
rank:
The decision by the joint INQUA-ICS working group to assign the GSSP at Vrica in Sicily
for the base of the Pleistocene near the top of the Olduvai subchron (1.8 Ma) was ratified by IUGS
in 1984. This Pleistocene-Pliocene epoch-boundary working group had specifically omitted any
indication that the base of the Quaternary concept would coincide with the base of the Pleistocene;
indeed, the only mention of “Quaternary” is in the context of a concluding statement that explicitly
leaves it without status!
“The subject of defining the boundary between the Pliocene and Pleistocene was
isolated from other more or less related problems, such as the pending definition of the
Calabrian, and the status of the Quaternary within the chronostratigraphic scale.”
-- E. Aguirre and G. Pasini (1985, The Pliocene-Pleistocene Boundary. Episodes 8: 116120. = official publication of the base-Pleistocene GSSP decision by the special joint
INQUA-ICS working group)
As a result, the definition of the Quaternary has been left in limbo for 20 years.
Contributing to this indecision was the problem that the traditional Quaternary concept, as a time of
perceptible “deterioration” in continental environments (i.e., increase in the amplitude of global
climate cycles, continental glaciers covering ever more territory during climatic lows, and the
progressive adaptation of continental biotas to seasonal change, as in the Villafranchian mammal
faunas) was NOT explicitly incorporated into the concept of the Pleistocene GSSP.
After the Pleistocene GSSP was ratified, the term Quaternary developed a split personality.
On the one side, some national geological time scales displayed Quaternary as a period-level
division equivalent to the Holocene and Pleistocene epochs (hence, 1.8 Ma at the base). Whereas
on the other side, most Quaternary researchers and some other geologic surveys continued to equate
Quaternary with the earliest clear evidence of “deterioration” (glacial advances in mountain areas,
development of Villafranchian fauna, deposition of loess in China) at c. 2.6 Ma). This conflict in
usage between “on-paper equivalence” versus “actual geologic concept” reached a crescendo during
the 1990’s, when Quaternary specialists demanded that the “artificial” base of the Pleistocene be
lowered to accommodate the “true” Quaternary.
1998: Base-Pleistocene re-ratified as 1.8 Ma; but common base-Quaternary usage continues as 2.6
Ma
In 1998, another joint ICS-INQUA working group debated lowering the base-Pleistocene to
about 2.6 Ma (and moving the GSSP to another geographic location). The Vrica GSSP was upheld
by a slim majority (60%). Again, as in 1983, the official voting documents did not imply that this
base-Pleistocene GSSP would also define “base-Quaternary”. Indeed, from the documentation that
accompanied the submission of the voting results to IUGS, it is apparent that a number of members
of INQUA did not want a base-Quaternary defined as at the ratified and re-confirmed basePleistocene level.
“The demand to lower the Plio-Pleistocene boundary (to 2.5 Ma), abolishing its
formal definition through the Vrica GSSP, is thus rejected. … Despite the clear result of
the vote, its acceptance by Quaternary stratigraphers remains uncertain. In some cases,
the existing (Pleistocene) boundary was simply ignored and the base of the Quaternary
placed at 2.5 Ma.”
-- ICS report to IUGS (Dec, 1998) on joint vote by 34 members of working group (59% to retain,
38% to lower)
The re-ratification of the Pleistocene GSSP in 1998 still left the term Quaternary formally
undefined under IUGS guidelines, without chronostratigraphic rank, and not explicitly equated with
the Pleistocene.
At the 2000 International Geologic Congress in Rio de Janeiro, a hybrid UNESCO-CGMWIUGS-ICS time scale chart was distributed to participants, which displayed the status of GSSP
ratifications. This chart showed a “Quaternary” as a period truncating the Neogene at the base of
the Pleistocene. However, the insertion of a Quaternary was one of several contentious issues and
compromises during preparation of this joint UNESCO-IUGS chart (Jürgen Remane, pers.
communication to Jim Ogg, July 2000), and the final product from UNESCO was altered
considerably from the initial draft prepared by ICS. Therefore, for clarity, the ICS decided to
remove aspects from UNESCO’s groups that had caused unnecessary criticism (e.g., abbreviation
system for stages-period), and publish full documentation of GSSPs and time-scale status in
literature (Episodes, etc.) and on the ICS website. The lack of ratification or agreement on
Quaternary was indicated; and the Cenozoic on the charts and tables was divided into its two
ratified periods – Neogene and Paleogene.