[Aqualist] Status of the Quaternary

[Tim Barrows]

Status of the Quaternary
Your Opinion Sought

The International Commission on Stratigraphy 
(ICS), a body of the International Union of 
Geological Sciences (IUGS), is in the process of 
standardizing the Geological Time Scale, a task 
to be completed before the next International Geological Congress in 2008.

Quaternary task force
In 1985, with the placement of the base of the 
Pleistocene GSSP, “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: 
116-120). For various reasons, the "pending 
definition ... and status of the Quaternary" was 
never formally resolved, nor submitted to 
ICS/IUGS for consideration or ratification.

Following the International Geological Congress 
in 2004 in Florence, INQUA and ICS set up a task 
force to consider the issue. The task force was 
charged with making a recommendation, within one 
year, to ICS on the definition and possible rank 
of the Quaternary in the Geological Time Scale. 
It issued its report before a meeting of ICS in 
Leuven, Belgium, in September 2005. Its recommendation to ICS was as follows:

1) That the Quaternary should be recognized as a 
formal chronostratigraphic/ geochronological unit.
2) That the lower boundary of the Quaternary 
coincide with the base of the Gelasian Stage (2.6 
Ma) and thus be defined by the Gelasian GSSP.
3) That the Quaternary will have the rank of either:
         a. System/Period at the top of the 
Neogene System/Period, with its lower boundary 
marking the top of a shortened Neogene, or
         b. Sub-Erathem/Sub-Era correlative with 
the upper part of the Neogene System/Period

ICS decision
Following extended discussion at Leuven, the ICS 
voting membership unanimously voted, by a show of 
hands, that the Quaternary be recognized as a 
formal chronostratigraphic/geochronologic unit 
with a lower boundary coinciding with the base of 
the Gelasian Stage and defined by the Gelasian 
GSSP. The voting membership considered several 
options for the rank of the Quaternary, and voted 
on the options by a show of hands. Only one 
option received a majority: that the Quaternary 
have the rank of Sub-erathem/Sub-era. 
Subsequently, a written ballot was held on this 
single issue, i.e. whether or not the Quaternary 
should have the rank of Sub-Erathem/Sub-Era. The 
voting membership consisted of the executive 
officers of ICS and the chairs of the ICS 
subcommissions. The final vote on the Sub-Erathem/Sub-Era option was:

Yes             12 votes
No                5 votes
Abstain   1 vote

The result is that the lower boundary of the 
Quaternary would be defined at the base of the 
Gelasian Stage, at 2.6 Ma. Through an early 
polling of the Quaternary community, INQUA found 
that the vast majority of Quaternary scientists 
favour a 2.6 Ma boundary over the current 1.8 Ma 
one. A further result is that the Quaternary, 
although firmly formalized as a 
chronostratigraphic/geochronologic unit, would 
not be a System/Period above the Neogene. The 
Neogene would extend from the base of the Miocene to the present.

What now?
INQUA informed ICS, prior to the Leuven meeting, 
that it would consult the Quaternary community 
prior to deciding whether or not to support the 
new ICS position on the Quaternary. The INQUA 
Executive Committee is thus seeking your opinion. 
Please let us know whether the ICS proposal is 
acceptable to you or not? Below, I summarize this 
option and what the Executive Committee considers to be its pros and cons.

Definition of the Quaternary
The Quaternary is a Sub-Erathem/Sub-Era 
correlative with the upper part of the Neogene 
System/Period and with a lower boundary 
coincident with the base of the Gelasian Stage (2.6 Ma).
Pros:
                 ·  Quaternary is a formal 
chronostratigraphic/geochronologic unit, with a 
standardized definition and would be displayed on 
the international geological time scale.
         ·  Base of the Quaternary is pinned at 2.6 Ma.
         ·  ICS has accepted this option.
Cons:
                 ·  The Quaternary is not a Period/System.
         ·  The base of the Quaternary and that 
of the Pleistocene Epoch are not the same (the 
base of the Pleistocene remains at 1.8 Ma; the 
base of the Quaternary becomes 2.6 Ma).

Two other options have been discussed

Option 2:  The Quaternary is a Period/System 
above the Neogene, comprising the Pleistocene and 
Holocene epochs with a base at the base of the Gelasian Stage (2.6 Ma).
Option 3: Same as Option 2 except that the lower 
boundary of the Quaternary coincides with the 
base of the Pleistocene (1.8 Ma). Many Quaternary 
researchers consider this option the status quo.

ICS has said that it will not accept option 2, 
and it likely will not accept option 3. Thus, 
unless IUGS were to side with INQUA against its 
own commission, and could convince ICS to accept 
the Quaternary as a Period, the term will not 
have a standardized definition or formal ratified 
status on the Geological Time Scale.

What would be the consequences if the 
“Quaternary” was not formally included in the 
Geological Time Scale? The term would continue to 
be used, albeit informally, much as the 
“Precambrian” is used today. However, the stature 
of the “Quaternary” and our field of study would 
likely be diminished, with uncertain future 
consequences. Further, it might be difficult to 
have the Quaternary added to the Geological Time Scale at a later date.

Your opinion please
The INQUA Executive Committee asks that you give 
careful thought to this important issue and let 
John Clague (jclague at sfu.ca), know whether you 
consider the ICS proposal acceptable or 
unacceptable. Please take the time to respond, 
because the opinions of the Quaternary community 
will guide the Executive Committee in its 
response to ICS. A simple one word response is 
adequate, but the Executive Committee welcomes 
comments regarding the three options.

John Clague
President, INQUA



John J. Clague
Gordon M. Shrum Professor
Canada Research Chair in Natural Hazard Research
Department of Earth Sciences
Simon Fraser University
Burnaby, British Columbia
V5A 1S6

Bus: (604) 291-4924
Fax: (604) 291-4198
E-mail: jclague at sfu.ca
Web: http://www.sfu.ca/~jclague