Re: Resurrection of the Quaternary (was RE: Precisely Dating The KT Boundary)

["Jerry D. Harris" <jharris@dixie.edu>]

Tom wrote:

> >  (So is Quaternary.)
>
> False. Or rather, it's gone but has been recommended for return in a 
> rather (in my opinion) ugly form. Here is the short form of the
> recommendation by the "Quaternary Task Group jointly of the International 
> Commission on Stratigraphy (ICS, of the International
> Union of Geological Sciences, IUGS) and of theInternational Union for 
> Quaternary Research (INQUA)":
>
> 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.]
>
> Here's the complete recommendation at the ICS website
> http://www.stratigraphy.org/Q2.pdf
>
> Bad, BAD Cenozoic stratigraphers! We let you get away with too much for 
> too long! And now you want a period (or Sub-Era) whose
> boundaries are NOT CONGRUENT with Stage boundaries!?!?

   News to me, and I agree...I don't see much point in having any period 
defined by something other than stage boundaries!  I'm guessing that they 
want this for one of two reasons: (1) it is a nice unit of time in which 
much of immediate human & hominid history has occurred, and (2) it probably 
brackets the time period for which extremely fine-scale geologic data 
(climate data, etc.) can be readily obtained.  Dunno any of that for 
certain, though.

> K/Pg.  P = Permian. Pg is the new symbol for the Paleogene.

    The first time I saw "K/P boundary," I said the exact same thing, and I 
agree that this is what it _should_ be called, and am more than happy to do 
so myself.  However, most of the papers I've seen already that discuss the 
boundary and eschew the term "Tertiary" have, for whatever (albeit 
erroneous) reasons, called it the K/P or K-P boundary.  My guess is that it 
still rolls of the tongue nice and smooth, just like K/T boundary did. Even 
the 2004 Geologic Time Scale:

Gradstein, F. M., J. G. Ogg, and A. Smith. 2004. A Geologic Time Scale 2004. 
Cambridge University Press, Cambridge, 589 pp.

...get this wrong, and call it the K-P boundary (e.g., p. 387). 
Interestingly, I haven't spotted anywhere in the book where they use "P" as 
an abbreviation for Permian (or, for that matter, where they discuss 
appropriate abbreviations at all, which I would assume that they also govern 
along with the nomenclature) -- instead, they always spell out the names of 
the boundaries (e.g., "Carboniferous-Permian," p. 253 or "boundary between 
the Carboniferous and Permian," p. 251; also, they don't seem to ever refer 
to a "Permian-Triassic" boundary, but use "Paleozoic-Mesozoic boundary" 
instead, which is fine).  A peculiar omission, to be sure, and it leaves 
things up in the air: either the abbreviations have changed so that "P" now 
means "Paleogene," or they made a rather egregious error and countradicted 
their own rules, but either way, left things unexplained!  Sure, K/Pg 
boundary doesn't sounds as nice verbally as "K/P" or "K/T," but I agree it's 
better.  Still, it's not what people seem to be using, e.g.:

Schulte, P., R. Speijer, H. Mai, and A. Kontny. 2006. The 
Cretaceous-Paleogene (K-P) boundary at Brazos, Texas: sequence stratigraphy, 
depositional events and the Chicxulub impact. Sedimentary Geology 184: 
77-109.

Arenillas, I., Arz, J.A., Molina, E., and Dupuis, C. 2000. The 
Cretaceous/Paleogene (K/P) boundary at Ain Settara, Tunisia: sudden 
catastrophic mass extinction in planktic foraminifera.  Journal of 
Foraminiferal Research 30: 202-218.

though I have no idea why.  Maybe it's 'cuz Cretaceous workers always forget 
there was a Permian long before there was a Paleogene??? 
Chronostratigraphic tunnel vision?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
and     dinogami@gmail.com
http://cactus.dixie.edu/jharris/

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