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

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

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

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