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Re: Resurrection of the Quaternary (was RE: Precisely Dating The KT Boundary)
(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
(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
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:
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
225 South 700 East
St. George, UT 84770 USA
Phone: (435) 652-7758
Fax: (435) 656-4022
"Actually, it's a bacteria-run planet, but
mammals are better at public relations."
-- Dave Unwin