Period Map Symbols (was RE: Alternatives to K-T boundary?)

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

David pointed out that I forgot to send this to the list as a whole.
Sorry!!

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> David Marjanovic
>
> > If the term "Tertiary" is acceptable only in the United States,
> > what does everyone else call the "K-T boundary"?
>
> K-Pg boundary. The abbreviation Pg is AFAIK not official,
> though*, and it'll
> take some time for the T to disappear from everyone's heads! :-)

Correct, especially as the US Geological Survey still uses it...

> * So far, the symbols for periods don't consist of more than one
> character.
> "Tr" for Triassic actually consists of a T with a small capital R fused to
> it.

Correct, all the Period symbols are single characters.  I do not know if the
French code has formal symbols for Paleogene and Neogene.  For the rest,
here is a verbal list:
Quaternary      Q
Tertiary        T
Cretaceous      K
Jurassic        J
Triassic        Tr (T with a small capital "R" attached)
Permian P
Carboniferous   C (THIS is the reason that Cretaceous has a "K")
or      Pennsyvlanian   |P (capital "P" with a vertical line immediately to the
left)
        Mississippian   M
Devonian        D
Silurian        S
Ordovician      O or a capital Theta
Cambrian        C- (capital "C" with a small horizontal line cutting across the
midpoint. Optical scanners often incorrectly read this as an "E")

I do not know if they have decided on formal symbols for the Ediacaran,
Cryogenian, etc. yet.

Incidentally, these are TECHNICALLY System symbols, not Period symbols. They
are used to mark the location of bodies of rocks on map. As such, they
represent the rock units (Systems) rather than the time units (Periods).

Hope this helps,

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796