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CNA (Cosmogenic-Nuclide Acronyms)

May 22, 2009

Q: A lot of recent exposure-dating papers use various acronyms in an apparent attempt to reduce the burden of typing “cosmogenic nuclide.” What is the generally accepted acronym?

A: I will begin by reviewing the current state of acronym usage. Here are the acronyms in current use at present:

  • TCN: Terrestrial Cosmogenic Nuclides.
  • CRN: Cosmogenic RadioNuclides.
  • CN: Cosmogenic Nuclides.
  • SED: Surface Exposure Dating.

Here are the relationships between these acronyms:

  • All TCN are CN, but not all CN are TCN.
  • All CRN are CN, but not all CN are CRN.
  • Some TCN are CRN.
  • Some CRN are TCN.
  • Some, but not all, CN are TCN. Others, but not the same ones, are CRN.
  • Only some TCN, CN, and CRN can be used for SED.

Some people may find this confusing. To clear things up, here is a Venn diagram:

Venn diagram

Venn diagram

Is everything clear now?

Seriously, discerning readers will by now have noticed that I am making fun of this ridiculous alphabet soup. I don’t ever use any of these acronyms in publications, and I don’t think anyone else should, for the following reasons.

First of all, the basic purpose of using an acronym is to replace a word or phrase that is so cumbersome that it breaks up a sentence — by the time you get to the end of the phrase, you have forgotten what the sentence is about. For example, consider the instrument called a “Super High Resolution Ion Microprobe.” If you wrote “Super high resolution ion microprobe analyses revealed uranium,” you’d have wasted 63% of the sentence describing the instrument, so sensible people might well call it a SHRIMP by the time they got to the second or third such sentence.

A good acronym, even an acceptable one, must have two characteristics: it must save a significant amount of text, and it must be exactly as specific as the word it replaces, that is, it must not lose any information or introduce any confusion.  Geoscientific acronyms besides SHRIMP that pass these tests include LIS for Laurentide Ice Sheet; OSL for Optically Stimulated Luminescence; or PRZ for Partial Retention Zone. These acronyms drastically reduce the number of characters required and communicate exactly the same information as the full phrase.

The cosmogenic-nuclide-related acronyms summarized above nearly always fail both of these tests. They fail the space-saving test because the vast majority of cosmogenic-nuclide exposure-dating papers only involve one nuclide, usually Be-10. Replacing “Be-10″ with ‘TCN” doesn’t do much, except possibly to benefit true couch potatoes who can’t be bothered to mouse over to the “superscript” button in MS Word.

They fail the specificity test for the same reason: most authors haven’t measured multiple cosmogenic nuclides, or some sort of theoretical generic cosmogenic nuclide — they’ve measured Be-10. Using a generic acronym, that could refer to any of a large array of different nuclides, actively loses information (the nuclide that was actually measured) and adds confusion. There is no such thing as a “TCN exposure age:” there are only Be-10 exposure ages, Cl-36 exposure ages, etc. Imagine a paper that represented all isotope-geochemical age determinations by a single acronym (IGAD): readers would have to go deep into the supplemental online material to determine whether they were reading about a radiocarbon date or a Rb-Sr isochron, and would have very little hope of gaining any information from the paper. In papers that involve two or more cosmogenic nuclides, the confusion can be very bad: the concentrations of different nuclides give different information, and if the reader can’t keep track of which is which, there is little chance of figuring out what the author is trying to say.

These objections are true in the vast majority of cases. Using”CN,” “CRN,” or “TCN” to refer to measurements of a specific cosmogenic nuclide actively destroys information and generates unnecessary confusion without significantly shortening the text. The one exception in which it might be appropriate to use one of these acronyms is when one is making general introductory remarks about cosmogenic-nuclide exposure dating or erosion rate measurements that apply to many different nuclides. For example, one might say that “Cosmogenic nuclides (CN) have become very fashionable in geomorphology. CN concentrations reflect the length of time that surface rocks have been exposed to the cosmic-ray flux, so they allow bright people to quantify how fast surface features evolve.”

To summarize, in nearly all cases the acronyms “CN,” “CRN,” “TCN,” and “SED” fail both tests for a good acronym. Don’t use them. If you’re tempted, sit down and read George Orwell’s essay Politics and the English Language (the section on “jargon”) before continuing.

3 Comments leave one →
  1. Mike kaplan permalink
    August 25, 2009 15:05

    I agree – I have always disliked the use of these acronyms also and say so in reviews. In addition, most people use them at most just a few times in a manuscript anyway

  2. Lewis permalink
    July 4, 2011 23:02

    Bloody hell. Someone has too much share time.


  1. Snow shielding by muons? « The bleeding edge of cosmogenic-nuclide geochemistry.

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