Saturday, March 29, 2008

Geology terms overdue for retirement?

In the last couple weeks, I've heard a number of comments about geology terms that are unnecessary or outmoded. The Cordilleran tectonicists at the Las Vegas GSA meeting kept making jokes about how they weren't supposed to use "miogeocline" (which means essentially passive margin, and which replaced "miogeosyncline" after plate tectonics became accepted). "Greywacke" also seems to be on its way out. In the geoblogosphere, Olelog asks whether we need the word euxinic. And then there's this wisecrack from Ammon Shea, who is writing a book about reading the Oxford English Dictionary:

For instance trondhjemite is defined as ‘Any leucocratic tonalite, esp. one in which the plagioclase is oligoclase’. I have my doubts as to whether anyone has ever thought to themselves ‘I wonder what trondhjemite means?’ But if someone did, and went to look it up in the OED, it seems unlikely that this definition would clear things up much.

I disagree with Shea. I know what a tonalite is, and I know what oligoclase is, but I often need reminding of the precise definition of "trondhjemite." I've got even more problems remembering the definitions of other igneous rock names ("alaskite," "pantellerite," "hawaiite," "benmoreite," etc.) but that's partly because I've worked in Precambrian rocks, and lots of Precambrian geologists talk about trondhjemites. So I think the definition in the OED is useful, but I'm not so sure that the term itself ought to remain in active use. (By the way, if Shea wants a really impenetrable geologic definition, he should see the definition of cactolith.)

So I'm curious. If you could get rid of five geologic terms as unnecessary and/or outdated jargon, which ones would you choose?

17 comments:

Ole said...

Thank you for the link - which is unfortunately misspelled, and should be:
http://my.opera.com/nielsol/blog/show.dml/1850609

It so happens that Trondhjemite is one of the terms that I like! Maybe because I have seen it at Trondheim, but I am certain we could do without it.

John Van Hoesen said...

Glacial "drift" - oye! I'm astounded that it's still used! It doesn't imply a genesis NOR does it describe a transport or depositional process! DELETE.

:)

1&2 said...

Tertiary.

BrianR said...

flysch

ScienceWoman said...

Do people still really use drift? I don't think I've seen it in anything written in the last 20 years.

And stop banishing geologic time periods. I like the Tertiary and the Quaternary, thank you very much.

I've never been a fan of "basic" and "acidic" for rocks and much prefer mafic and silicic.

Kim said...

Sorry about that, Ole! It's fixed now.

And ScienceWoman, I am with you about acidic/basic. (Also sialic and simatic, while we're at it.) Igneous petrology is particularly bad about duplicate terms.

Brian: if we're going to get rid of flysch, we should also get rid of molasse, shouldn't we?

(And everyone at the Cordilleran section meeting was saying "Tertiary." That one's going to take a long, long time to die off.)

Chuck said...

Richard Arculus has been trying to rid the world of "calc-alkaline".


"The terms calcalkaline and calcalkalic are currently defined and used in multiple and non-equivalent ways."

Abstract here.

Chris said...

I think Precambrian is far to low resolution (you know, the ~4 billion years before the Cambrian, nothing to worry about) and should be done away with. After all, we have the Hadean, Archean, and Proterozoic as useful eras (or even eons).

Silver Fox said...

I've always liked trondhjemite and graywacke. There are tons of gray, dirty, poorly sorted "sandstones" or wackes in Alaska. Andrew has a bit about graywacke here.

Yes, get rid of basic and acidic, also calkalkaline (keeping calc-alkalic).

BrianR said...

yep, get rid of molasse too ... useless terms

Fault Rocks said...

Sounds like some of the terms which might atrophy are the ones with too much "extinct" theory wrapped up in them, e.g. flysch/molase, miogeocline, etc... But I'm keeping graywacke! It's not outdated; there is no reason to replace it with "poorly sorted and chemically immature sand/silt stones".

This might be a regional problem, but diamictites in southern Africa seem to be glibbly called "tillites" without regard to their true origin. This has become a major pet peeve of mine.

zs said...

I agree that, from a sedimentological and basin analysis point of view, there is not much need for 'flysch' and 'molasse'. The problem is that these terms are pretty well entrenched in the European regional geologic literature: it is difficult to talk about alpine or carpathian geology without using 'flysch' and 'molasse'.

effjot said...

zs said:

> it is difficult to talk about alpine or carpathian
> geology without using 'flysch' and 'molasse'.

I didn't know that these terms are used outside alpine geology at all...

(Having grown up in the Alps, I always considered them rather regional expressions.)

andrew said...

I could easily let primärrumpf go by the boards, and nemataph. We probably don't need stoss any more. We should choose either talus or scree and let the other die. But when you need to differentiate an inselberg from a tor or a monadnock, the words must be ready!

andrew said...

And by the way, I used "euxinic" just the other day.

reader of winter's petrology textbook said...

Apparently using mafic/felsic rather than acidic/basic makes you a "true-blue North American".

Dave said...

I'll agree that "glacial" should not be used as a adjective to modify "drift," since "the drift" originates from comets not from glaciers, as was demonstrated by Ignatius Donnelly in: Ragnarok, the Age of Fire and Gravel (1883), but I'm sure that "autochthonous" was dropped from the first edition of the Newspeak dictionary.