Geologic Adjectives, mostly Greek-root words

I think I might be getting really, really picky; but, I'm trying to be consistent.

There is a geologic event called the Taconic Orogeny. This is when the Appalachian Mountains were formed. (They are called the Taconics in Connecticut.) I have just encountered a handful of people calling it the Taconian Orogeny. After doing a Google search, I have a theory that it might be an adjectival form used by people who don't speak American English...or just grammatical slovenliness.

I have no clue what the adjective formation rule would be here. I would like some kind of rule so I can impose grammatical order on some Geotechnical Engineering Reports.

Can anyone help?

PS: In case this helps, this site [link] will explain the Taconic Orogeny. Caveat jargon.

Thanks for your reply, Raul. In a way, this makes it worse. (Imagine me scratching my head in puzzlement.)

How are "relating to" in #1 of the -ic suffix and "relating to" in #1 of the -an suffix different?

From your examples, it seems that -an refers more to people. But, in geology again, we have the Cambrian, Ordovician, and Silurian Periods (although we also have Carboniferous, Triassic and Tertiary Periods) and the Precambrian Era (although we also have the Peleozoic and Mesozoic Eras).

I am planning, now, to change Taconian to Taconic on the basis of frequency of use. Most geologists, geophysicists, and geotechnical engineers use it. I've never heard Taconian before (if all else fails, the imperial approach can be attempted). Google turns up few references to Taconian, but lots and lots to Taconic.

However, I would really like to understand these suffixes. I had to do a whole chapter in chemistry class on the formation of chemical names. We didn't have anything like that in geology and, frankly, the more I think about it, the more I think that geology is sloppy in its naming...or I'm missing something.

Harrumph! I'm from the US and HATE (hate, hate, hate) seeing a new word coined or an old one misused when there is a perfectly good one hanging around, neglected.

I just changed "impacted by" (barf!) to "affected by" in this report and am writing a memo on the use of Taconic in preference to Taconian. Yes, I am managing to get some engineering done, too.

So, what IS the difference between electric and electrical?

I suppose this has been taken care of by now and I don't have a definitive answer but I do have a few comments.  It seems to me geologists, and I am one so I can say this without pointing fingures, frequently use adjectives as nouns.  For instance you referred to the Appalachian Mountains.  Isn't Appalachian an adjective (even though it starts with a capital letter) used as a modifier of mountains to tell where they are - Appalachia.  Another example is the Caledonian Mountians produced by the Caledonian Orogengy that produced mountains ain the region known as Caladonia.  In general this change of form has worked better than the attempt during the late 1960's or possibly early 1980's to change nouns into verbs.  The one example I remember was "rubble" which showed up in a report as "rubbleized" .  That stills sends shivvers through me and I never made better than a C in an English class nor better than a B on the grammer/clarity grade on any geology term paper.  Anyway to the question at had. We don't always use transform the regional geographic into an adjective to as part of the name of either the orogeny or the mountains which resulted.  A couple of examples will illustrate this point.  1) The Wichita orogeny produced a series of small mountian chains including the Amarillo Mountains . This small range is buried so you won't find them on a map but they run diagonally from SE to NW across the Texas Panhandle and stop near the town of Amarillo and thus the name.  They were discovered during the 1920's and 1930's as oil exploration produced subsurface geologic data for the area. 2) The Grand Tetons of northwestern US were not formed during the Tetonic orogeny nor to the best of  my knowledge is there a region known as Teton or Tetonia.  I don't remember during which orogeny these mountains were uplifted.

The short and not so sweet answer to you question as far as I know is that there is no rule.  Perhaps one of the national or internation committees on geologic nominclature have done something on this but even if they have prior names and terminology tend to be preserved in some areas of geology.  If you look in a modern 1st year college geology text book or lab book you will find that formations may have 1 or 2 word names. The first word is a geographic term referring to the location where the formation was first described or to a location where it is particularly well developed and exposed. The second word is either the type of lithology (sandstone, limestone etc) if the formation is predominantly of one type rock or if it is a mixed lithology rock the word formation is used.  For example: Tecovas Formation, named for Tecovas Creek, Potter County Texas and of mixed sand, silt, and clay lithology.  Georgetown Limestone, named for Georgtown Texas (I think) and almost totally limestone. BUT I am writting this from a drilling location in western Oklahoma and we have just drilled through the Hogshooter formation and are now into the Checkerboard.  I'll bet a small amount of money there Hogshooter and Checkerboard are not the names of towns, creeks, or regions anywhere in Oklahoma.

I think you are stuck for finding a rule.  You might try writting to the US Geological Survey or the International Committe on Stratigraphic Nomenclature or some other body that has the authority to make rules about geologic names.

Hope this helps

Darryl Maddox