Skepticism

Geology Word of the Week: Burdigalian


Foraminifera, little sea critters whose fossilized skeletons are often used to define geologic ages.

Q: What do the words Burdigalian, Zanclean, and Maastrichtian have in common?
A: They’re all Ages of geologic time! So are the Tithonian, Albian, Sinemurian, Norian, and dozens of others.

Never heard of the Burdigalian? Don’t worry, I had never heard of it either before I did a little research for this skepchick post. I have only memorized the geologic timescale through the Epochs, and then only for the Cenozoic (65 million years ago to present).

The Burdigalian is defined as the geologic Age which spans from 20.43 ± 0.05 million years ago to 15.97 ± 0.05 million years ago. You might be thinking to yourself that this is a strange bracket for geologic time. Why not just make it an even 20-15 million years ago? If you look closely at the geologic timescale you’ll notice that the geologic Ages (as well as the Eons, Eras, Periods, and Epochs… but we’ll get to that in a minute) are all different lengths of time that seem random.

The geologic Ages do span inconsistent lengths of absolute time. This is because Ages such as the Burdigalian (which was first used in the geologic literature in 1892) were defined long before absolute dating of rocks became possible after the discovery of radioactivity in the late 1800s and the development of radioactive dating of rocks and minerals in the early to mid 1900s. We’ve only been able to confidently determine absolute ages for rocks since the 1960s or so, and every year our techniques for dating rocks become better with smaller error bars.

Remarkably, geologists defined the entire geologic timescale (although standardizing this timescale internationally is still an ongoing process) prior to the development of absolute dating of rocks and minerals. Although the absolute ages were unknown, geologists were able to work out the time periods based on the evolution of the fossil record. The main divisions of time are based on time periods when certain types of ancient organisms lived.

Boundaries between different periods of geologic time often mark periods of mass extinctions where there was a sudden, dramatic change in the fossil record. The most famous example of this is the boundary between the Tertiary and the Cretaceous, also known as the K-T boundary. This boundary ~65 million years ago is marked by a mass extinction event famously known to have wiped out all non-avian dinosaurs. The boundary is known at the K-T boundary because “K” is used for Cretaceous and “T” is used for Tertiary on geologic maps and other places where shorthand is appropriate. Geologists have known for generations about boundaries such as K-T and about ages such as the difficult-to-say Burdigalian, but it has only been in the second half of the 1900s that they were able to start assigning absolute ages to these geologic times.

I mentioned above that I had never really heard of the Burdigalian before. That’s true– I have never bothered to memorize the geologic Ages, one of the smallest divisions of geologic time, and the smallest one recognized by the International Commission on Stratigraphy or ICS. I don’t think I will ever bother to memorize them as I can easily look them up and, honestly, I think it’s a bit silly to subdivide geologic time into such small sections. Whenever I read papers that bother with naming various Ages, I just keep a copy of the geologic timescale nearby. I have taken the time to memorize the larger divisions of geologic time, which are (from largest to smallest): Eons, Eras, Periods, and Epochs. And, as I mentioned previously, I’ve only memorized the Cenozoic Epochs because they’re the only Epochs with names. Otherwise, it’s just “early,” “middle,” and “late,” and I find these very difficult to memorize.

The way that I originally memorized the Periods and so on was through use of mnemonics. My favorite mnemonic for the geologic Periods is Cold Oysters Seldom Develop Many Precious Pearls, Their Juices Congeal Too Quickly which helps me remember: Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary.

For the Cenozoic Epochs, I like the mnemonic Pigeon Egg Omelets Make People Puke Hourly which helps me remember Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene.

So perhaps what I need to remember the Ages is an appropriate (and very long!) mnemonic. I propose a challenge to the skepchick readers: come up with a mnemonic for the geologic Ages. The Ages are: CALABRIAN, GELASIAN, PIACENZIAN, ZANCLEAN, MESSINIAN, TORTONIAN, SERRAVALLIAN, LANGHIAN, BURDIGALIAN, AQUITANIAN, CHATTIAN, RUPELIAN, PRIABONIAN, BARTONIAN, LUTETIAN, YPRESIAN, THANETIAN, SELANDIAN, DANIAN, MAASTRICHTIAN, CAMPANIAN, SANTONIAN, CONIACIAN, TURONIAN, CENOMANIAN, ALBIAN, APTIAN, BARREMIAN, HAUTERIVIAN, VALANGINIAN, BERRIASIAN, TITHONIAN, KIMMERIDGIAN, OXFORDIAN, CALLOVIAN, BATHONIAN, BAJOCIAN, AALENIAN, TOARCIAN, PLIENSBACHIAN, SINEMURIAN, HETTANGIAN, RHAETIAN, NORIAN, CARNIAN, LADINIAN, ANISIAN, OLENEKIAN, INDUAN, CHANGHSINGIAN, WUCHIAPINGIAN, CAPITANIAN, WORDIAN, ROADIAN, KUNGURIAN, ARTINSKIAN, SAKMARIAN, ASSELIAN, GZELIAN, KASIMOVIAN, MOSCOVIAN, BASHKIRIAN, SERPUKHOVIAN, VISEAN, TOURNAISIAN, FAMENNIAN, FRASNIAN, GIVETIAN, EIFELIAN, EMSIAN, PRAGHIAN, LOCKHOVIAN, PRIDOLIAN, LUDFORDIAN, GORSTIAN, HOMERIAN, SHEINWOODIAN, TELYCHIAN, AERONIAN, RHUDDANIAN, HIRNANTIAN, KATIAN, SANDBIAN, DARRIWILIAN, DAPINGIAN, FLOIAN, TREMADOCIAN, STAGE 10, STAGE 9, PAIBIAN, GUZHANGIAN, DRUMIAN, STAGE 5, STAGE 4, STAGE 3, STAGE 2, FORTUNIAN.

Phew! I hope I didn’t miss any of the ages. I apologize that they are all written in capital letters. I’m not yelling at you. I just copied and pasted the names from a geologic timescale, and I’m too lazy to change them out of all capital letters.

So, see if you can come up with a long-winded mneumonic. You know, something like:

Campbell gave pretty, zany, messy, terribly sexy, lovable, bright, amazing, cheerful Rachel praises by letters youthfully, tentatively sent. Did Mister Campbell say convincing truths carefully ascertained about beautiful, hauntingly vividly beautiful, tantalizing, kiss-invoking, outstanding, creative, breathtaking, blushing, all-knowing, terrific, pleasing, scintillating, hot Rachel? No. Courage leaves an overwhelmed, inconsolable Campbell. Why?! Campbell wondered. Rachel knows a summer affair grows kinda muted because summer visions tear, famously fragmenting ephemeral, end-bound, primitive love. Perhaps lust graces hot summer times, announces Rachel. However, keep summer dreams dampered, flowing temporally, staying 10, staying 9, painfully gone days, staying 5, staying 4, staying 3, staying 2, forgotten.

Please improve upon my rather “film noir”, adjective-filled, and, admittedly, very terrible mneumonic. Though, on second thought, I don’t think this (or any) epic mnemonic is going to be that helpful in memorizing geologic Ages. On third thought, memorizing the geologic Ages is stupid. The only reason I can fathom for memorizing the Ages is to impress geology friends at a bar. Maybe I’ll work on it sometime, but honestly I think it’s only marginally more useful than memorizing digits of pi.

Evelyn

Evelyn is a geologist, writer, traveler, and skeptic residing in Cape Town, South Africa with frequent trips back to the US for work. She has two adorable cats; enjoys hiking, rock climbing, and kayaking; and has a very large rock collection. You can follow her on twitter @GeoEvelyn. She also writes a geology blog called Georneys.

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11 Comments

  1. They really should teach basic programming in high school. In Python:

    print ‘ ‘.join([x.title() for x in ‘CALABRIAN, GELASIAN, PIACENZIAN, ZANCLEAN, MESSINIAN, TORTONIAN, SERRAVALLIAN, LANGHIAN, BURDIGALIAN, AQUITANIAN, CHATTIAN, RUPELIAN, PRIABONIAN, BARTONIAN, LUTETIAN, YPRESIAN, THANETIAN, SELANDIAN, DANIAN, MAASTRICHTIAN, CAMPANIAN, SANTONIAN, CONIACIAN, TURONIAN, CENOMANIAN, ALBIAN, APTIAN, BARREMIAN, HAUTERIVIAN, VALANGINIAN, BERRIASIAN, TITHONIAN, KIMMERIDGIAN, OXFORDIAN, CALLOVIAN, BATHONIAN, BAJOCIAN, AALENIAN, TOARCIAN, PLIENSBACHIAN, SINEMURIAN, HETTANGIAN, RHAETIAN, NORIAN, CARNIAN, LADINIAN, ANISIAN, OLENEKIAN, INDUAN, CHANGHSINGIAN, WUCHIAPINGIAN, CAPITANIAN, WORDIAN, ROADIAN, KUNGURIAN, ARTINSKIAN, SAKMARIAN, ASSELIAN, GZELIAN, KASIMOVIAN, MOSCOVIAN, BASHKIRIAN, SERPUKHOVIAN, VISEAN, TOURNAISIAN, FAMENNIAN, FRASNIAN, GIVETIAN, EIFELIAN, EMSIAN, PRAGHIAN, LOCKHOVIAN, PRIDOLIAN, LUDFORDIAN, GORSTIAN, HOMERIAN, SHEINWOODIAN, TELYCHIAN, AERONIAN, RHUDDANIAN, HIRNANTIAN, KATIAN, SANDBIAN, DARRIWILIAN, DAPINGIAN, FLOIAN, TREMADOCIAN, STAGE 10, STAGE 9, PAIBIAN, GUZHANGIAN, DRUMIAN, STAGE 5, STAGE 4, STAGE 3, STAGE 2, FORTUNIAN.’.split(‘ ‘)])

  2. Had to comment on this one, cos I’m a geology geek too…

    I have a big geologic timescale book sat on my desk, so never intend to learn the geologic ages. But my favourite mnemonic for the periods is:

    Purple Camels Often Sit Down Carefully. Perhaps Their Joints Click.

    For some reason we don’t tend to use Mississippian and Pennsylvanian much in the UK (we lump it all together as the Carboniferous).

  3. Love these features! I live in such a bubble of medical, biological and chemical sciences that it’s a treat to learn about something new. In medicine we use a ton of mnemonics and most are “dirty” in some way- yours seem pretty tame.

  4. When I studied Geology in Britain, the mnemonic we were taught was “Cows Often Sit Down Carefully; Perhaps Their Joints Creak. Early Oiling May Prevent Premature RHeumatism”, which divides the Tertiary and Quaternary into epochs.

    The “Rh” in the last word allows for either “Recent” or “Holocene” depending on which textbook you’re reading.

  5. Whew, I tried to come up with a mnemonic device for those geologic ages, but after a half hour I had to admit defeat. I love this GWotW feature though. Please keep the geology posts coming!

  6. Evolutionary biology word-of-the-week: “Pancrustacea”. A grouping of species including all of the crustaceans and hexapods (which include insects), which is hypothesized to be monophyletic (i.e. there was a single ancestor whose set of descendants is equal to the group Pancrustacea.) Be careful about ordering a pancrustacea pizza: that meat might be lobster, but then again it might be from a large stick insect.

    A (scientifically well respected) former boss of mine held that the mammals and birds were displacing the (non-avian) dinosaurs and pterosaurs well before the KT boundary, and the dinosaur extinction and KT impact were pretty much coincidental – at best the asteroid impact brought the extinction of the dinosaurs forwards a few million years.

    A favourite mnemonic: “Only bored astronomers find gratification knowing mnemonics” (for the spectral classes of stars: O, B, A, F, G, K, M from hottest to coolest.)

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