Earthworms: Nature's Mineralogists

Everybody knows earthworms are cool; from playing a role in many soil forming processes to serving as excellent fishin' bait, earthworms are some of nature's hardest working critters. Heck, Darwin himself wrote a hefty tome on the subject of the Humble Earthworm, showing in his own imitable style how absolutely amazing and utterly vital to the development of our life-sustaining soils these little fellows are.


Look! A cartoon from Punch about Darwin! What are the odds!?!

One of Darwin's observations in his 1881 volume "The formation of vegetable mould, through the action of worms, with observations on their habits" was that earthworms excreted little calcite balls, up to a millimeter in size, which actually made up an appreciable amount of mass in any given soil volume. Subsequent work has shown that your average worm (Lumbricus terrestris) can produce up to 2.2 mg of Calcite per day, and that this wormogenic calcite is indeed a commonplace feature in soils today.

Recognizing the ubiquity of worm-poop calcite in soils, a recent paper by Lee et al. (2008) in Geology interrogated the shit out of these little limestone pellets (get it!?!). Anyway, apparently no one had really taken the time to do a detailed bit o' mineralogy/petrology on these calcite granules. Lee et al. (2008) used a variety of analysis and imaging techniques, including backscatter electron diffraction, to really get into the nitty-gritty detail of these pellets (ha! another one!).

To get to the point, Lee et al. (2008) found that the calcite was initially precipitated as amorphous calcium carbonate in the guts of the worm (by the appropriately named calcifierous gland). This amorphous calcium carbonate phase gloms onto a quartz grain in the gut of the worm, where it undergoes eventual crystallization into calcite BEFORE being excreted. This crystallization process is mediated by a migrating fluid film, resulting in a stromatolite-esque coated grain (see below for a figure taken from the paper):

Apparently, the fine-scaled zonation of these calcite crystal is unique for biominerals; the authors point out that, given calcite growth rates inside the worm, the properties of the mediating fluid film must have fluctuated on the scale of tens of minutes in order to produce such zoning.

Why go through all that trouble? The authors suggest that crystallization may be a way the worm avoids remobilization and absorption of calcium carbonate. The solubility of the these different phases is dramatically different, and by forcing the amorphous stuff to crystallize into more stable calcite, the worm can ensure the stuff stays put. As for the larger question of "Why do worms secrete this stuff anyway?" is one that the authors can't answer. Apparently, no one knows why worms do this!

Of course, this probably isn't idle musing for cloistered academics. Lee et al. (2008) close their paper by pointing out that the amount of calcite produced by these worms is in such quantities that it probably plays a major role in the soil carbon cycle. As such, a clearer understanding of this process might have an impact on our understanding of and ability to model biogeochemical cycles.

I think Darwin would be pleased that the Noble Earthworm still has some important stories to tell us.

WORKS CITED:

Lee, M.R., Hodson, M.E., and Langworthy, G., 2008, Earthworms produce granules of intricatley zoned calcite: Geology, v. 36, n. 12, p. 943-946.

MAYBE Jindal was RIGHT!?!

David Rees has some very cogent arguments...maybe we need to rethink our policies? Americans can do anything they want...including getting killed by Volcanos! USA! USA! USA!

Nuke Your City!

Nothing like a little apocalyptic terror to make the afternoon go quicker! This google mashup, via CarlosLabs, has a little simulator that lets you pick your city, pick your explosive (anything from a few kilotons up to "asteroid", which I guess is just really really big), and then blast away! You can see the resultant damage zones. Fun And Terrifying!

Bobby Jindal - Nihilist

Bobby Jindal, the potential Dauphin of the Republican Party who seems to be maneuvering himself into potential pres-running position, is an idiot who can't see the value of Volcano Monitoring Programs.

This is of course not news, and has in fact already been well documented in our humble little corner of the interwebs (here, here...and here). Standard issue Republican moronism, I reckon, and just goes to prove my old theory: Republicans Hate Science.

It is complete bullshit on his part, especially what with his being the Gov. of Lousiana and all, and therefore directly dependant on USGS, NOAA, and other Fed Funded Monitoring programs to protect his ridiculous water-logged Basin of a State. However, the best part of this whole thing was David Brooks' analysis of Jindal's response on NPR's Newshour after the fact. Brooks is an idiot Republican too, but this assessment is Rad As Hell:



Bobby Jindal - Nihilist. You Heard It Here!

In the words of Walter Sobchak: "Nihilists! Fuck me. I mean, say what you like about the tenets of National Socialism, Dude, at least it's an ethos."

More Wadi Al-Hitan

Due to Blogger's built-in limitations on picture-size, I couldn't put up all the Wadi Al-Hitan pics I wanted to. As such...BEHOLD! MORE PICTURES OF A RAD PLACE!




The picture above is a little panorama form atop one of the huge mountain-y outcrops in the area; you can really get a sense for how much wandering you can do out there, following out beds and surfaces for as long as you want.




The late afternoon-early evening is really the best time to enjoy the view out there.



And I really can't over-emphasize this...there is a LOT of outcrop to look at in the Wadi Al-Hitan.




And look, HCS! Hot Damn!




Seriously, it's pretty much Geo-Porn.

Geological Holy Lands

Ol' Geotripper is hosting this month's Accretionary Wedge (#16, by the way), the theme of which is "Kickass Geology Spots That You Must Visit" (I paraphrased that, slightly). Anyway, here is my submission:



The Wadi Al-Hitan, in Egypt!

The Wadi Al-Hitan is a UNESCO World Heritage Site, recognized as a place of peculiar Scientific Interest, Cultural Importance, and Scenic Loveliness. I had the opportunity to do a couple weeks of fieldwork down there late last year, and I can attest that the Wadi Al-Hitan is, indeed, completely kickass.

The Wadi Al-Hitan, located in the Western Desert of Egypt, records a phase of Bartonian-Priabonian (Mid-Late Eocene, ~38 - 33 Mya) marginal marine to offshore shelfal deposition. Fine sands, silt, and mud dominate the stratigraphy, and the resultant wind erosion has exposed some spectacular outcrop. The extremely dry climate means that we don't have to contend with that pesky green stuff that grows all over rocks elsewhere; combined with the fact that there hasn't really been any post-depositional tectonism or tilting, and you get a beautiful stratigraphic story laid out for miles and miles at your feet, ready to be walked out, described, and correlated (just bring lots of water, though).

As gorgeous as all that rock is, the wonderful stratigraphy isn't the reason the UN designated the Wadi Al-Hitan a world heritage site. Rather, this is:



That's right. Wadi-Al Hitan (which means "Valley of the Whales" hint hint hint) has a ridiculous amount of vertebrate fossils preserved in it. Among these are thousands of whales, including totally rad specimens of Basilosaurus and Dorudon. The picture above is part of a Dorudon jaw that we found while wandering around the dunes. By the way, those little pits at the end? Those are WHISKER HOLES.



A lot of our current understanding of the evolution of whales actually comes from fossils in this area; on a side note, I would point out that the occurrence of these critters is stratigraphically predictable, which is the point of a soon-to-be-out Palaios paper that I'll talk about soon.

Of course, it's not all about vertebrates, mind you! There are lots of kick-ass inverts, too, including heart urchins...


...and trace fossils!



The Egyptian Government has built a pretty nice little interpretative walk through the area, and there is a place for visitors to camp (and, of course, buy things). Geologically, the Wadi Al-Hitan preserves an incredibly interesting series of lithofacies assemblages, recording the evolution of depositional environments in a fairly unique setting, providing us with an unprecedented view into the evolution of a major group of animals today. I'm pretty sure that's the Webster's Dictionary Definition of "Kick-ass".

So, in conclusion, the Wadi Al-Hitan belongs on everyone's "To See" list, especially if that list is a "Geology Places To See" compilation.

Merry Darwin Day!

Well, here it is; the 200th birthday of good ol' Charles Darwin, easily one of the Great Heroes of Science. Naturalist, Geologist, Biologist, Charles Darwin was, in the words of his contemporaries "totally rad...to the max" (quote attributed to Huxley). It's been a tough 200 years for the man, though. Old Darwin fundamentally changed the way we view historical science, revolutionized the field of biology, and provided key insights in the history of earth and life processes, and yet there are still a bunch of moron's out there that belittle the staggering genius of the man and his work.

Still, between the "staggering inanity" of the Dover Creationists, and the shocking moral and scientific bankruptcy of Stein's "Expelled", I think things are looking up. We just gotta keep up the good fight.



Anyway, in celebration of the man, raise a glass of beer (which depends on the action of Yeast, one of the most important model organisms in evolutionary biology) to Darwin, maybe play some billiards with your butler, and punch a Creationist.

The Bastards!!!

Sonafabitch! While we may have gotten rid of the Buch/Cheney anti-science figureheads, it appears we've still got some insurgency to deal with among the pro-moron contingency in Washington. The bastards are trying to slash NSF funding!

I know things weren't exactly sunshine and puppydogs, but it was nice to see the $3 Billion boost to NSF's funding that was supposed to be coming on. NOW, however, Senators Ben Nelson (D-NE) and Susan Collins (R-ME) are leading an effort to zero out the NSF's funding, as well as whacking considerable chunks off of other science-heavy government projects. Specifically, the cuts are:

NASA exploration $750,000,000 = 50%
NSF $1,402,000,000 = 100%
NOAA $427,000,000 = 34.94%
NIST $218,000,000 = 37.91%
DOE energy efficiency & renewable energy $1,000,000,000 = 38%
DOE office of science $100,000,000 = 100%

We gots ta put things right folks; the Science Debate people have sent out a helpful list of THINGS TO DO, including CALLING and E-MAILING your two state senators. Seriously, guys, do this, ESPECIALLY the "calling" part of the exercise. You can find your senators here.
Important things to mention in regards to protecting science funding include:

A) Science & technology have produced half of the economic growth of the United States since WWII.

B) Spending on basic research is the single greatest economic engine this country has ever known.

C) Funding to federal granting agencies is about as "shovel-ready" a stimulus as you can get. If the granting agencies lower their score thresholds for awards across the board the money will be flowing within months, leading to rapid hiring and increased purchasing from technical service and supply companies that are largely American, and creating thousands of the kinds of high-quality jobs the country needs.

IF THAT DOESN'T WORK, then I guess we'll have to just break out the molotav cocktails and go to work.

Mutants!!!

Darwin Day is fast approaching, and with it, the celebration of all natural science, rationalism, and reasonable thinking everywhere. In honor, let us celebrate with some good ol' fashion mutations!

http://www.ktvu.com/news/18608582/detail.html

The story above talks about a healthy baby boy born in the Bay Area...WITH 12 FULLY FUNCTIONING FINGERS AND TOES (6 digits on each paw). Pretty slick, eh? Hopefully his folks'll let em keep the extra fingers.

Standardizing Sequence Stratigraphy - Are We Still Talking About This?

I'm sure everyone, at some point in their career, develops a bit of a stereotypical view of certain kinds of geologists. You know what I mean; you had a geophysics prof once who was ridiculously quiet and nerdy, or you took a class from a structural geologist who was a white-hot ball of rage. And now, everytime you meet a geophysicist or a structural geologists, you've always got this little niggling suspision that they are they're going to act the exact same way. Part of this might be reinforced by the literature, too; take a look at papers about the Heart Mountain Thrust, and tell me that structural folks don't seem a little...on edge.

I suspect that people might develop a similarly unflattering view of stratigraphers. Specifically, they might decide that we are a bunch of contrarians who can't seem to agree on anything. I mean, we tend to argue about the same things (like eustasy) over and over and over again, with little apparent progress. And frankly, I blame sequence stratigraphy. Ever since AAPG Memoir 26, the sed/strat literature has been rife with arguments, nomenclature, arguments about nomenclature, and discussion on the nomenclature of arguments.

Anyway, just in case anyone was getting worried that things might be quieting down, Octavian Catuneanu and twenty-five others recently published an article titled: "Towards the standardization of sequence stratigraphy" in the journal Earth-Science Reviews! Thank Goodness! Things were getting to quiet around here!

This paper seems to be the summation, in a peer-reviewed venue, of a running gun-battle that Catuneanu et al. have been having with Ashton Embry and others. This terminological war has been documented on the USC Sequence Strat website here, and makes for some entertaining and enlightening (for a variety of reasons, not all scientific) reading, though I suspect beer would help to get you through it all.

Fundamentally, the argument of Catuneanu et al. (2009) is this: sequence stratigraphy has become a very important part of modern sed/strat life. As such, there should be some sort of accepted, formalized rules regarding its deployment and use, thereby allowing us to more effectively communicate our chronostratigraphic work to one another. Importantly, Catuneanu et al. (2009) advocate the formalization of a seq strat framework "sufficiently flexible [to] accommodate the range of likely expressions" of sequence straigraphically important units and bounding surfaces (Catuneanu et al., 2009, p. 1).

A lofty goal, and maybe even an important one. It is true that there exists considerable confusion in the seq. strat literature about what constitutes a "Sequence", and how best to define AND interpret it. However, I have some questions regarding Catuneanu et al.'s approach.

Catuneanu et al. (2009) recognize two facets of the sequence stratigraphic paradigmm, which they identify as "model-independant" verus "model-dependant" aspects. I think the nomenclature here is a little confusing, however. What Catuneanu et al. (2009) mean (I think) by model-independant and -dependant is in regards to INDIVIDUAL uses of sequence stratigraphy. In otherwords, model-independant aspects of the sequence stratigraphic paradigm are those things that everyone agrees on. Model-dependant aspects vary between different practioners. I've reproduced Catuneanu et al's Figure 10 (from Page 8) below, where this dichotomy is illistrated:



Take a gander at that figure, paying particular attention to the "basic concepts" section of the Model-Independant box. I think this is where we are going to get ourselves into trouble; this is the fly in the ointment, the monkey in the wrench, of so many stratigraphic discussions. What is it, you ask?

Baselevel.

Briefly, baselevel is a theoretical, undulating surface that defines relative aggradation or degradation across an earth-surface profile.

OR it is the graded profile of a river.

OR it is sea level.

Brian has an excellent summary of Wheeler's baselevel concept , which you should all go read if you havn't already (the fact I'm linking to it sort of gives away my bias as to what I think baselevel is). Anyway, the baselevel concept is probably one of the most contentious issues in stratigraphy (probably needlessly, but there you go...), and the way it is discussed by Catuneanu et al. (2009) is frankly a little schitzophrenic.

The salient point of the argument about baselevel boils down to the fundamental question of whether baselevel controls sedimentation or erosion by modelating equilibrium surfaces, or whether baselevel is the result of modulations in equilibrium forces dictated by the changing conditions of sediment supply and transport energy. Simplicitically, these can be defined as "geomorphic baselevel" for the former, and "stratigraphic baselevel" for the latter.

Catuneanu et al (2009) start of promisingly enough, citing Wheeler, Barrell, and Cross and Lessinger papers, and discussing the way baselevel plays an important role in the chronostratigraphic paradigm. But in the same sections, they discuss baselevel in terms of sea level fluctuations, and how baselevel for some river systems should be replaced with the graded river concept, effectively conflating geomorphic baselevel with stratigraphic baselevel without neccessusarily distinguishing the two.

The discussion is not purely academic, either. The baselevel concept has a fundamental role in underpinning correlation strategies, and very different ways of looking at strata come from the different ways people use the concept of baselevel. Especially in the nonmarine realm, there are fundamentally important ramifications for interpeting stratigraphy or modeling forcing functions in the rock record that rest soley on how baselevel is used. It's a big deal, folks!

And the fact that Catuneanu et al. (2009) place "baselevel" in the "everybody agrees on it" bin in Figure 10 (above), makes me question whether the time is ripe for a standardized sequence stratigraphy. There still are basic questions about the "How" and "Why" strata are preserved that have yet to be answered, and the answers will have very important implications for the way we do chronostratigraphy. Baselevel stands out, because it is such a contentious issue already, but there are other fundamentals of stratigraphy that still need to be resolved before we start talking about standardization. We have a lot of arguing ahead of us. Which is good! Really it is!

Just be patient with us, is all I ask.

WORKS CITED:

Catuneanu, O., et al., 2009, Towards the standardization of sequence stratigraphy: Earth-Science Reviews, v. 92, p. 1-33.