Tuesday, September 30, 2008

New Sed Blog!

Enough of that politcs stuff! Behold, fellow blog-o-nauts! A NEW SED/STRAT/PALEO BLOG THAT I HAVE RECENTLY BECOME AWARE OF:

Sed-Line News

With every new blog, we come closer to the eventual Scientocracy!

ALSO, it is powered by Wordpress, so Brian over at Clastic Detritus should be happy.

Fire walk with me

"Fellas, coincidence and fate figure largely in our lives" - FBI Special Agent Dale Cooper

Delving deeply into the various forbidden branches of human and inhuman knowledge (as we graduate students are, by necessity and temperament, often wont to do) can have unforeseen consequences, the least of which not being that the maddening truth may often be brought forth into the harsh light of our awareness. In such cases, only the nepenthe of true insanity can save us.

Behold, if you dare, the horribly revealed truth of such dark illuminations as I have known:

Sarah Palin looks ALMOST EXACTLY like Laura Palmer! It's uncanny! The same vacuous stare, the pained grin, the tower of hair. And if you think about it, the potential VP has a lot more in common with the horribly murdered small-town girl from Twin Peaks. Both were beauty queens, both had a crippling coke habit, both are subject to cosmically evil forces beyond the ken of Man.

I think I may be on to something.

Watch the Owls; they are not what they seem...

Monday, September 29, 2008

Banned Book Week

This week, Sept 27 - Oct 4, is the American Library Associations' Banned Books Week, where all freedom-loving patriots in this country should reaffirm their staunch support of intellectual and literary freedom. Banned Book Week has been celebrated since 1982, and serves to fundamentally remind us that, though every book may not be for everyone, we have the personal choice to right to access any written material we may want. You can access a list of the most frequently challenged books right here.

Note something about that list. The old standbys are there, of course: Slaughterhouse Five (for portraying war and murder in an unpatriotic light), Huckleberry Finn (for racism, which just goes to show you don't have to understand and idea to hate it), and everything Toni Morrison ever wrote, including grocery lists and post-it notes. Having these books on the list is no surprise, but what may come as a shock is the large number of Kids Books on the list, particularly those that seek to advance a view point of tolerance and acceptance of those different from ourselves. I wonder if it is the topic these folks find offensive, or is it the acceptance that is so verboten?

As scientists, science-enthusiasts, or just your basic good-hearted sorts, we can all appreciate the importance of fostering a diverse assemblage of worldviews in a publicly accepting and understanding intellectual environment. As such, we can all appreciate the importance of observing banned book week in principle. However, this year's Banned Book Week coincides rather nicely with something of equal, and not unrelated, importance.

That's right; on Thurs, 2 Oct, the VP debate is slated to begin. And Sarah Palin, the barely literate, fundie-wackjob of the season is going to get a public forum to spew her particularly noxious brand of conservatism. As part of her proud, neo-con CV, Palin tried to fire librarians and get some books banned in her home state of Alaska.

You know who else likes to ban books, Sarah Palin? Terrorists. And Nazis. And Fascists of all stripes. So, as a generalization, I think we can all agree that people who like to ban books are Assholes.

Sarah Palin is an Asshole.

So I encourage everyone to support the Banned Books Week in any way they can, most importantly by taking some time out to read a banned book. Because every time you read a banned book and exercise your rights as a citizen, Sarah Palin cries.

AND, if you need more proof (presented in a hilarious format) that Sarah Palin is batshit crazy evil, take a gander at the clip below (warning: there is some blue language):

Tuesday, September 23, 2008

Isotopes and Paleodrainage

Isotope geochemistry is one of those sexy topics that has captured a lot of attention in the past decade (or more), and some of that attention is even deserved (oh! Burn on Isotopes!). Isotopic records have proven to preserve interesting, if sometimes occult and difficult to interpret, patterns of change from many different depositional environments and basins. Often times, these records are used in the dark arts of paleoclimatology, where it is hoped that temperature driven isotopic fractionation can be parsed out from authogenic minerals.

However, there are alternative mechanisms for getting different isotope values into a basin. Very recent work (it came out today) by Carroll et al. (2008) attempts to link isotopic changes preserved within some of the Green River lacustrine strata with evolution of the drainage system in the hinterland. Basically, these authors attribute changes in O and Sr isotopes to drainage capture of high elevation sources in the Cordilleran foreland system.

Lake Gosuite was a Big Ass Lake (BAL in the technical parlance) in the Eocene of southwestern Wyoming; the resultant stratigraphy of these deposits is actually incredibly complicated and cool, though Carroll et al. (2008) focus on the specific interval that saw the deposition of the LaClede "Bed", which are actually a group of related, carbonate rich bedsets that record alternate phases of lake expansion and contraction.

Anyway, previous work in the basin has identified a distinct stratigraphic surface, the "fill to spill surface", across which a considerable change in isotope values in preserved. The figure below is from the Carroll et al. (2008) paper, and is their Figure 2 (on page 792).

What the figure shows is a rapid decrease of delta 18 O values for this interval, dropping from ~+26 parts per mil to ~+20 parts per mil in the Upper LaClede Bed. A concomitant decrease of Sr isotopes, from 0.712296 +/- 0.0004000 to 0.711638 +/- 0.000274 is also recorded (page 792 of Carroll et al. 2008). What could have caused such a dramatic change (the authors are glad you asked)?

Diagenesis is ruled out, on the basis of a lack of textural evidence for alteration in the mudstones. Furthermore, widely dispersed outcrops record the same shifts in O and Sr isotopes. Additionally, diagenesis would be expected to have produced lower delta 18 O values than reported by Carroll et al. 2008. The authors conclude that this is not a diagenetic signature; so what is it?

One explanation is a direct change in climate in the basin, such as wetter conditions in Lake Gosiute. However, based on Carroll et al. (2008)'s mass balance model, a shift of the magnitude reported above would require a 4x increase in precip OR a 50% decrease in evap (or some combination). The problem with this idea, however, is that there is no sedimentological OR paleontological/paleobotanical evidence for such a dramatic climatic change at this time.

The authors conclude that a more probable explanation is river capture of a more northernly drainage, with differently sourced waters bringing in different isotopic values into the basin. This is supported by the fact that, simultaneous with the change in isotope values, is an increase in volcaniclastics (probably sourced from the Idaho and southwestern Montana volcanic fields) within the basin. By simply capturing a river that might be sourcing a higher elevation, the resultant system could dramatically change its isotope value without having to undergo some sort of huge climate shift.

It is an interesting read, and suggests that the record of climate, as derived from isotopes, may be complicated by more processes than previously recognized. Similarly, it makes me wonder about paleoaltimetry estimates; could those records be affected by the size and source of the drainage in the adjacent sed/water delivery system?


Carroll, A.R., Doebbert, A.C., Booth, A.L., Chamberlain, C.P., Rhoades-Carson, M.K., Smith, M.E., Johnson, C.M., and Beard, B.L., 2008, Capture of high-altitude precipitation by a low-altitude Eocene Lake, western U.S.: Geology, v. 36, p. 791-794.

Friday, September 12, 2008

The Cave of Lascaux

Today, September 12, is the 68th anniversary of the discovery of the famous cave paintings at Lascaux, France. These 16,000 year old cave paintings are really pretty spiffy, and include over 2000 individual paintings of figures, including Bulls...


...and a strange bird-headed man being charged by a Bull. Note the Rhino in the lower left of the picture below (scientific fact: Rhinos are cool).

The Cave was discovered by four boys out for a jaunt in 1940. It has since become one of the most important Paleolithic sites in the world, and was declared a UNESCO World Heritage site in 1979. There is a pretty slick Lascaux Website run by the French Ministry of Culture that has lots of pretty pictures of the cave art, and more info about the research that has gone on there.

Everybody should go out and kill a mammoth in honor of their ancestors today; barring that, I guess drinking a beer in their honor would be alright, too.

Wednesday, September 10, 2008

Burrowing Mechanics

It's International Trace Fossil Day (not really), so let's talk about bioturbation!

One of the perennial problems with animals burrowing into sediment has been the presumption that, energetically, it is way more costly than walking, running, swimming, or flying, especially when you are burrowing into cohesive sediment. As such, it has always been a little tricky to understand why any critter would be willing to expend so much energy in evolving into a benthic bioturbator. Additionally, part of the problem seems to have been that physically studying the energy use of a burrowing critter in situ is a bit tricky. As such, folks in the past used Newton's Third Law as an assumption, and always seemed to come up with burrowing as a very high cost (metabolically) biological activity.

However, some fairly recent studies by Dorgan et al. (2005) and Dorgan et al. (2007) have overturned some of these assumptions through novel and (to me, at least) insightful experimental design. To give away the punch line, burrowing is actually much easier than we had previously thought, since animals can use crack propagation to move through muddy sediments, expending much less energy than the previous models of whole-animal burrowing indicated.

First off, both of these papers point out that previous studies of animal burrowing always took place with the animal near a rigid wall (like the transparent edge of an aquarium); as such, the animal behavior exhibited was not, energetically, the same as moving through deformable sediment. In order to overcome this wall effect, the workers used a transparent gelatin as their muddy sediment analog, which has similar mechanical properties to marine muds. Also, and this is the slick part, gelatin is birefringent, meaning that the workers could look at it through polarized light and clearly track the deformation occurring around the critter AS IT HAPPENED. Nifty, huh? The picture below (and the caption) was seized from the Dorgan et al. (2005) paper.

The worm (Nereis virens) moved through the gelatin by exerting a dorsoventral force against the walls of its burrow, resulting in an oblate hemispherical crack; stresses are concentrated at the tip of this crack, and exceed the critical stress needed for the crack to propagate. In otherwords, the worm creates a wedge-driven fracture (like an axe being struck into a log), rather than actively excavating a vacuity in the sediment. The picture below, also from the Dorgan et al. (2005) paper, explains the whole process visually.

The results of this study match (or exceed) modeled critical intensity stress values for sediment, suggesting that crack propagation processes are a viable burrowing mechanism. It's a pretty slick study, I think, and shows how some of the benthos may do their burrowin' in the sediment.


Dorgan, K.M., Jumars, P.A., Johnson, B., Baudreau, B.P., and Landis, E., 2005, Burrow extension by crack propagation: Nature, v. 433, p. 475.

Dorgan, K.M., Arwade, S.R., and Jumars, P.A., 2007, Burrowing in marine muds by crack propagation: kinematics and forces: The Journal of Experimental Biology, v. 210, p. 4198 - 4212.

Friday, September 5, 2008

Church of the Archosaur (Reformed)

Courtesy of the sleepy burg of Dinosaur, CO:

Finally! A Church I can believe in!

Monday, September 1, 2008

Greater Green River Intergalactic Spaceport

Howdy folks; well, the field season ends, and the semester begins, thus continuing the eternal cycle of academia, red in tooth and claw. It's always tough to leave the solitude of the field, but, such is life. It's especially tough to leave Wyoming, a state known for having a pretty rich crazy-to-citizen ratio.

The town of Green River has its very own "airport", just like it's rowdy, ne'er-do-well bigger brother to the east, Rock Springs. But, where the Rock Springs Airport is all glitzy and "show-business" (having obviously left its small-town, simple-livin' ways behind it), the Green River keeps true to the honest, western simplicity that made this country great. Eschewing new fangled concepts like "asphalt", "radio", or "buildings", the Green River airport is a simple dirt track, located a few miles south of the (mormon-)God-fearin' town of Green River proper.

Also, the airport is officially named "The Greater Green River Intergalactic Spaceport," in honor of the wind-driven madness that has affected Wyoming lo these many years. You can check out the official listing for the airport right here.

Of course, having been out in the wilds of Wyoming for months, I too was driven mad by the stark beauty of the windy high desert, so I deliberately went out to find the Spaceport, and provide some pictures for you.

The picture above is the only man-made structure at the spaceport, a windsock and windsock pole.

This picture looks North, up the gravel runway.

This picture looks South, down the gravel runway.

I felt closer to the cosmos just standin' there; we must all do out part for intergalactic peace and goodwill, even with the dastardly Reptoids of Alpha Draconis.