Another comic!

Man, I promise, i'm just really busy. It's not like I ONLY sit around lookin' at internet comics all day or anything...just got a lot on my plate, alright? DON'T JUDGE ME!



Anyway, the comic below is from Big Fat Whale, purveyor of transgressive snark since 1324, with a royal charter from King Edward II himself! Enjoy!

Climate Change Deniers are Idiots

The title pretty much sums up my definitive policy statement on climate change deniers. Emily Flake, of the completely rad LuLu Eightball comic strip, explores the intricacies of various "reasons" for actively denying reality. I snagged it, from the interwebs, and reproduce it for you below. ENJOY!

Pretty accurate, really.

The Return of Sunday Sed Structures!

A substantial hiatus between "Sunday Sed Structures", perhaps, but seeing as how I'm a fan of the ol' Sed/Strat side of things, I reckon it's perfectly acceptably for me to engage in hiatuses of all sorts (as well as terrible pun-based stratigraphy humor). Below is a picture from the Holiest of Holies, The Book Cliffs!

A pretty big piece of float, perhaps, but it illustrates the elusive and complex 3-Dimensional nature of bedforms rather nicely, I think. On the right-hand face of the boulder, you can see the more traditional trough cross-stratification, oriented roughly parallel to flow. On the left-hand face, you can see the troughs themselves; this view is roughly perpendicular to flow, and preserves the scoop-like trough that is the cross-stratification's namesake. Just goes to show you that when dealing with trough cross-stratification and paleocurrent orientation, you gotta be careful, and TRY to find some nice 3-D (or, more likely, the good ol' 2-and-a-half-D) exposure.

Geophysics and Auto-Tuning

Despite the common perception that Auto-Tune is an insidious font of evil, born in blackest night by the dreaded Audiomages of Sauron the Great, it can OCCASIONALLY be used to produce some pretty nifty stuff, I GUESS. I'm sure everyone has already encountered the "Symphony of Science" and it's (pretty fun, actually) Auto-tuned Carl Sagan (and others) videos.

But do you know whence Auto-Tune actually sprang? Andy Hildebrand is the name of the inventor, and he worked for Exxon as an engineer, specializing in seimsic data processing. He's also one of the founders of Landmark Graphics, which is all geophysicsy too. Apparently, Dr. Hildebrand recognized that his digital signal processing mojo could also be employed to detect, analyze, and "correct" pitch, undoubtedly saving the careers of many-a-terrible pop singer today (thanks?). Here's the wiki page for Auto-Tune, and here's a Nova Science Now Q&A with Dr. Hildebrand himself.

And it's all thanks to geophysics!

Cyclic subsidence and uplift in the Mississippi Delta

The Mississippi Delta is really one of those iconic depositional settings within sedimentary geology; when folks talk about deltas, consciously or unconsciously most people get a picture of that big, beautiful, stereotypical Bird's Foot protruding out into the Gulf of Mexico. And not without good cause, of course. From a purely aesthetic viewpoint, the Mississippi Delta is just damn pretty, especially from space, as evidenced by the Earth as Art Landsat image of the Mississippi Delta, below:



And scientifically, the Mississppi Delta has experienced a fair amount of study. Coleman (1988) provided a nice summary of the evolution of the Delta, demonstrating the complexity and extreme variability of the individual delta lobes. The image below is from Coleman (1988, his Figure 2 on p. 1000), and is the iconic illustration of how quickly the individual delta lobes of the Mississippi system switched location:


Coleman (1988) pointed out that the Mississippi system switches the locus of deltaic deposition on average every 1500 years. And keep in mind that each of those lobes covers ~35,000 km2, and is somewhere around 15-25 m thick. That's a lot of sediment in a pretty short amount of time! These pulses of deltaic avulsion and deposition have always been ascribed to the usual suspects in sedimentology: sea-level change, sediment supply changes, and subsidence in the delta.

Interpreting how these forcers interacted with the Mississippi delta system makes up a fair component of the literature, and has provided some interesting insights and entertaining arguments for many years. A recent paper by Blum et al (2008) has revealed a previously unknown driver of change within the deltaic system: cyclic uplift and subsidence driven by changing sediment volumes in the lower Mississippi valley.

Blum et al (2008) point out that the subsidence recorded along the Gulf Coast is different, depending on where you measure it. The figure below is from Blum et al (20088, their Figure 1 on p. 676). Notice how the Alabama and Texas coasts are pretty different from the Valley edge subsidence patterns. Of course, this has been recognized before. Tornqvist et al (2004) interpreted this signal as a result of ongoing glacio-isostaic adjustments. Using marshland peats as baselines, and correcting for the subsidence pattern, Tornqvist et al (2004) reconstructed a sea-level curve for the Mississippi delta.



However, an unexpected result of the Tornqvist model was a phase of "unacceptably high" rate of uplift in the peat benchmarks during the mid-holocene, corresponding to a mid-Holocene sea-level high. Tornqvist et al (2004) did not think that a phase of such large-scale uplift was vary realistic, and discounted it.

However, Blum et al (2008) may have identified a viable mechanism for rapid uplift and subsequent subsidence in the Mississippi Delta. Using the same data points and subsidence curves as Tornqvist et al (2004), Blum et al (2008) preformed a series of 1-D and 3-D isostatic modelling exercises that explain the observed uplift pattern (shown below is their Figure 3, on p. 677).



They interpret a phase of melt-water discharge during the last interglacial as having driven erosion and sediment removal out of the lower Mississippi Valley, followed by a period of Delta construction and valley filling. According to their isostatic models, this 2-phase erosion and then construction in the Lower Mississippi Valley produces up to 9 m of uplift that would effect 150 km of coastline! In other words, the sea-level signal recorded in the Mississippi Delta is a relative sea-level curve (of course), but in addition to having to deconvolve eustasy and sediment compaction, we also have to care about erosion and sedimentation in the attached lower Mississippi Valley as a cause of isostatically driven surface deflection! Pretty neat (and complicated)!

Blum et al (2008) point out that this isn't a Mississippi-only thing, either; deltas are attached to rivers, and in the big ones, we need to be aware of what the record of sedimentation and erosion is. In other words, changing the sedimentary volume drives not only the source-to-sink mass balance of clastic delivery, but can also have an effect on uplift and subsidence patterns in the system.

WORKS CITED:

Blum, M.D., Tompkin, J.H., Purcell, A., and Lancaster, R.R., 2008, Ups and downs of the Mississippi Delta: Geology, v. 36, p. 675-678.

Coleman, J.M., 1988, Dynamic changes and processes in the Mississippi Delta: Geological Society of American Bulletin, v. 100, p. 999-1015.

Tornqvist, T.E., Gonzalez, J.L., Newsom, L.A., Van de Borg, K., De Jong, A.F.M., and Kurnik, C.W., 2004, Deciphering Holocene sea-level history on the U.S. Gulf COast: A high-resolution recrod from the Mississippi Delta: Geological Society of America Bulletin, v. 116, p. 1026-1039.

Book Cliffs Channelform

Just a quick post of a nifty photomosaic from a roadcut, north of Price, UT. Behold (to quote The Bard: "Methinks that thou shouldst Clicketh, and lo! It doth have a greater size")!

A nice, simple, straightforward, channelform complex, with a couple-or-three accretionary macroforms forming the bulk of the channelform sandstone body. Note the differential compaction of the underlying coals in relation to the hefty sands that got emplaced over it!

"The Thing on the Fourble Board" - Halloween Geology!

It's Halloween again and, just like last year, I've got some geology- themed horror for you all to enjoy! As we all know, Science is the unholy pursuit of Knowledge That Man Was Never Meant To Know. And the MOST blasphemous of all sciences is geology, seeing as how we seek to understand the inner workings of untold epochs and the secret histories of Earth's unimaginably ancient past; I mean, that's a given, right? An exploration of the horrors that lurk in the dark recesses of the ancient Earth form the center piece of the radio play "The Thing on the Fourble Board", an episode of the horror show "Quiet, Please" from 1948 (downloadable from the link I just gave you).

The radio show takes place on an oil derrick (as evidenced by the the title: a "fourble" is a catwalk on a derrick that's four pipelengths high off the bushing) somewhere in Pennsylvania. After drilling deeper than anyone had ever drilled before, the rough necks come across...something from deep within the Earth.

Anyway, "The Thing on the Fourble Board" is probably one of the best, legitimately spooky pieces of horror radio out there (especially the weird vocalizations of the The Thing itself). And it takes place on an oil derrick (and, come to think of it, would be one hell of a "Safety Moment" back at Oil Company HQ). Anyway, sit back and enjoy some Halloween themed geology with "The Thing on the Fourble Board".

Happy Halloween!

Hawk vs Duck

Just a quick picture, taken from the loading bay in our department, of a hawk, enjoying a leisurely meal...

...actually, it's a little ominous, I reckon.

Kiwi Research Information Service

Lookit here! There's a one-stop gateway to all sorts of tasty, free (i.e., SOCIALIST), open-access research documents from a whole bunch of New Zealand research institutes anduniversities. This, of course, includes a fair bit of geology relating info, too. Nifty and convienient, which is what I would expect from Middle Earth.

Above: New Zealand Petroleum Research Institute

Remember when Science was rad?

Whew! A busy start to a semester, what with seminars and teaching and paper work and writing and oh yeah GSA isn't that far off so gotta get that talk done (well, started, actually). In amongst all this bullshit that you've got to put up with in schoolin', it's sometimes hard to keep sight of the reason why you got yourself into the mess that is grad school in the first place, you know?

There's a series of Op-Eds at The New York Times website, ostensibly for incoming freshmen, about how to get the most out of your college experience. All of them are written by big-wig academic types with hugely famous reputations, and some of the advice is a mixed bag (and some is hilariously predictable, given the writer, fer' instance: Harold Bloom thinks people should read the classics. Who'd a thought!?!). Anyway, there is kind of a neat one by Nancy Hopkins, on the excitement of Your Chosen Field, which is pretty good, I think.

Now get back to work!