Saturday, August 30, 2008

Sleepsuit

Look at this wacky thing! I was reading the July issue of the Mountain Gazette this morning (picked it up this summer in Colorado), and was struck by an ad for this thing called the "selk'bag." It's a sleeping bag that you can walk around in. Whoa... futuristic. And definitely kind of dorky. I want one!

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Watching weather

"Should we talk about the weather?"
-"Pop Song '89," Green, R.E.M. (1988)

Here's a satellite image of the Caribbean from early Friday morning:



Gustav's still moving northwest through the Caribbean, and set to enter the Gulf of Mexico by about midnight tonight, or early tomorrow morning. As you may have heard, everyone's getting ready for the worst-case scenario. Louisiana governor Bobby Jindal has already declared a state of emergency, and President Bush gave him a similar federal declaration. I'll be watching this one pretty closely over the next few days.

Another phenomenon that's manifesting itself over the coming days and weeks is the melting of the Arctic sea ice pack. As Al Gore noted in his speech the other night, the worst case scenario for melting of this sea ice has the Arctic ocean ice free sometime late in the term of the next president (but that's a worst case scenario). Certainly, the trend over time is towards less and less of the Arctic frozen. I follow the fluctuation of sea ice area on the website The Cryosphere Today (University of Illinois), which provides satellite data, graphs, maps, and animations of the areal extent of polar sea ice. Here, for example, is a graph showing the area of the Arctic Ocean covered by sea ice over the past year:



Last year, of course, it hit a record low, and there's still a few weeks to go before it starts freezing up again (mid-to-late September is the time of the minimum). Open Mind did an excellent post examining the trend here, although the pattern is also observable on this long-term graph from Cryosphere Today. Here's another one, from the National Snow and Ice Data Center at the University of Colorado, that gives a half-century of context to the graph above:


In case DC-area folks didn't hear about it, there's also been some recent flooding in the southwest. (Geoblogospheroids will be well aware of it already, thanks to excellent coverage from Lee Allison at Arizona Geology.) I swam in that canyon this summer, just above the confluence with the Colorado River, and so this caught my attention more than an equivalent story would have about flooding someplace I hadn't been.

In addition to these larger-scale phenomena, there's a more local kind of weather I'm watching too: it's actually started raining in DC, for the first time since I got back on August 1! (A perplexed Achenblog on this odd situation). Time to bust out the umbrella.

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Thursday, August 28, 2008

"Target Earth" article in National Geographic

Just now getting around to reading last month's issue of National Geographic, but it's a good thing I got to it yesterday rather than tomorrow -- because today's the day I talk about comets, asteroids, and meteors in Physical Geology class, and one of the topics that people always love to talk about is what happens when those big dumb space chunks smack into Earth.



The article's a good read, and illustrated with magnificent images, like this classic 1972 image of a fireball over Jackson Lake, Wyoming. That's the Tetons in the background. Check it out.

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Grimacing at Gustav

Gustav's going for the Gulf. This could be bad and will surely be a newsworthy topic over the next week. Other people have explored it better than I could, so I'll just link to them:

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Frost on Mauna Loa

Two weeks ago, my friend Lily took a hike up Mauna Loa. Lily teaches science at a middle school on the big island of Hawaii, and we became friends this summer at MSSE Dino Camp. I would think that living on the island of Hawaii would have some major disadvantages over time (my guess is that I'd get cabin fever living on an island), but you can also imagine that it would have some major advantages too.

In addition to live volcanic activity, surfing, exotic birds, and just general paradise-like conditions, add this to the list: climbing a tropical volcano to see giant frost crystals forming on top! Here's an image she took at sunrise, looking west over the summit caldera:

frosty_mauna_loa

Mauna Loa is the largest volcano on the planet Earth. Rising 5 kilometers from the Pacific seafloor to sea level, then an additional 4 kilometers to its summit, Mauna Loa has an estimated volume of 80,000 cubic kilometers! It's big.

Because it's so tall, the weather at the top is much colder than the tropical sultriness at the beachfront resorts. Lily and her hiking partner found this out when they camped out on top, and woke to find that overnight, giant crystals of frost had grown spike-like from the tops of the exposed cobbles and boulders of basalt. I don't have a sense of scale here, but I'm guessing these are a centimeter tall or so... Here's a close-up of the lower-left corner of the upper image:

frosty_mauna_loa_closeup

Pretty cool, eh? Literally. Maybe Hawaii has more variety than I had assumed. I think this calls for a field trip to investigate!

Thanks to Lil for sharing the photo!

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Wednesday, August 27, 2008

NOVA Caving trip Sept 13-14

NOVA students: This is a reminder that I'm going to be leading a two-day caving trip through the Annandale campus' Office of Student Activities. The trip runs from 8am on Saturday, September 13 to about 7pm on Sunday, September 14. We'll be going to a series of caves near Franklin, West Virginia: Trout, New Trout, Hamilton, and Keys. We'll also drive out to the Spruce Knob area to take in Stillhouse Cave and the Sinks of Gandy (which has a river flowing through it). I've led this caving trip many times over the past 15 years; it's awesome. Last time I took students there was for a GMU GeoClub trip in Fall 2005. Some photos from that trip are available here.

There is space for about 15 students on the trip. The trip has a cost of $35, which covers all food except for Saturday's lunch (bring that in a bag). For dessert on Saturday night at the campground, I'll be fixing Grandma Bentley's famous peach cobbler. If you're interested in going, please contact Jessie Zahorian in the Office of Student Activities at 703-323-3484 or jzahorian [AT] nvcc.edu. First come, first served! Other denizens of the geoblogosphere: sorry, but it's only open to NOVA students.

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Tuesday, August 26, 2008

NOVA needs geology instructors

Hey there! Do you (a) live in the DC metro area, (b) have an MS or a PhD in geology, and (c) want to teach? Well, NOVA might have a job for you. We encourage qualified applicants to send a c.v. and a brief letter of interest to Assistant Dean Craig Jensen at cjensen@nvcc.edu. Mainly we're recruiting for next semester, but we also had an instructor bail out on us this semester, so there is in fact a Monday/Wednesday afternoon class which will have to be cancelled unless we find someone ASAP.

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Geology Connects: August Accretionary Wedge

When I look back on my four years of undergraduate geology education, the one thing that strikes me as the most important thing I learned is the age of the Earth. It sent my mind reeling to recognize what a huge old planet I was on, and how ephemeral was my own species' time on it. I was a blip, a temporary arrangement of carbon, hydrogen, oxygen, and a handful of other elements that would last a while, and then disassociate. Material and energy passed into me, and out. This kinetic chemical phenomenon known as me would soon pass, and the Earth would keep turning. The human species would reach its zenith, then collapse (or evolve into something else), and the Earth would keep turning. The continents would rift and crash and the map of the Earth would soon be obselete, and the Earth would keep on turning. Climates change, meteors hit, "rivers shift, oceans fall, and mountains drift" (REM, 1985), and still the planet keeps on spinning, keeps on orbiting, keeps on keeping on.

The day I really realized the age of the Earth wasn't the day I heard "4.6 billion" in lecture. It was the day I sat there studying and grasped it internally -- it clicked that it was immensely, unimaginably old. My temporary human mind was a short-time-scale phenomenon, and it was impossible for this small cerebral system to get a grip on the true scale of the planet's age. While I would never really know (comprehend/appreciate) the age of my planet, I tapped into something fundamental that day. Looking back on it now, I'm reminded of John Playfair's words when his pal James Hutton took him to Siccar Point for the first time: "The mind seemed to grow giddy by looking so far into the abyss of time" (1805).

When I made that cognitive leap (by essentially realizing it was impossible for me to fully make the cognitive leap), I got stuck on geology. I connected to the study in a way I hadn't done before. Suddenly I was subject to a dizzying temporal vertigo, as if a layer of flooring had crumbled away leaving me gazing into a bottomless pit. The realization gave a whole new perspective on things, and it was exhilarating. It felt like one of the conversations when you're getting to know someone, and realizing that they are both intriguing and yet never completely knowable. It draws you in, connects you. Without getting too gushy, it's kind of like falling in love. I've been a geologist ever since.

As I learned more, both in school and on later peregrinations around the world, I found that geology was a great traveling companion. No matter where I went, geology was there with me, showing me new things, giving me insightful perspective. I was looking at the world through geology-colored glasses, and finding that it had a lot to show me. The world made more sense on an elemental level. Hills made sense; rivers made sense; mountains made sense. While I couldn't claim to fully understand any of these phenomena, I could claim a connection to them now that wasn't there before. They were no longer random in my mind; they had a place in the overall system, and it took geology to make me realize it.

So this perspective has stuck with me, and it's what inspired me to pitch "geology as a connector" as this month's Accretionary Wedge theme. (Newbies: the Wedge is a semi-monthly geoblogosphere carnival wherein different geobloggers contribute posts organized around a central theme.) I was curious about what I would get, and I didn't want to restrict my peers' submissions by specifying what kind of connections should be written about.

Sure enough, different people interpreted connection differently. Tromping around in the mountains doing geologic mapping yields more than insights into local structure and stratigraphy, as BrianR of Clastic Detritus discusses how his field work has connected him to the messy reality that is nature.

Jess at Magma Cum Laude is starting her first semester as a graduate T.A., and is going to employ a teaching technique that connected her to the pervasive nature of geology: everything that the Earth puts out for the purpose of assembling Oreo cookies. Something as simple as an Oreo can be the vehicle through which students realize the manifold ways they depend on the Earth every day.

Where are the boundaries between sciences? Is geology a subset of environmental science, or physics? Or both? How do we define the different parts of Nature that we study? Using a Venn diagram, Hypocentre at Hypo-theses explores the connections between geology and other sciences, particularly in the environmental realm.

Similarly, Mel uses a diagram to explore connections in her post at Ripples in Sand. How does geology connect to paleontology? Join Mel in looking at the taphonomic bridge. (And wish her congratulations on her wedding while you're at it!)

Joining the crowd in her first Accretionary Wedge post, A Life Long Scholar (at The Musings of a Life-Long Scholar) makes a connection between the very small and the very large. In trying to answer questions about massive tectonic plates, sometimes geologists must turn to little bundles of mass a few micrometers across. Check out her post to see how garnets can reveal the secret histories of the continents.

And then there are the personal connections. In Looking for Detachment, Silver Fox was the first one to submit a post on the "connection" theme with her description of how different members of the mining and exploration community connect to one another over time and space (Nevada, of course). How do Charles Manson, Kevin Bacon, and exploration geologists all fit together? Read her post to find out.

MJC Rocks of the Geotripper blog has contributed a real treat: an exploration of the connection of geologists teaching geologists through time. It turns out that his academic lineage goes all the way back to Agassiz and Cuvier! A pretty impressive consideration which will surely inspire the rest of us to investigate our own geologic pedigrees.

Finally, over at Harmonic Tremors, Julian shares a story of how his knowledge of geology led him to make a personal connection with one of his cinematic idols, director Brad Bird. If you've seen the Incredibles, you're familiar with Bird's high quality entertainment. When Julian heard that Bird was working on a movie called 1906 about the great San Francisco Earthquake, he wrote a letter to clear up some inconsistencies in the book upon which the movie is based. The talented director took the time to write back to Julian, thanking him for the "seismic tutorial."

Enjoy the various and sundry posts -- follow these digital connections to other geologists in other parts of the world, and feel connected to the larger community of earth scientists. Thanks to everyone who contributed. If I've missed anyone or if anyone wants to submit a late post, give me a shout or post a link in the comments.
________________________
References:
Playfair, John (1805). Transactions of the Royal Society of Edinburgh, vol. V, pt. III.
REM, (1985). "Feeling Gravity's Pull," Fables Of The Reconstruction, IRS records.

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Monday, August 25, 2008

Lockhouse 8 geology event


As I mentioned a while back, this weekend I volunteered to lead a geology event at the Potomac Conservancy's Lockhouse 8 River Center. The event was well attended: 37 people showed up, which is apparently the largest group they've had at one of these events all summer!

It continually impresses me how many people in DC are interested in geology. It doesn't seem as intuitive as if we lived in, say, Arizona. But these outreach events I do usually exceed my expectations in terms of attendance. There were also some excellent, insightful questions from the group. We discussed how the different physiographic provinces of the east coast provide information about the different "chapters" of the area's geologic story, and then we examined some actual rocks, to see details from the Piedmont chapter of the story.
One of the attendees took some photos, and posted them on his Picasa album:
http://picasaweb.google.com/eric.dahlstrom/GeologyOfTheCOCanalCallanBentley
(That's one of his above: I really like the panorama effect. Geologists on the left, Potomac River on the right, all part of one big picture.) Thanks for the photos, Eric!

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Granite, Uranium, Onion

The Onion's "American Voices" covered a recent issue (see here in the New York Times, for instance) that some people are paying attention to: radiation emitted by granite countertops.

Because granite contains some uranium (different levels in different granites), some folks are getting upset that their fancy, expensive granite countertops could actually be emitting radiation into their kitchens. But, as the article points out, it's not really all that much in the grand scheme of things.

One final note: the image used to illustrate the story (shown here) is apparently the exact same variety of garnetiferous granite gneiss that my father recently chose for his countertops, when renovating his kitchen! I'll have to bring the Geiger counter over there next time I visit...

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Woodcut block print of a tyrannosaur

I used to do a lot of woodcuts. Woodcuts are a kind of block printing, where you start with wood (usually basswood, or something else of medium hardness) and then carve away everything that you want to be white in the final print, leaving behind everything you want to appear black. Once the carving is done, ink your print and press it to a piece of paper, and you get a cool looking block print. The same thing can be done with linoleum, styrofoam, or potatoes.

Based on Googling my personal website, a design firm in Seattle recently contacted me to do a new series of woodcuts. Their client, a housing development in Washington state, wanted a squirrel mascot. So over the course of the past week, in addition to preparing for the fall semester, I busted out the chisels and ink roller. Here's the squirrel that I prepared for them:

squirrel

But carving the squirrel reawakened this particular creative urge in me. I like doing woodcuts! And I like thinking up my own material to carve. So in my spare time, I started this fellow, finishing him up yesterday afternoon as the sun dipped low in the western sky:

dino

He's sort of a juvenile, freaked-out, overweight, embryonic, stressy tyrannosaur. With an overbite. I like him because, artistically, he combines my interest in cartoons with my interest in block printing. (And of course, my interest in geology!)

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Sunday, August 24, 2008

New country list

Adding to the list of visitors' countries that I detailed halfway through the week, the last four days have brought in new visitors from: Iceland, the Palestinian Territory, Jordan, Latvia, Kuwait, China, the Netherlands, the Czech Republic, Turkey, Algeria, Thailand, Indonesia, the Canary Islands (Spain), Ireland, Taiwan (China), Panama, Nigeria, Pakistan, and Hong Kong (China). I think that brings us up to 56 total... Whoa.

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Friday, August 22, 2008

Connect! Accretionary wedge reminder

Just a friendly reminder that I'm soliciting posts for the August edition of the Accretionary Wedge (a geoblogosphere carnival).

Geobloggers, take some time over the weekend and let me know your thoughts on how geology serves as a "connector science." (Interpret however you want!)

I'd like to organize the Wedge on Monday the 25th, so please get your posts (link below in the comments section or send me an e-mail) by Sunday at midnight (or so).

Thanks. Again, I'm looking forward to hear what people have to say.

UPDATE: The FTP issue has been resolved, and I can again post to the blog, so watch for the Wedge to be published later today. Thanks for your patience.

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Driving through Wyoming

On Saturday, June 14, I drove from Fort Collins, Colorado northwest across Wyoming, ending up just west of Cody in Shoshone Canyon.

Here's a few photos I took along the way:

Hogbacks (or "incipient hogbacks?") north of the Interstate (not sure whether this qualifies as the Laramie Mountains or the Medicine Bow Range, or some other range altogether).
WY_travel_02
Regardless, what you're seeing here is what happens when tilted sedimentary strata are incised by streams. The stream valleys develop at regular intervals along the slope, and notch the sedimentary layers, which themselves have different resistances to erosion. As a result, these triangular-shaped slabs end up poking up along the flanks of the mountains (the Flatirons outside of Boulder, Colorado, are perhaps the best known example).

The Wind River Range appears in the distance. Seeing big bad mountains makes me happy.
WY_travel_04

Road trip man!
WY_travel_03

The Prius at the southern (upstream) end of Wind River Canyon, between Shoshoni and Thermopolis:
WY_travel_06

...And looking downstream (north):
WY_travel_07

Unconformity between Archean basement rocks and overlying Cambrian sandstone:
WY_travel_08

The Wind River:
WY_travel_09

An outcrop on the way north, somewhere south of Meeteetse. Got some cool green concretions here, and coasted downhill for more than ten miles:
WY_travel_05

Camp at the end of the day. This is at Buffalo Bill State Park, between Cody and the eastern entrance to Yellowstone (Sylvan Pass, subject of a photo I put up yesterday). The body of water seen here is the Shoshone Reservoir. I enjoyed a pleasant evening here of drinking wine, writing a letter, and watching grebes in the water.
WY_travel_10

Dark clouds came over later, hastening nightfall over the park. Note the addition of the rainfly to the tent. Turns out we just got a sprinkle, no real downpour.
WY_travel_01

Life on the road is (was) good. Months later, it makes me happy to look at these photos and think about rolling along across the great North American continent, checking stuff out, seeing new places. Classes start on Monday for me, and I'll be locked down in DC for a bit... a fair trade, it seems to me, if my job allows me to go out and see places like these during the summers.

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Thursday, August 21, 2008

Sylvan Pass, Yellowstone

yellowstone_ice_sign

...No kidding!

This photo was taken in early June, when I drove through Yellowstone for the first time this summer... there was still snow eight feet deep along Sylvan Pass at that time!

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Wednesday, August 20, 2008

Data deluge

A week ago today, I installed SiteMeter on this blog, to get a sense of who's visiting. I put a counter on a couple of months ago, and I've been somewhat astonished at the numbers it's telling me (which are supposedly individual IP addresses, not page clicks). I mean, really: more than 14,600 people reading NOVA Geoblog? How can that possibly be right?

So I installed SiteMeter to get a better handle on the data. This might be some pretty indulgent navel-gazing, but it's also astonishingly rich data. There is a huge amount of information that a service like SiteMeter collects about you every time you visit a website, and this experience has been eye-opening for me...

In the week since I installed SiteMeter, I've had 647 visits (unique hits, but some of these represent repeated visits by single individuals), and some of those people visited more than one page during their time on the site (a total of 1,097 page views in total over 7 days). The average number of visits per day is 91, but the average time people spend on the blog is only 1 minute and 30 seconds!

Check out a couple of World Maps of visitors to this blog in the past week. I can only display 100 visitors at a time, so here's Monday morning's map:

geoblog_visitors

The red dot was the last visitor at the time this map was generated, and the green dots are the nine previous visitors before that. The white dots are the remaining 90 to sum up to 100 total.

Here's today's map (again, "just" the last 100 visitors):

geoblog_visitors_2

Overall, in the past week, NOVA Geoblog has had visitors from Panama, Hong Kong, Korea, the Philippines, Austria, Spain, Iran, Switzerland, Mexico, Bulgaria, Hungary, Italy, France, Argentina, Canada, Malaysia, Japan, Australia, Norway, France, the U.K., Sweden, South Africa, Venezuela, Chile, Brazil, Russia, Finland, Portugal, Romania, India, Germany, Belgium, Israel, Denmark, Saudi Arabia, the United Arab Emirates, New Zealand, and Egypt. Whoa! Including the U.S., where most NOVA Geoblog visitors visit from, that's 40 countries in a week... I'm somewhat astonished.

SiteMeter generated a pie chart to show the relative proportions of these different locations:

SiteMeter gives you all kinds of crazy data. Here, for instance, are the last 20 visitors' entry pages (the first page they hit on visiting this blog):

1 http://nvcc.edu/home/cbentley/geoblog/labels/geology.html
2 http://nvcc.edu/home/cbentley/geoblog/labels/geology.html
3 http://nvcc.edu/home/cbentley/geoblog/2008/02/biofuels-cartoon.html
4 http://nvcc.edu/home/cbentley/geoblog/2008/02/totem-pole-tasmania.html
5 http://nvcc.edu/home/cbentley/geoblog/2008/08/promoted.html
6 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html
7 http://www.nvcc.edu/home/cbentley/geoblog/
8 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html
9 http://nvcc.edu/home/cbentley/geoblog/2008/02/riddle-of-cake-revealed.html
10 http://nvcc.edu/home/cbentley/geoblog/2008/08/is-georgia-in-europe-or-asia.html
11 http://nvcc.edu/home/cbentley/geoblog/2008/08/unconformities-of-grand-canyon-part.html
12 http://nvcc.edu/home/cbentley/geoblog/labels/geology.html
13 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html
14 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html
15 http://nvcc.edu/home/cbentley/geoblog/2008/08/is-georgia-in-europe-or-asia.html
16 http://nvcc.edu/home/cbentley/geoblog/2008/01/columnar-jointing-and-weathering.html
17 http://nvcc.edu/home/cbentley/geoblog/2008_02_01_archive.html
18 http://nvcc.edu/home/cbentley/geoblog/2008_02_01_archive.html
19 http://nvcc.edu/home/cbentley/geoblog/2008/01/life-during-anthropocene-time.html
20 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html

There are some trends here, but you don't need to puzzle them out on your own, because SiteMeter will do it for you. Here are the most popular pages over the past week that initially lured visitors to the blog (black number on left is the number of times visitors hit that page first):

13 http://nvcc.edu/home/cbentley/geoblog/2008/05/perspectives-on-coastal-tectonics.html
11 http://nvcc.edu/home/cbentley/geoblog/2008/08/beer-is-bad-for-science.html
8 http://www.nvcc.edu/home/cbentley/geoblog/
7 http://nvcc.edu/home/cbentley/geoblog/labels/geology.html
5 http://nvcc.edu/home/cbentley/geoblog/2008/08/is-georgia-in-europe-or-asia.html
5 http://nvcc.edu/home/cbentley/geoblog/2008_02_01_archive.html
5 http://nvcc.edu/home/cbentley/geoblog/labels/fossils.html
3 http://nvcc.edu/home/cbentley/geoblog/
2 http://nvcc.edu/home/cbentley/geoblog/2008/05/scary-map-du-jour.html
2 http://nvcc.edu/home/cbentley/geoblog/2008/08/accretionary-wedge-call-for-posts.html
2 http://nvcc.edu/home/cbentley/geoblog/2008/08/unconformities-of-grand-canyon-part.html
2 http://nvcc.edu/home/cbentley/geoblog/labels/msse.html
2 http://www.nvcc.edu/home/cbentley/geoblog/2008/05/chaiten-update.html
2 http://www.nvcc.edu/home/cbentley/geoblog/2008/05/shenandoah-np-corbin-cabin-area.html
1 http://nvcc.edu/home/cbentley/geoblog/2008/01/asteroid-news.html
1 http://nvcc.edu/home/cbentley/geoblog/2008/01/brrr.html
1 http://nvcc.edu/home/cbentley/geoblog/2008/01/columnar-jointing-and-weathering.html
1 http://nvcc.edu/home/cbentley/geoblog/2008/01/fault-photo.html
1 http://nvcc.edu/home/cbentley/...-during-anthropocene-time.html

Wondering about what browsers these visitors are using to access these pages? Turns out SiteMeter keeps track of that too (as well as what kind of monitor you're using, your internet service provider, and what you ate for breakfast!):


Where are these people coming from? What's the referring page that links them to NOVA Geoblog? Turns out SiteMeter can tell me that too! A lot of visitors were brought here by web searches, including a lot of image searches. People searched on Google or Yahoo for "biofuels cartoon," "totem pole tasmania," "unconformities in the grand canyon," "geoblog," and many more. Others were linked to my site from other geology blogs, and a few came from my NOVA website and my Blackboard courseware platform.

If this sort of stuff interests you (and I can't imagine why it should), you can explore details of each of these searches on the SiteMeter's "NOVA Geoblog" page (click on the SiteMeter icon below the counter in the right column, or click here).

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Tuesday, August 19, 2008

Beer is bad for science?

The Freakonomics blog draws our attention today to a new study suggesting that beer consumption and low publication records are correlated. Hmmm.

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Monday, August 18, 2008

Is Georgia in Europe or Asia?

In his "Achenblog" today, the Washington Post's Joel Achenbach discusses whether the former Soviet republic of Georgia is in Europe or Asia. A bit of geography to start your day.

Being a geologist rather than a geographer, I'm of the opinion that it's in Eurasia, but no one's asking me...

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Saturday, August 16, 2008

Promoted

As of today, I'm now an Assistant Professor of Geology at NOVA. (I used to be an Instructor.) Yee-ha!

The Rank ladder at NOVA has four rungs: Instructor, Assistant Professor, Associate Professor, and Professor. With positive evaluations and the credits I accrued from my MSSE program, I qualified this summer to climb up a step. (NOVA does not have tenure; just contracts of increasing duration.) In another couple years, I'll be able to apply for promotion to the rank of Associate Professor, but I won't be able to make the jump to full Professor unless/until I get a PhD.

I'm a bit torn about the PhD: I feel like it's a research degree, whereas I'm not doing research in my job at NOVA. I'm an educator. And it's a fair bit of effort, that whole PhD thing: getting a degree specializing me to do research that I don't do. On the other hand, it sure would be nice to be finished with explaining to people that I'm not a doctor. And I'm sure it would help inform my teaching -to some extent- it's just a question of gains versus effort.

Time will tell; I get the feeling I'm going to start itching for another degree come next summer...

Anyhow, for the moment, I'm pleased with the validation of being promoted. Yesterday, I updated my main NOVA webpage to reflect the change. ...And the moustache.

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Enceladus

Every now and again, I like to post an image that just speaks volumes. Check this one out, of Saturn's moon Enceladus. Wow! What a beauty. This photograph was taken on Monday by the Cassini spacecraft. Enceladus may host liquid water below the surface, since it has geyser-like features near its south pole. There are only three places beyond the asteroid belt where eruptions have been seen: Enceladus, the jovian moon Io, and Neptune's moon Triton. Enceladus is only a few hundred miles wide; These fractures are about 1000 feet deep.

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Friday, August 15, 2008

Geotimes becomes EARTH

Starting with next month's issue, the magazine Geotimes will change its name to EARTH magazine.

Why? Listen to Pat Leahy give AGI's reasons in a video on Geotimes' website.

I gotta say -- this is a smart move. How many people, browsing the racks at Barnes & Noble, are going to pick up a rag called "Geotimes"? It's a pretty dorky name. On the other hand, how many people are going to pick up a magazine called "EARTH"?

Whoa... Major customer expansion, I'll bet. I'm curious to see how much it takes off.

The magazine is re-inventing itself in several ways, not just switching out the masthead. I noticed in the June issue, they started featuring a crossword puzzle, and next month's issue will be the first to feature my monthly cartoon. It's also going to be longer.

Change isn't just a political word this year...

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Three-dimensional trilobite images

The coolest research website you haven't seen is on Whitney Hagadorn's page at Amherst.

With undergraduate student Martha Buck, he's taken pyritized trilobite fossils from the upper Ordovician Frankfort Shale ("Beecher's Trilobite Beds") near Rome, New York, and X-rayed them. A series of X-ray images taken at different angles have been spliced together into a movie, which gives a real sense of the three-dimensional nature of the fossil, as well as insight into the finer details of its anatomy like legs and antennae, which don't often fossilize:

This is Triarthrus eatoni. You can replay the movie by refreshing the page on your Internet browser. The full suite of images is available on this page. Check it out!

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Thursday, August 14, 2008

Upcoming events in DC geology

Fellow DC metro area residents -- there are a bunch of geology events coming up in the next couple of months that you may be interested in. Everything* listed here is free and open to the public.

Next Sunday, August 24, I'll be leading an event called "Geology Along the C&O Canal," at the Lock 8 River Center from 10am until 11am. My plan is to give an overview of the Appalachian mountain belt, then focus on the Piedmont "chapter" of that story, using local outcrops to illustrate the rock types produced. I'm not sure if you need to reserve a spot or not; Call Bridget Chapin at the Potomac Conservancy (number at link above) to inquire about details.

Friday, September 5: "Geology Along the Billy Goat Trail," I'll lead this hike along the famous Billy Goat Trail, examining its exquisite display of metamorphic geology and geomorphology. 12:30pm-4:30pm. Reserve a spot through the good folks at the Great Falls Tavern Visitor Center.

Wednesday, September 10: first Geological Society of Washington meeting of the fall. Beer served at 7:30pm, and the formal program begins at 8pm. At the Cosmos Club in Dupont Circle.

Saturday, September 20: I'll be leading my "History Before History: the Geologic Saga of Washington, DC" walking tour as part of Walkingtown, DC. The tour runs from 1pm until about 4pm, and involves about 2.5 miles of walking from Adams-Morgan to Georgetown. Limit of 30 people; interested walkers should reserve a spot with Cultural Tourism, DC, the nonprofit group that sponsors Walkingtown, DC each spring and fall.

Sunday, September 21: For those who can't make it Saturday, I'll again be leading my "History Before History: the Geologic Saga of Washington, DC" walking tour as part of Walkingtown, DC. The tour runs from 1pm until about 4pm, and involves about 2.5 miles of walking from Adams-Morgan to Georgetown. Limit of 30 people; interested walkers should reserve a spot with Cultural Tourism, DC, the nonprofit group that sponsors Walkingtown, DC each spring and fall.

Wednesday, September 24: Another Geological Society of Washington meeting, but I'll be delivering a talk at this one. My talk's title is "Rise of the geoblogosphere."

Sunday, October 5: I'll be delivering a talk called "A Geologist's Perspective on Climate Change" at the Chinn Park Regional Library in Woodbridge, Virginia. 2pm-3pm.

Friday & Saturday, October 10-11: The Virginia Geological Field Conference, in Marion, VA. "Geology of the Saltville and Pulaski Fault Blocks" is this year's topic. *This is the one item on the list that is not in the immediate DC metro area, and also the one item on the list that costs money -- registration is $45 for professionals, $20 for students. Transportation, lunch, and guidebook will be provided. See more details on the website. If you're interested in comparing and contrasting two Valley and Ridge fault blocks shoved westward during Alleghenian mountain-building, this might be of interest to you.

Thursday, October 23: the Earth's birthday, according to James Ussher. 4004 BC to 2008 AD; does that make it 6012 years old? Or is it 6011 years old, since there was no year "0"? Tricky... Regardless, I'll be serving lithosphere/asthenosphere cake/pudding to NOVA students in celebration of the day. (I posted on visiting Archbishop Ussher's church here.)

Wednesday, October 22: Another GSW meeting. Same time, same place, but this time I'll be back where I belong: in the audience.

Friday, October 24: "Geology Along the Billy Goat Trail," I'll lead this hike along the infamous Billy Goat Trail, examining its exquisite display of metamorphic geology and geomorphology. 12:30pm-4:30pm. Reserve a spot through the good folks at the Great Falls Tavern Visitor Center.

If you're into geology and you'll be around, I hope you'll join us on one or more of these events.

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Geological excursion in Silver Spring, Maryland

Yesterday morning, I took a jaunt with a local amateur geologist, Owen P., to go look at some outcrops in streambeds in and adjacent to Silver Spring, Maryland.

Owen wanted me to look at these surfaces, our local unconformity between foliated metamorphic rocks of the Piedmont below, and unconsolidated sediments of the basal Coastal Plain above (cell phone for scale): slvr_sprg_crk_uncnf_5001
The lower rocks are metagraywacke schist of the Sykesville/Laurel Formation (different aspects of the same thing, as far as I am concerned, and not worthy of two different formation names). They were metamorphosed during the Taconian ("Taconic") Orogeny, ~460 million years ago. These rocks were then eroded, and new sediments deposited on top of that eroded surface -- this is an unconformity like the ones I posted about over the past couple of days out in Wyoming and Arizona.

My host thought the layer above the unconformity might be tsunami deposits associated with the Chesapeake Bay bolide impact at 35.5 million years ago. However, that's not what I saw. Instead, the high proportion of angular quartz, and the fact that it was clast-supported rather than matrix supported, suggested to me that the upper layer was a gravel deposit from this very stream. It was good for me to see such a collection of angular clasts atop the unconformity -- on hilltops in DC, I'm used to seeing the Potomac Formation in this position. It's a Cretaceous-aged river deposit, with a real mix of sand, clay, and well-rounded (mainly quartzite) cobbles.

Another look (with cell phone for scale):
slvr_sprg_crk_uncnf_6001

After I explained why I didn't buy the tsunamite hypothesis, but encouraged him to keep looking, Owen took me to another cool location, on Northwest Branch (a creek) just outside the Beltway at Burnt Mills Park. Here's a location map:


There, we found an outcrop of migmatitic metagraywacke very reminiscent of the one I visited on Four Mile Run in Arlington, VA, in March of this year. Cutting down, Northwest Branch has exposed a complex of clearly metasedimentary, clearly granitic, and not-so-clearly transitional migmatitic rocks. It's pretty cool, and not only because some of the potholes went all the way through the rock, making wormhole tunnels that a geologist can (and will) crawl through...
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I found a couple of cool igneous contacts. Here's a dike of granite cutting through metagraywacke. I like this outcrop because it shows that these things are in fact filled-in cracks, and cracks have a propagating edge, a tip. Most granite dike exposures don't show this fracture edge, but this one does. In spite of the graffiti, it's a good look at that process caught in the act.
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And here's a nice example of cross-cutting relationships. Host metagraywacke (notice the pebble-sized clasts of various lithologies in the upper left) is cut by two granite dikes: first a finer-grained, darker-colored one, and then by a coarser-grained, lighter-colored one. Beauty!
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Thanks to Owen for showing me these outcrops -- I appreciate the interest and the invitation!

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Accretionary Wedge: Call for posts

It's been a while since the last Accretionary Wedge, and the fact that I volunteered to host dropped off my radar... but I was reminded yesterday that August is my month!

So, I hereby solicit the geoblogosphere's thoughts on how geology serves as a 'connector' science. I'm interested in a bunch of posts connected by the theme of connection.

This could work a couple of ways: one is that you, by studying geology, feel more connected to the Earth, or to the universe, or to deep time, or some such. By being scientific, the practice of geology can lead you to places, or insights, that give you a very non-scientific sense of belonging, as being a manifestation of geological processes and circumstance. Sometimes this can be pretty profound; I've felt it strongly, and my guess is that I'm not the only one.

You could also interpret 'connection' differently: like how geology connects other disparate branches of inquiry together (we're a pretty multidisciplinary lot, after all). Geologists utilize chemistry, physics, biology, meteorology, and astronomy to get a better handle on our chosen planet of study... how do those connections play out? What are some examples?

A third possible read on 'connection' might be a post on the nature of the geoblogosphere. Though early-adopter Andrew started in 2003 (!!) and Ron started in early 2005 (!), a lot of geobloggers started writing in 2007 or this year. It might be apropos to have some meta-reflection on the nature of the connections we're all forging across cyberspace.

You can come up with any other ideas, too. I just offer these three interpretations as possible approaches to the connection theme. Feel free to think outside the box though -- that keeps it interesting.

Because I'm late in getting this going, the turnaround time will be pretty quick. Let's have them all by midnight next Sunday, August 24. That gives writers a week and half. Once they're in, I'll package them up and post them on Monday the 25th (the day before my first day of classes for the fall semester). Okay? Okay.

Thanks -- looking forward to reading what people have to say!

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Wednesday, August 13, 2008

Unconformities of the Grand Canyon, part deux

As a follow-up to yesterday's post on the "Great Unconformity," today I offer a few more shots of unconformities in the Grand Canyon, including (at the end), an angular unconformity...

First, here's a close-up of the contact between the Vishnu Schist and the Tapeats Sandstone:
gc_unconformity_K

Slightly blown-out because I was shooting into the sun, and the outcrop was in shadow, but that's why God invented Photoshop:
gc_unconformity_I

Same thing, but with the direct light, it's texture (rather than color) that allows you to discern the difference between the two rock units:
gc_unconformity_H

The Great Unconformity is visible here, with a boatload of river rafters for scale:
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Same thing:
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Same thing again...
gc_unconformity_E

Okay, here's something different. A waterfall shot. People apparently love waterfalls. Every place I went this summer with a waterfall, there were oodles of folks gathered around, and much flapping of camera shutters. I must be dim, because I kind of don't get it. Water flows downhill... What's the big deal? Anyhow, here the waterfall actually shows us something interesting: note where it emerges from:
gc_unconformity_J
That's right -- from the unconformity. Apparently, this is due to the stubborn resistance of the crystalline basement rocks, which are tougher to erode into than the overlying sandstone. The creek cut through the sandstone, but hasn't yet cut through the Vishnu Schist and Zoroaster Granite. However, the Colorado River has, and as the creek flows into the river, there's a difference in the elevation of the two bodies of water. Hence, the waterfall.

I went for a pretty amazing swim in the pool at the base of this fall: the water was cool and bracing, and the wind created by the waterfall was amazingly powerful, actually blowing swimmers downstream! Just the thing after a hot hike.

Lastly, a different aspect of the same unconformity, also seen in the Grand Canyon. Don't look in the foreground, but high up on the distant ridge. This one is an angular unconformity, with sedimentary rocks below the ancient erosional surface as well as above.
gc_unconformity_D
In this case, the angular unconformity separates the Grand Canyon Supergroup from the Tapeats. The Tapeats, as we've seen, is Cambrian (~543-488 million years old). The Grand Canyon Supergroup (1.25 billion to 825 million years old) was laid down on the basement rocks first, then faulted and tilted 15 degrees. These tilted blocks were then eroded. On many, the Grand Canyon Supergroup was totally burnished away, re-revealing the underlying basement rocks. In the more down-dropped blocks, however, little protected packages of the Supergroup were preserved. When sea level rose anew in the Cambrian, it deposited the Tapeats Sandstone. In some places, the Tapeats sand was laid down on granite and schist, and in other places on these tilted layers of the Grand Canyon Supergroup. Same erosional surface; different rocks below it in different locations.

Here's a Flash animation showing the various steps it took to put the Grand Canyon together, including the erosion that gave rise to these various unconformities.

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Tuesday, August 12, 2008

Some great unconformities

This summer, I saw "the Great Unconformity" in a couple of locations.

An unconformity is a break in the local geologic record -- a period of time which elapsed without being recorded by the deposition of rock units. Often unconformities mark places where erosion has erased part of the local rock record, but sometimes they just mark periods of non-deposition. (Analogy: You can get a blank page in your diary two ways. You can either take a day off from writing, or you can write that day's entry and then later go back and erase it. Either way, you end up with a day going by and no journal entry.) People call the major break between metamorphic and igneous "basement" rocks and overlying sedimentary layers the "Great" Unconformity, though it's not the same age everywhere. It's just shorthand, really.

Anyhow, here it is in the Grand Canyon (photos provided below are both unadorned and annotated versions):

unconformity_01

unconformity_02

Give or take, there's about 1.2 billion years missing along this ancient erosional surface. Intuitively, this probably makes sense, since metamorphic rocks like schist and 'distilled' intrusive rocks like granite are characteristics of mountain belts, where they form at depth. In order to get those interior-mountain-belt rocks to the surface takes lots of erosion over lots of time (though not necessarily that long -- in DC, for instance, we have interior-mountain-belt rocks exposed that 'only' took 360 million years to make it to the surface). In the above photos, the metamorphic rocks and granites below the unconformity formed about 1.7 billion years ago, during the Mazatzal Orogeny, and the sedimentary layers on top (both quartz sandstones) were deposited in the Cambrian period, about 543-488 million years ago. They represent passive margin sedimentation along an ancient transgressive seashore, something like modern day beach sands along the east coast of North America. So, to get something like the Great Unconformity, take something like coastal Maine (Acadia National Park, say), and bury it beneath something like Virginia Beach.

And here "it" is again, in Wyoming's Wind River Canyon (between Thermopolis and Shoshoni):

unconformity_03

unconformity_04

A zoomed-in look at this same outcrop:

unconformity_05

unconformity_06

This time, however, the rocks below the unconformity are much older* metamorphics (schist & amphibolite) and granite. According to Maughan (1987), these are the oldest rocks exposed in Wyoming, having formed about 2.9 billion years ago. They were then metamorphosed at 2.75 billion years ago. These truely ancient rocks (Archean) were then eroded and exposed at the surface, where quartz-rich sand was laid down atop their burnished roots. Aside from the difference in the age of the underlying basement rocks, the story is very similar to the one at the Grand Canyon.

* Thanks very much to Kim, who pointed out my error in under-stating their age in an earlier, more-poorly-researched version of this post.

Reference:
Maughan, E.K. (1987) "Wind River Canyon, Wyoming." In: Geological Society of America Centennial Field Guide - Rocky Mountain Section. S.S. Buess, ed. p. 191196.

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Monday, August 11, 2008

Illustration page updated

I spent a fair bit of today updating the "Scientific Illustrations" page on my NOVA website. I'll be adding a few more images there in the next week or so, including another commissioned set, but I figured I'd mention it here now, since I've practically gone cross-eyed working on it all day.

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Igneous contacts of Boulder Canyon

Today: I offer some photos I took in Boulder Canyon, Colorado, in June. These are all igneous rocks exposed in the Precambrian 'basement' rocks, brought to the surface by the Laramide Orogeny.

Directions: Drive to Boulder; go west up the main canyon into the Rocky Mountain Front Range.

Location map:


Granite pegmatite:
boulder_cyn_01

Contact! Granite pegmatite meets granodiorite:
boulder_cyn_07

Contact! Granite dike cutting across granodiorite (with one small mafic xenolith):
boulder_cyn_08

Contact! Mafic xenoliths afloat in granodiorite:
boulder_cyn_04

Put the previous two pictures together, and what do you get? My favorite outcrop of the whole excursion... Contact contact! A granite dike cutting across mafic-xenolith-bearing granodiorite. This would be a good practice photo for introductory level students to establish relative ages of the three different rocks shown:
boulder_cyn_05

Contact! More prosaic, but high-contrast... Granite meets basalt:
boulder_cyn_02

Epidote vein (Without any good reason, I love the color of epidote):
boulder_cyn_03

My Prius parked on the side of Boulder Canyon Drive:
boulder_cyn_06

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Sunday, August 10, 2008

Sauropod tracks at Dinosaur Ridge, Colorado

Brontobulge_1Here's a few photos from the terrific drive-through geology exhibit called Dinosaur Ridge, near Morrison, Colorado (type locality of the Morrison Formation).

On the advice of my friend Michelle, I made a special detour to check out the area on my drive out west in June. It was worth on many levels, but my favorite part of the array of neat geology was this section, where you can see three-dimensional cross sections (if that's not an oxymoron) of sauropod footprints.

The idea is that when these sediments were wet and pliable, adult Apatosaurus (or a similar brontosaur) walked on by, sinking down into the wet sand and mud. Layers of sediment beneath were compressed (as if beneath a dropstone) and then a later deposit of sand filled in the "brontosaur bulges," preserving them. Now they are weathering out of the Dakota Hogback in relief!

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