Last year's president of the Geological Society of Washington, Bill Burton of the USGS, is the author of today's Earth Science Picture of the Day (EPOD). It shows Mount Redoubt erupting an ash plume amost a year ago. Go on over and check it out.

Labels: blogs, gsw, volcano, websites

Presidents past (and one future) gathered for dinner in the Cosmos Club before the Presidential address of Bill Burton, hours before he joined their ranks. From left: incoming president Jay Kaufman, John Slack, Dave Stewart, Peter Lyttle, Jane Hammarstrom, Rich Walker, Roz Helz, George Helz, about-to-be-past president Burton, Dave Applegate, Doug Rankin, Nick Woodward, Doug Rumble, Dick Fiske, and Brooks Hanson. Photo by Mary Horan. Make bigger by clicking here.

Labels: gsw

Wednesday, December 9, 2009: 1437th Meeting


Refreshments start at 7:30 p.m. The formal program starts at 8:00 p.m.
Meetings are held at the John Wesley Powell Auditorium
2170 Florida Avenue NW, Washington, D.C. (directions)

Labels: appalachians, dc, gsw, meetings, plate tectonics

Wednesday, November 4, 2009
1436th Meeting

One hundred thirty years of cartography at the USGS.
Will R. Stettner, U.S. Geological Survey, Reston

The Deep Carbon Observatory.
Russell Hemley, Geophysical Laboratory, Carnegie Institution of Washington

The Galapagos microplate revealed.
Deborah K. Smith, National Science Foundation & Woods Hole Oceanographic Institution

Refreshments start at 7:30 p.m. The formal program starts at 8:00 p.m.
Meetings are held at the John Wesley Powell Auditorium, Cosmos Club
2170 Florida Avenue NW, Washington, D.C. (nearest Metro is Dupont Circle)

Labels: gsw

Last night on my flight from DC to Portland, there were five GSW members ... About one-twelfth of the population of Wednesday's meeting! Plus I ran into the geologist from Blue Ridge Community College and a grad student from Virginia Tech. Cool!

Labels: gsw, meetings, oregon

First Geological Society of Washington meeting of the new academic year
September 23
http://www.gswweb.org/
Dupont Circle, Washington, DC

Virginia Region of the National Speleological Society caving convention (but without the caving)
September 25-27
http://www.varegion.org/var/events/FallVAR/FallVAR.shtml
Battle of Cedar Creek Campground (Route 11, between Strasburg and Middletown, Virginia)

New York State Geological Association meeting
September 25-27
http://www.newpaltz.edu/geology/nysga.html
New Paltz, NY

Virginia Geological Field Conference
October 2-4
http://web.wm.edu/geology/vgfc/2009.php
Big Meadows, Shenandoah Nat. Park, VA

Labels: caves, gsw, new york, shenandoah, structure, virginia

The Smithsonian's National Museum of Natural History, Department of Mineral Sciences invites the museum community to a memorial service commemorating the life contributions of Tom Simkin, the founding director of the Smithsonian's Global Volcanism Program. Simkin also served as president of the Geological Society of Washington. A memorial program will be held at Baird Auditorium on Tuesday, September 8 at 10:30 AM, followed by a reception in the Executive Conference Room. We welcome your attendance. Please send your RSVP (yes only) to Sally Kuhn Sennert (KUHNS@si.edu) by 1 September to help us make catering estimates for the reception.

Labels: gsw, museums, smithsonian, volcano

Paul Hoffman is speaking next Wednesday (April 22) at the Geological Society of Washington; I've just recieved word that his topic has changed from Snowball Earth to "The Pleistocene glacial controversy and the discovery of climate warming and crustal dynamics." I'm curious to see what Hoffman has to say about the 160-year old controversy as to whether there had been recent "Ice Ages," and how that relates to his currently-controversial ideas about the Snowball. Whatever he says, it's likely to be thought provoking.

Labels: geologists, glaciation, gsw, ice, pleistocene, science and society, snowball earth

GSW Spring Field Trip: Sunday, May 17, 2009

The Potomac Gorge: An Extraordinary Meeting Place of Geological and Biological Diversity

Led by: Tony Fleming, Natural Areas Geologist, and Gary Fleming, Vegetation Ecologist, Virginia Department of Conservation and Recreation

The Potomac Gorge between Great Falls and Georgetown is recognized as one of the most biologically diverse sites in the eastern United States, with an unusually large concentration of rare flora, fauna, and natural communities. For more than a century, the gorge has also enjoyed an iconic reputation as the region's premier geological area, both for its exceptional exposures of Piedmont bedrock and the complex tectonic history they reveal, and for the natural fluvial cycle of flood disturbance that still operates on the Potomac, the only Fall Zone river of its size whose flow is not altered by dams. Geology and ecology converge on this field trip, as we visit two sites where geologic processes exert a powerful influence on the distribution of unusual natural communities. At Turkey Run Park, we will hike past steep boulderfield communities and regionally rare sugar maple/mixed mesophytic forests more typical of New England, here growing on soils weathered from basic intrusive rocks in a cool microclimate created by processes driven by Pleistocene glaciation and the ongoing southward migration of the Potomac Valley. Chain Bridge Flats, by contrast, is a unique flood-scoured bedrock terrace hundreds of hectares in size that displays a complete ecotone of communities adapted to progressive changes in the form and intensity of natural flood disturbance as one approaches the river. Among these are disjunct, prairie grasslands containing calcium-loving plants more typical of the Midwest and Great Lakes. This site also is the largest and cleanest exposure anywhere in the Piedmont of the Sykesville Formation, the enigmatic and often inscrutable submarine trench deposit from the Taconic subduction zone that makes up much of the local bedrock. Here, a phenomenal array of textures, exotic inclusions, mega stratification, volcanic detritus, and metamorphic features can be seen together at a clarity and scale unlike anywhere else, providing insights into the origin of this enormous sedimentary melange.

Key Topics: Ecogeology; Georgetown Intrusive Suite; Sykesville Formation; Pleistocene and Holocene history of the Potomac Gorge; weathering, ground water, and nutrient cycling; flood frequency and dynamics

Field Trip Details: Hike departs promptly at 9:30 AM from lot C-1 at Turkey Run Park, and will follow the Potomac Heritage Trail towards Dead Run, returning to the parking lot by around noon. Eat lunch at the picnic area overlooking the old soapstone quarry at Turkey Run, before driving across the river to Chain Bridge Flats. Afternoon hike will depart around 1:30 from the parking area on Clara Barton Parkway immediately north of Chain Bridge, and will follow the towpath and ACE spillway out to the flats. Return by 4 PM. Expect spring wildflowers, poison ivy, some steep grades at Turkey Run, and rough terrain involving scrambling on rocks at Chain Bridge Flats. Sturdy footwear is a must. Bring lunch, snacks, and water. Restrooms are available at Turkey Run Park, but not at Chain Bridge Flats.

Questions? Contact Bill Burton at bburton@usgs.gov

Labels: field trips, gsw, piedmont, plants, rivers

Geological Society of Washington: Meeting 1432
Wednesday March 25, 2009

• Andrew Todd, US Geological Survey, Denver, Colorado - Abandoned Mines and Trout: The Interaction of Geochemistry, Metal Bioavailability, and Stream Ecology.
  
• Ian G. Macintyre, Smithsonian Institution, Washington, DC - The Almost Total Loss of Acropora palmata from Shallow Waters off Barbados, West Indies, Initiated by Catastrophic Destruction of a Major Bank-Barrier Reef off the Southeast Coast.
  
• Thomas J. Casadevall, U.S. Geological Survey, Denver, Colorado - Lusi: Long-lived Mud Eruption near Surabaya, Indonesia.

John Wesley Powell Auditorium, Cosmos Club
2170 Florida Ave NW
Washington, D.C.

Refreshments 7:30 pm; Meeting 8:00

Future meetings 2009: April 22 (Bradley Lecture); Sept. 23; Oct. 14; Nov. 4; Dec. 9.

Labels: environmental, fish, gsw, meetings, mining, reefs, volcano

The Geological Society of Washington now has a Wikipedia page, thanks to society historian Jeff Grossman (USGS). Check it out; add to it.

Labels: gsw, websites

GEOLOGICAL SOCIETY OF WASHINGTON : Meeting 1430

John Wesley Powell Auditorium, Cosmos Club, 2170 Florida Ave N.W., Washington, D.C.

Wednesday, 25 February 2009; Refreshments 7:30 pm; Meeting 8:00 pm
_____________________________________________________

Julie O'Leary, Carnegie Institution (DTM): Water storage and transport in the mantle: constraints from the H isotopic composition of ocean-island basalts

Jeff Pigati, US Geological Survey (Denver): Snails, cienegas, and the science of wetland deposits in the American Southwest

Barbara Anne am Ende, The Aerospace Corporation: Is thermal imaging practicable for finding caves and abandoned mines?

Labels: gsw, meetings

It was announced at Wednesday's Geological Society of Washington meeting that this year's Bradley Lecture will be delivered by Paul Hoffman, Emeritus Professor of Geology at Harvard University. The lecture is scheduled for the evening of April 22, starting at 8pm at the Cosmos Club.

Dr. Hoffman is best known for his work promoting the "Snowball Earth" hypothesis. It ought to be an exciting evening of geology!

Labels: geology, gsw, meetings, snowball earth

Wednesday 11 February 2009; Refreshments 7:30 pm; Meeting 8:00 pm;

the John Wesley Powell Auditorium

2170 Florida Avenue NW, Washington, D.C. 20008

Featured speakers:

Laurent G. J. Montesi, University of Maryland College Park - Cutting through the plate: rift interaction at the Galapagos triple junction

Marianne Guffanti, U.S. Geological Survey (Reston) - Volcano Hazards Revealed: Three Decades of Nature's Lessons for Applied Volcanology Cheryl Lewis Ames, Smithsonian National Museum of Natural History - Species composition and distribution of shrimps at cold, methane-bearing, hydrocarbon seeps in the northern Gulf of Mexico

Andrew Johnston, Center for Earth and Planetary Studies, Smithsonian National Air and Space Museum - Talking about the science of climate change with general audiences

Labels: gsw, meetings

Labels: antarctica, astronomy, australia, basalt, gsw, hadean, igneous, isotopes, meteors, minerals

A friendly reminder about tonight's meeting of the Geological Society of Washington:

Labels: gsw, meetings

Wednesday, January 21, 2009
1428th Meeting of the Geological Society of Washington

Robert Gagosian, Consortium for Ocean Leadership: A new paradigm for geosciences research funding.

Elizabeth Eide, Board on Earth Sciences and Resources, The National Academy of Sciences:
Geology, energy, and environmental policy at the coastal margins of the northern North Atlantic.

James Day, University of Maryland, College Park: Evidence for evolved crust formation in the early solar system.

Refreshments start at 7:30 p.m. The formal program starts at 8:00 p.m.
Meetings are held at the John Wesley Powell Auditorium 2170 Florida Avenue NW, Washington, D.C.

Labels: gsw, meetings

A special request from my fellow GSW member Nora Noffke (Old Dominion University), about a site in South Africa that Chris Rowan blogged about in May of this year:

The scenic Wit Mfolozi River Gorge in South Africa displays unique and spectacularly preserved sedimentary structures caused by microbial mats that colonized a sandy coastal area that are 3 billion years old. A comparison with modern microbial mats in a similar setting today suggests that the mat-constructing microbiota may have been cyanobacteria, possibly the oldest known in Earth history (GSA Today, October 2008).

In collaboration with the Society for Sedimentary Geology (SEPM), the Geological Society of America (GSA) and as part of the Year of the Planet Earth (IYPE), the Geological Society of South Africa (GSSA) is establishing the "Wit Mfolozi River Area" as a Geoheritage Site. This Geoheritage Site will serve visiting scientists, students and the interested public in leaning more about the Archean world and Earth's earliest life.

With the support of funds raised around the world, GSSA will set up the logistical and administrative infrastructure necessary to preserve and make this site available to all. This includes, for example, the construction of secure access to the site, installment of signs explaining the details of biogenic sedimentary structures at different spots in the outcrop and also measures to protect the site from damaging flooding by the river.

For further information about the site contact Roger Price (Geosite Conservation Committee, GSSA - rprice@geoscience.org.za), Nora Nofke (Old Dominion University and GSA Division of Geobiology and Geomicrobiology - nnofke@odu.edu) or Wesley Hill (GSA - hill@geosociety.org).

For donations to the fund for the site please contact Theresa Scott (SEPM - tscott@sepm.org).

Thank you very much,
Nora Noffke

Labels: action, africa, blogs, field trips, gsw

Yesterday was the Geological Society of Washington's fall field trip. A group of about twenty of us went down to George Washington Birthplace National Monument, a stretch of land in the Virginia Coastal Plain, about an hour east of Fredericksburg. The trip was lead by Wayne Newell of the USGS in Reston and Rijk Morawe of the National Park Service.

Here's a map of the Monument, adjacent to a small bay formed as the valley of Popes Creek flooded with post-glacial sea-level rise (essentially the story of the entire Chesapeake Bay in miniature):


Wayne and Rijk are studying the coastal processes here in an attempt to use the Popes Creek as an analogue for Chesapeake Bay processes in general. One of the reasons they really like it is because unlike other small bays in the area, it has a spit (almost a baymouth bar) protecting it from the ravages of the tidewater Potomac (which it flows into). Here's the spit heading southeast across the mouth of Popes Creek Bay:


This rotted old wooden seawall was erected along the coast in the 1960s. This is on the Potomac, just upstream from the Popes Creek Bay. Effectively, this seawall serves as a "before" line, a marker which conveys the shoreline's former position. You can see how much erosion has taken place since then:


I'm less interested in these coastal dynamics, though, than I am in the bedrock geology. There were some bluffs along the river which exposed the Miocene Calvert Formation (clay-rich lower unit) topped by a foot-thick diamictite unit, and then well-rounded river gravels on top of that:


Here's Merily (sp?) from AGI checking out the sequence of strata:


My favorite part of the trip was looking at the variety of cobbles on the beach. These cobbles are derived from all of the mid-Atlantic's physiographic provinces within the Potomac River's watershed (Valley & Ridge, Blue Ridge, Culpeper Basin, Piedmont, Coastal Plain). All those physiographic provinces have been weathered to produce the sediment that the Coastal Plain is made of. In spite of their diminutive size, they give insights into the geologic history of Virginia over the past billion years. So if you're familiar with Virginia geology, you will see some familiar rocks here.

For instance, there were a lot of these Skolithos-bearing quartzite cobbles. These are pieces of the Antietam Formation, a meta-quartz-sandstone that crops out in the Blue Ridge province, many many miles upstream:


Skolithos is the name given to vertically-oriented cylindrical burrow trace fossils, which start showing up in the Cambrian period of geologic time, indicating the evolution of vascularized bodies among animals. They are usually interpreted as worm burrows. This cobble shows several different diameters of Skolithos tubes:


Here's a cobble of another distinctive Blue Ridge rock. This amygdular meta-basalt is a piece of the Catoctin Formation, a sequence of (mainly) mafic lava flows that erupted as the supercontinent Rodinia was breaking up in the Neoproterozoic era of geologic time. The white spots you see are amygdules: vesicles that have been filled in by mineral deposits. When lava erupts, it degasses. If the lava cools into extrusive igneous rock before the bubbles have a chance to pop, little round holes are preserved in the rock, like Swiss cheese. We call these "vesicles." When vesicles get filled in with deposits of minerals (from groundwater passing through the rock), they are called "amygdules," from the Latin for "almond," which I guess they resemble in an ellipsoidal sort of way:

(I showcased a very similar cobble here in March of this year.) Like the Antietam Formation cobbles, this Catoctin Formation cobble originated in the Blue Ridge province, and has tumbled dozens of miles downstream to end up out here on the Coastal Plain.

Here's one from even further away! This is a cobble of flint from one of the limestone units out in the Shenandoah Valley, the easternmost valley of the Valley & Ridge province. (I've previously posted on those rocks, too.) While the limestone which originally hosted this flint nodule has weathered away, the flint is microcrystalline silica: very hard, very chemically stable. It's a common cobble to find surviving out here in the Coastal Plain:

We also found some rocks that are distinctive occupants of the Culpeper Basin, a Triassic-Jurassic rift valley upstream. Here's a chunk of the Manassas Sandstone Formation, another rock that has been previously mentioned on this blog:


The rock I spend most of my time thinking about is the metagraywacke of the Mather Gorge Formation. (For one mention on NOVA Geoblog, click here.) Here's a piece of it that looks identical to the rocks you'll see near Chain Bridge, DC, or along the Billy Goat Trail (Potomac, Maryland):

This rock was metamorphosed ~460 million years ago, in the late Ordovician, although the original sediments are older than that: perhaps Cambrian or late Neoproterozoic in depositional age. This sample even had a little bit of hydrothermal quartz stuck to it, a common feature of Piedmont metamorphics...

Having covered clasts derived from the Valley and Ridge province, the Blue Ridge province, the Culpeper Basin sub-province, and the Piedmont province, there's nothing left in the Potomac River watershed except for the Coastal Plain itself. And sure enough, we saw Coastal Plain clasts too. Here's a chunk of the Calvert Formation that GSW Field Trip Chair Bill Burton found: He cracked it open and found a shark tooth fossil inside:

This is the first time I've ever seen a tooth preserved as a carbon film. Except it wasn't really just a film, it was more a three-dimensional external mold with a carbon film, and little nuggets of carbonaceous material rattling around inside. Shark's teeth are pretty common in Miocene deposits on the Coastal Plain, including C. megalodon teeth, but this style of preservation was pretty novel for me. If you're into fossil collecting, don't go to George Washington Birthplace National Monument, because collecting isn't allowed there. However, nearby Westmoreland State Park offers legal fossil collecting opportunities. It's about ten minutes further south.

I'd like to thank the field trip leaders and Bill Burton for organizing the trip. I enjoyed the excursion!

Labels: coastal plain, field trips, flint, fossils, gsw, rivers, sediment, virginia

I was reminded this morning to update the list of activities for the coming week, including the Billy Goat Trail hike scheduled for Friday:

Wednesday evening: GSW. Free and open to the public.

Thursday: James Ussher's "birthday of the Earth." How will you be celebrating?

Friday afternoon: I'll be leading a public geology hike along the Billy Goat Trail, starting from the Great Falls Tavern Visitor Center (C&O Canal NHP) at 12:30pm, going til 4:30pm or so. Maybe 5pm. Free and open to the public.

Saturday: GSW Fall Field trip: "Tidewater Geomorphology at George Washington's Birthplace National Monument, Westmoreland County, VA." RSVP.

Labels: coastal plain, field trips, gsw, meetings, piedmont

A reminder to NOVA students, faculty, and interested area geophiles: I'll be giving a talk entitled "Two Months of Rock and Road: A North American geological road trip" today at noon as part of the Science Seminar series. It's in the CE Forum on the Annandale campus. Free and open to the public; light refreshments served.

McCain and Obama having fun: After all the rancor, this makes me happy.

If you're planning on going on the GSW Fall Field trip, let them know ASAP. They need a headcount.

The slate of speakers has been announced for next week's GSW meeting: Leonard Konikow, U.S. Geological Survey, Reston: "Ground-water depletion: National assessment and global implications;" Dionysis Foustoukos, Carnegie Institution of Washington Geophysical Laboratory "Energy sources in dark abyssal waters;" and Igor Puchtel, University of Maryland, College Park "Re-Os isotope systematics and HSE abundances of the 3.5 Ga Schapenburg komatiites, South Africa." 8pm next Wednesday at the Cosmos Club. Free and open to the public; refreshing beverages served starting at 7:30pm.

Virginia's a swing state... unbelievable and amazing.

Radioactive granite countertops cartoon caption contest reminder.

JPL has launched a new climate site:

...And congratulations to Walter Alvarez for being awarded the Vetlesen Prize.

That's all I've got. Have a good Friday!

Labels: field trips, gsw, meetings, news, politics, travel

• "Once I graduated from Graduate school it was tough to really hang out with an entire group of people who like to talk about geology...the geoblogosphere is like a group of friends who like to talk geology...I just wish there was such thing as cyber-beer to go along with the blog-o-sphere ."
• "It's an expanding, welcoming community. You get to experience all sorts of fieldtrips and research through the eyes of other geologists."
• "I have met many professionals in the process of blogging who have given me lots of great help and advice. It has served as a great introduction to specialists I wouldn't otherwise be in touch with."
• "The geoblogosphere connects together a community that otherwise only gets together at a meeting or two per year."

• "It has grown so much and so fast. It is difficult to keep up."
• "Another issue which may arise is priority of ideas. There are now written records of what, in the past, would have been "debates over a beer". Will this lead to debates about who originated an idea, or who has priority on a description?"

As for why geobloggers bother with blogging, the most common response was that they wanted to share information and perspectives with others, followed closely by the sense of connecting with other interested individuals and public outreach. A significant minority also mentioned the pleasure they take in the act of writing, or a desire to practice/improve their writing skills. Some comments from the survey on why geobloggers blog:

• "Narcissism"
• "It's a good outlet for my geological musings, and can really help to jumpstart a day of geo-thinkin'..."
• "An increasingly effective method of public outreach, which is part of my responsibilities as a publicly funded researcher; a way of clarifying my own thoughts on geological topics and issues."
• "Stop mom from emailing me for news all the time"
• "Cogito Ergo Blogo"
• "I like to share what I think is interesting but don't like 'bothering' people. I see blogging as the modern equivalent of the person who tacks magazine/newspaper articles outside their office, but with a much bigger/wider audience."

Labels: blogs, gsw, meetings

Geological Society of Washington
Meeting 1424
Wednesday, September 24, 2008

Sarah Penniston-Dorland, University of Maryland, College Park - "Multiple sulfur isotopes reveal a magmatic origin for the Platreef PGE deposit, Bushveld Complex, South Africa"

Callan Bentley (me!), Northern Virginia Community College - "Rise of the geoblogosphere"

Matthew Jackson, Department of Terrestrial Magnetism (Carnegie Institution) - "The fate of subducted continental crust in the Earth's mantle"

*********************************
Refreshments start at 7:30 p.m. The formal program starts at 8:00 p.m.
Free and open to the public.

Meetings are held at the John Wesley Powell Auditorium (go in via the fenced-in parking lot on the corner of Florida Ave and Massachusetts Ave, NW) of the Cosmos Club, 2170 Florida Avenue NW, Washington, D.C.

GSW Web Site address: http://www.gswweb.org/
Future meetings: Oct. 22, Nov.12, and Dec. 10

Labels: blogs, dc, geology, gsw, meetings

Hi everyone in the geoblogosphere,

I'm scheduled to give a talk in a couple of weeks (at the Geological Society of Washington) entitled "Rise of the Geoblogosphere."

With the talk, I would like to give a comprehensive overview of the geoblogosphere as it stands today, including data about who is blogging, where they're blogging from, when they're blogging, why they're blogging, what they're blogging about, and what they think about this whole blogging deal.

To acquire this information, I've put together a short web-based survey using the "Survey Monkey" service. It's only 10 questions, and shouldn't take more than 5 minutes to do. By participating, you'll be helping create an accurate census of the geoblogosphere's current state, and I will publish the results of the survey here within a couple of weeks.


I will need all responses by Monday, September 15. Please help spread the word by linking to this page (or to the survey itself) from your blog. (Not everyone reads my blog, but maybe they read yours.)

UPDATE (9/11): I've gotten 39 responses as of Thursday morning (only one new addition in 48 hours). There are a more geoblogs out there than 39... If you're a geoblogger, please take the survey sometime this week.

Thanks for participating,

Callan

Labels: blogs, gsw

DC-area residents:

The fall "Walkingtown DC" schedule is now online: see if your schedule permits you to join one of these many excellent walking tours of our fair city. (I'm leading the History Before History one.) Free and open to the public.

NOVA's Alexandria campus is hosting a National Alternative Fuel Vehicle Day event on Saturday, September 20th, from 11am-3pm. The Alexandria campus is at 3001 North Beauregard Street, Alexandria, VA 22311. The flyer I got today on this event says, "Come Speak with Experts and See for Yourself Alternative Fuel & Advanced Technology Vehicles." Free and open to the public.

A reminder that this Friday afternoon, I'll be leading a public geology hike along the Billy Goat Trail, starting from the Great Falls Tavern Visitor Center (C&O Canal NHP) at 12:30pm, going til 4:30pm or so. Maybe 5pm. Free and open to the public.

Also, the first GSW meeting of the academic year is next Wednesday evening...

Labels: action, geology, gsw, oil, prius

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.

Labels: blogs, climate change, CO2, dc, geology, global warming, gsw, nova, piedmont

Last night I attended my first meeting of the Potomac Geophysical Society (PGS). The PGS meets on Thursday nights, and I usually can't make it because I teach on Thursday nights. (I do however attend meetings of the Geological Society of Washington quite regularly, but those are on Wednesday nights.) Now that the semester is over, I was able to make it to the final PGS meeting of the spring.

The meeting was held at Fort Meyer Officer's Club. It's on a military base adjacent to Arlington National Cemetery, and before entering, my Prius had to be searched for bombs (as did all other civilian vehicles). The Officer's Club was about what you would expect, I guess -- kind of 1950's decor, elegant once. I noticed they had compact fluorescent light bulbs in all the sockets, which pleased me. PGS meetings consist of: (1) beer downstairs in the lounge, (2) dinner upstairs in the "Campaign Room," (3) business details, and (4) a talk by a guest speaker.

Last night's speaker was Bill Burton, from the USGS's volcano hazards and monitoring program. Bill's office will be launching a comprehensive new volcano website later this year, and he gave us a brief preview of its features in last night's talk. If you'd like a look for yourself, they have a beta version of the site online now.

Labels: gsw, meetings, pgs, volcano, websites

On Thursday, I posted some reflections on one of the talks at the most recent meeting of the Geological Society of Washington. At the same meeting, there was another talk that got my attention, and I wanted to briefly share its findings with the geoblogosphere. The talk was entitled "Mineralogy of the Atmosphere: Assessing environmental and health impacts of airborne particulate matter." It was given by Reto Giere, of the University of Freiburg, Germany. (He's currently in DC as a Visiting Investigator at the Geophysical Laboratory of the Carnegie Institution of Washington.)

Reto's research has lately focused on particulate matter in the air. He collects it and then evaluates it using transmission electron microscopy, X-ray diffraction, and other techniques. The first point he made in Wednesday's talk is that "soot" is a matter of definition. Natural and anthropogenic sources can both be found in the sub-1-micrometer range. If you look at small particulates, Switzerland's environmentally-lauded train system actually generates three times as much "soot" as their traffic output.

So what's in that "soot?" Turns out that a lot of it is anglesite, PbSO4 and some of it is gunningite, ZnSO4'H2O. (There are also droplets of elemental selenium, Se.) The majority of these metal sulfates (and others) are coming from flue gases from power plants. And the thing is, because they're so small, all these goodies end up in our lungs. Reto has run modeling experiments to see what weight-percent of the average person's dose of inhaled metals gets extracted by the lung fluid. In one week, 80% of the zinc was absorbed by the lungs, 55% of the nickel, and 35% of copper. Yum! (I would have been interested to see the actual masses of these absorbed metals compared to the quantities present in a typical vitamin pill, but that wasn't covered.)

There's good news that stems from Reto's work too: the particular "cocktail" of minerals in a sample may be diagnostic of a specific source, which would be useful for forensic identification of polluters. Overall, I found it an interesting talk, on something I'd never really thought about before.

Labels: environmental, gsw, minerals

Last night at the meeting of the Geological Society of Washington, we were treated to a couple of really entertaining talks. The first was by John Eichelberger, of the U.S. Geological Survey in Reston (formerly of UAF). John is interested in Plinian eruptions -- the ones where volcanoes shoot massive amounts of ash and gas upwards in an eruption column. He made the point that while Plinian eruptions are widely characterized as "explosive," they are actually a steady state phenomenon with a high volume, "like a firehose."

Labels: gsw, volcano

Last night at the year's first meeting of the Geological Society of Washington, Derek Schutt of the National Science Foundation gave a talk entitled "The Yellowstone hotspot and how it got that way." Derek mainly focused on the evidence for there indeed being a mantle plume under Yellowstone, possibly caused by the destabilization of the core-mantle boundary layer when subducted Farallon lithosphere sank down to the bottom of the mantle.

But the thing that he said that really caught my attention has to do with one of the weird aspects of Yellowstone. Yes, to the southwest of Yellowstone's modern caldera is the Snake River Plain, a series of ancient calderas which overlap one another, getting older and older the further to the southwest you travel, until you get to the oldest one at 17 Ma. That part of it looks pretty much like a classic hotspot track, a la Hawaii. But there's a weird aspect to Yellowstone that doesn't fit the traditional hotspot stereotype: starting at that same 17 Ma caldera/"rift," another series of eruptions propagated away to the west/northwest, including the voluminous Columbia River flood basalts and leading to the Newberry Caldera, which Derek described as "the largest basalt dome in the United States." (See the map above, from Schutt's collaborators Gene Humphreys and John Hernlund.)

So, the question is: What's up with that? It kind of looks like two hotspots heading in different directions. Is this linked to the stretching of the western U.S. via the Basin and Range? Derek pitched another idea, which is based on the thickness of the lithosphere (crust + uppermost mantle). His idea is summarized in the diagram below, which I drew this morning based on my rough sketch of the diagram he put up on the screen at GSW last night. (My apologies to Derek if I've gotten any of the details wrong.)

The basic idea is that the North American lithosphere is thicker to the east, under Yellowstone, which Derek (admittedly loosely) defined as the Wyoming Craton. He suggested that the lithosphere was thinner to the west under Newberry and the Columbia River Plateau, since those were accreted terranes added to North America during the Mesozoic. The mantle plume came up underneath the thicker lithosphere, and punched a hole through right above it (Yellowstone), but part of the plume slid upwards and westwards towards the thinner lithosphere, where it broke through in multiple locations, producing first the Columbia River flood basalts and then later the eruptions culminating in Newberry. I like the idea, and the picture Derek showed is elegant. I can picture this happening, if the suggested lithosphere thicknesses are true. The question is, are they? I don't know enough about that region of the country (yet) to assess the validity of this model. I wanted to use this blog post to share the notion, and see what people think. If you're familiar with that area, please clue me in to the details.

An additional difference between Yellowstone and Columbia River/Newberry (CR/N) is that Yellowstone's magma is rhyolitic and CR/N's magma is basaltic. Rhyolitic magma is a lot more explosive than basalt, and indeed Yellowstone's eruptions have been among the most powerful observed in the geologic record. (The Huckleberry Ridge tuff, which erupted from Yellowstone 2.1 Ma, is deposited over something like half of the Lower 48!) CR/N, on the other hand, appear to be gentler eruptions more like Hawaii's oozing of basalt. I suppose this too can be explained by Derek's model: partial melting of the more-felsic crust under Yellowstone (as hot plume magma heats that thicker slab of continental crust), but a shallower Moho to the west, producing mafic magma a shorter vertical distance from the surface.

PS -I must also add that it was great to meet Tuff Cookie of Magma Cum Laude at the meeting. If there had been one more of us there, it could almost have been a geology blogger's conference.

Labels: gsw, yellowstone