Wednesday, February 25, 2009

...and then two more.

I was tempted, in light of specific sentences said by a particular politician yesterday, to forgo my planned Accretionary Wedge post and instead write about how every geologist, at some point in his or her life, should engage in a little volcano monitoring. I totally stand by my statement (and will be taking a class next quarter that absolutely involves volcano monitoring), but I also recall that we're collectively trying to come with 100 things, and there is certainly enough room in the budget of geological curiosity/exploration for me to write about those things in addition to snarking about things that other members of the geoblogosphere have already addressed so eloquently.

And now, the post I was planning to write before this madness went down.

The original 100 Places Meme lists the San Andreas Fault as a Must-See. I absolutely agree with this, but as I was marking the text on the list in bold, I got to thinking about how those three words mean a whole slew of very different places, spread out over hundreds of miles. The ultimate San Andreas experience is, of course, to drive the whole thing (or, well, the parts that are on land). I can't check off the full 800 miles yet, but I've been from the southern end of the Fault at the Salton Sea up through Point Reyes, mostly on roads that cling pretty close to the surface trace. I definitely recommend this drive as a means to check off the San Andreas on the original meme, but I also feel like there are several specific must-see sites along its trace (and within its system of associate faults) that deserve space on the expanded list.

The first place that came to mind, without me even having to really think about it, is Carrizo Plain National Monument, in rural San Luis Obispo County. The quintessential image of the San Andreas, the one that pops up in all sorts of textbooks and popular science books about earthquakes, the first photo that turns up when one does a google image search for the San Andreas, is from the Carrizo. It's an aerial photo of the Elkhorn Scarp, also known as the Dragon's Backbone, a 17-mile-long pressure ridge that, from above, looks like a gaping chasm into the depths of the Earth. (The original Superman movie actually does use the scarp as Supes' entry point into the fault...) It is a spectacular photo, but the view from the ground is equally breathtaking, and has the added bonus of debunking the faults-as-gaping-chasms myth.
The Carrizo Plain is one of the best places to see a wide variety of features associated with continental strike-slip faults. In addition to the outstanding pressure ridge, there is the famous Wallace Creek. This streambed crosses the San Andreas, but not without getting pulled around a bit first. Wallace Creek takes a sharp right angle turn as it meets the Fault, then parallels it for some 130 feet before heading back on its course. This shows the displacement power that the San Andreas has, and is all the more staggering when taking into account that some people think a good percentage of that displacement came from the 1857 earthquake alone. There are plenty of other offset streambeds that are less dramatic, as well as some channels that have been "beheaded" by the fault. The Carrizo also boasts more typical scarps, some spots of more trenchlike fault expression, stepovers with traceable surface expression, and a few (mostly dry) sag ponds.

If faults aren't really your thing, the Carrizo Plain is still worth a visit. The northernmost part of the Plain contains Soda Lake, a huge alkaline lake out of which many spectacular mineral samples (some of which are in the Visitor's Center, which is not open all the time) have been extracted from not very deep. The Carrizo is also thought to be an example of what the native Californian landscape might have looked like before the Europeans did anything to it - fields dominated by wildflowers and scrubby plants. For this reason, late March and early April are the best time to visit, since the wildflowers are out in full force, and the entire Plain is painted in shades of green, yellow, orange, and blue. (Don't go in the middle of the summer, though, unless you like triple digit temperatures.)

The next place I want to add to the list doesn't strictly feature the San Andreas; the town of Hollister's bisector is the Calaveras Fault, though the Calaveras branches off from the San Andreas just south of the town. The seat of San Benito County may lack scenes of breathtaking beauty that could make even a non-geologist drool, but it's also one of the best places to see the bizarre California-centric phenomenon known as aseismic creep. Creep is a phenomenon in which a fault moves slowly and steadily at around the tectonic loading rate, constantly releasing stress in a way that does not radiate seismic waves and generally prohibits enough buildup to cause a large quake (though some creeping faults may have asperities within the creeping zone that still accumulate stress and rupture seismically, even though creep continues around that zone). The main place (if not the only - I haven't heard of it elsewhere) this has been observed is in California, specifically on the Hayward, Calaveras, and Rogers Creek Faults in the Bay Area, the San Andreas between Parkfield and San Juan Bautista, and the Superstition Hills Fault near the Mexican border.
Creep can be measured with all sorts of complex instrumentation, but its easiest for the layperson to see when some sort of manmade structure gets put on the fault, and proceeds to get bent and deflected and cracked. The cities of Santa Rosa, Berkeley, Hayward, Fremont, and others all have the trademark offset curbs of a creeping fault, but I personally think that Hollister is the best city to look for offset because it looks like they've put less effort (or money) into patching up the distortion. Some sidewalks are bent several feet out of line, many streets are crossed by sets of en echelon cracks, and some houses and garages have obvious bulges in the walls and cracks in the foundation.

So Hollister is a good place to see creep as a phenomenon in and of itself, but it's also a clear exhibition of the interaction between the Earth itself and its inhabitants, of how people keep living in some places in spite of the geology. I suspect the fault was not known to be there when Hollister was first founded, which could explain some of the spectacularly bad locations of houses, but towns like this can be an example of how the hazards of the landscape should be taken into account when planning future development.
Not to mention that such intersections of humanity and seismicity make it clear that Fault Monitoring is also pretty darn important...

Monday, February 23, 2009

100 things...

So, since the upcoming Accretionary Wedge is about our personal addenda and recommendations for the Geologists' Life List, I figured I should do the actual original meme before writing up my entry. No matter how late on that bandwagon I may be...

The ones I've done/seen are in bold. Comments are in italic.

1. See an erupting volcano Not yet, but it seems very possible for April or May!
2. See a glacier
3. See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland
4. Visit the Cretaceous/Tertiary (KT) Boundary. Possible locations include Gubbio, Italy, Stevns Klint, Denmark, the Red Deer River Valley near Drumheller, Alberta.
5. Observe (from a safe distance) a river whose discharge is above bankful stage
6. Explore a limestone cave. Try Carlsbad Caverns in New Mexico, Lehman Caves in Great Basin National Park, or the caves of Kentucky or TAG (Tennessee, Alabama, and Georgia) How about Luray Caverns, in Virginia?
7. Tour an open pit mine, such as those in Butte, Montana, Bingham Canyon, Utah, Summitville, Colorado, Globe or Morenci, Arizona, or Chuquicamata, Chile.
8. Explore a subsurface mine.
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus (if on a budget, try the Coast Ranges or Klamath Mountains of California). There is no excuse for why I haven't seen one of these yet.
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).
11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. They reside on the Colorado Plateau. Among the best are Antelope Canyon, Brimstone Canyon, Spooky Gulch and the Round Valley Draw.
12. Varves, whether you see the type section in Sweden or examples elsewhere.
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland.
15. Coastlines along the leading and trailing edge of a tectonic plate.
16. A gingko tree, which is the lone survivor of an ancient group of softwoods that covered much of the Northern Hemisphere in the Mesozoic.
17. Living and fossilized stromatolites (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones)
18. A field of glacial erratics
19. A caldera
20. A sand dune more than 200 feet high
21. A fjord
22. A recently formed fault scarp How recent is recent? I've seen one from 1971...Failed miserably at finding the Landers scarp, though.
23. A megabreccia
24. An actively accreting river delta
25. A natural bridge
26. A large sinkhole Apparently there is a sinkhole in the middle of the 215 freeway right now...
27. A glacial outwash plain
28. A sea stack
29. A house-sized glacial erratic
30. An underground lake or river
31. The continental divide
32. Fluorescent and phosphorescent minerals
33. Petrified trees
34. Lava tubes Another thing I will probably get to see in April or May!
35. The Grand Canyon. All the way down. And back. Saw it out the window of an airplane...
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m)
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale.
40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.
41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing
45. The Alps. In Germany, Austria, and Italy. Though I went there for music-related reasons...
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below. There's also no excuse for why I haven't been to Death Valley yet, but that will probably be fixed this year.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art
48. The Dalmation Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. Shiprock, New Mexico, to see a large volcanic neck
52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity
61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault This could mean so many very different places!
70. The dinosaur footprints in La Rioja, Spain
71. The volcanic landscapes of the Canary Islands
72. The Pyrennees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress)
75. A catastrophic mass wasting event Does the Blackhawk Landslide in the Mojave count? Or does the question imply having actually witnessed the sliding?
76. The giant crossbeds visible at Zion National Park
77. The black sand beaches in Hawaii (or the green sand-olivine beaches) Again, might happen in April or May!
78. Barton Springs in Texas
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado
81. The Tunguska Impact site in Siberia
82. Feel an earthquake with a magnitude greater than 5.0. The M5.4 Chino Hills quake on 29 July 2008
83. Find dinosaur footprints in situ
84. Find a trilobite (or a dinosaur bone or any other fossil) I have olenellid trilobite heads from the Marble Mountains, Mojave Desert.
85. Find gold, however small the flake
86. Find a meteorite fragment
87. Experience a volcanic ashfall
88. Experience a sandstorm
89. See a tsunami
90. Witness a total solar eclipse
91. Witness a tornado firsthand. Part of me really wants to. Another part of me would probably collapse into a quivering ball of terrified.
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower
93. View Saturn and its moons through a respectable telescope. Also, Jupiter.
94. See the Aurora borealis, otherwise known as the northern lights.
95. View a great naked-eye comet, an opportunity which occurs only a few times per century Hyakutake in 1996 and Hale-Bopp in 1997.
96. See a lunar eclipse
97. View a distant galaxy through a large telescope
98. Experience a hurricane Does a tropical storm count? Been in several of those, but none were actually hurricanes when they got to where I was. Going out on the beach during a tropical storm is not really pleasant, even if it's interesting - getting pelted with sand at 60mph hurts!
99. See noctilucent clouds
100. See the green flash

That is not exactly the greatest showing ever. But I must remind myself that I've only been involved in geology in a non-popular-science-books-and-documentaries way for less than two years. I guess that's not so bad?

Saturday, February 21, 2009

Geology: Bringing Families Together

My younger brother is not much of a phone person. He actually isn't much of a continuous conversationalist in general, due to a combination of autism and a wide array of interests. In person, this makes him the King Of The Non-Sequitur, and a single conversation could contain traces of politics, football, recaps of favorite TV shows, NASCAR, video games, and whoever he's decided he thinks is hot. Sometimes these may all happen in a single paragraph.

He's just never really gotten the hang of the phone, though. A typical conversation with him consists of, "Hi, how are you?" And I'll respond, and he'll go, "Ok, bye!" He usually has to be prodded to talk to someone to begin with.

But this week, when I was on the phone with my parents, he specifically asked to talk to me. The reason for this? He's enrolled in Callan's intro geology course at Northern Virginia Community College, and clearly knew this would be something I'd be glad to discuss with him. (I think he's finally catching on that I don't care about NASCAR in the slightest.) To my utmost surprise, he talked with me about the topic of igneous rocks for fifteen minutes straight, with no changes of subject or express of unease about the phone itself. Fifteen whole minutes!

I was, of course, thrilled that he expressed such enthusiasm about the subject matter (and Callan, I'm sure you'll want to know that he got almost everything right when I quizzed him on things), but I think I was even more excited about the evolution of his conversation skills. It was really wonderful to talk with him for that long, especially since I only get to see him twice a year. Even though he didn't tell me directly how he's doing - he never does - I can tell he's getting along well and happily, based just on how vivid and prolonged that conversation on rocks was.

(And because I am so happy, I am going to embarrass him on the internet! Hah! Sibling duty! Even though I'm absolutely certain he doesn't read blogs. Love ya, M!)

Saturday, February 14, 2009

Volcanic Hazards for Humanities Majors

I have emerged from the depths of mid-quarter reading onto the island of Three-Day Weekend to make a post to my blog!

I taught my very first geology lecture on Tuesday. While I'm not technically a TA this quarter, I will be next quarter, and this lecture was for the same class. I ended up teaching this week because my adviser was out of town giving talks, and needed someone to cover for him. The class in question is one of those massive nonmajor earth science requirement courses - Natural Hazards. (Or, Ways The Earth Can Kill You, For Non-Majors.) This is normally a huge 500-person course, but the section this quarter is part of a special year-long course on California in general (first quarter was an English class on California novels, third quarter is on Native American history), geared at humanities majors in particular, and there are only 75 of them in the class. A slightly less formidable audience for a first big lecture!

This was not the first time I've ever taught; I was a TA for a year in the music department, but that was a much smaller class. My discussion sections had five students each, and they were supposed to sing for me. I have already found that it's much easier to impart information on a topic to a group of people than to make them practice a practical skill that they really really don't feel like doing. (It's especially hard when some of them can't even tell that the note they're singing isn't even in the same ballpark as the note I'm playing for them.)

Anyway, the lecture I got to give was about subduction zone and continental caldera volcanoes. This was very exciting to me, because volcanoes were my first geologic love, at age five or six. When you're that little, books about volcanoes tend to also be about earthquakes, so I quickly developed an interest in those as well, but the volcanoes did come first. My adviser's previous lecture had been about Hawaii and Iceland, so I got to jump right in with the really big booms. It necessarily had to be a pretty simple lecture in terms of explanatory science (the textbook states everything in terms of The Three Vs Of Volcanism: Volume, Volatiles, and Viscosity); I was supposed to cover the phenomenology of big bad eruptions more than anything else. I spent a good long time on pyroclastic flows and lahars, with historical examples from all over the world, then went into more depth on sequence of a stratovolcano eruption by describing (of course) Mt. St. Helens. (I also mentioned that Mt. Redoubt is a stratovolcano with imminent eruption, though not on that sort of scale, and I was surprised that nobody seemed to have heard of it!) I ended by tying these rest-of-the-world examples in with specific California sites (ski Mammoth before it blows, guys!), and by showing video of the Salton Sea Mud Volcanoes, because they're awesome.

I really tried to impart the impression that, "These volcanoes are fascinating, beautiful, and can totally kill you," and I really hope that more than just the two talkative students came out of the lecture sharing my enthusiasm and trepidation over all things volcanic. As I expected, based on the undergrad level classes I've taken here, the class was pretty quiet and stonefaced throughout, and they seemed loath to actually answer the questions I asked, even though it was stuff they totally should have known from the previous Thursday's lecture, if nothing else. I hope that their lack of response was just because I was the new unfamiliar guy, and have no actual grade-giving power. Because seriously, how could anyone not find extremely explosive volcanoes even a little bit cool?

Despite the unresponsiveness, I enjoyed giving this lecture, and it was definitely valuable practice for future TAing and lecturing in years to come. I'm looking forward to properly TAing this class next quarter, even though I know to expect some degree of apathy from people who are mostly just filling gen-ed requirements. I'm hoping I'll be able to indoctrinate at least a few of them into enthusiastic geogeekery!