Tuesday, November 30, 2010

The Upsides and Downsides of Mountains

I’ve lived in Western Washington for a total of twenty-one years, so it’s really easy for me to answer this month’s Accretionary Wedge (#29!) as posed by Ann at Ann's Musings on Geology & Other Things: "What Geological features about the area you call 'home' do you love? and what do you not like?"

Washington can be divided very roughly into thirds: Eastern Washington, home to the Missoula Flood-carved Columbia River Flood Basalts; Western Washington, with thick glacial deposits and steep stratovolcanoes in the Cascade Mountains; and the Olympic Penninsula, which is an accretionary wedge, with the uplifted Olympic Mountains.

My favorite geological features are the volcanoes. These result from the subduction of the Juan de Fuca plate beneath the North American plate:
Map, Plate Tectonics and the Cascade Range, [18K,GIF]

Cascades Volcano Observatory

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Mt. Rainier

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Mt. St. Helens

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Mt. Adams

 

Now, my least favorite geological features of Western Washington are also the Cascades, because they help cause the massive, constant amounts of rain.

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The Olympics create a rain shadow, but they aren’t so high that all the moisture condenses and falls: the rest is carried over the Puget Sound. As it does so, it picks up more moisture, which then condenses as it rises over the Cascades, dropping all over Western Washington.

That’s why it rains 365 days out of the year (or at least feels like it!)

Thus, my Theory of Seattle: the rain nourishes the trees and shrubbery, which grows profusely and blocks out the light. Between the rain and the trees, everyone wants to stay indoors – thus, the major IT industry begins. Between the masses of commuters and the nasty dim weather, rush hour runs rampant. Since everyone codes late into the night and has to get up early to beat the traffic, the immense coffee culture is started. Thus, the population has a Vitamin D deficiency, stares at computers constantly, is always struck in traffic, and gets regularly strung out on coffee, resulting in perpetual depression and tweakiness. Thus leading to the reign of 90s grunge music, which also contributes to the high suicide rate.

That’s my theory, at least. And I’m sticking to it.

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I’ll be honest: I’ve had my fill of the dreary rain and endless rush hour.

So, I’m going to study Geology at Boise State University next year!

Thursday, November 18, 2010

Boil, Boil, Toil and Trouble: Lava Cave Features

 

Lava tubes frequently show fantastic features, and I saw some really cool features while I was interning through the GeoCorps Program with the BLM at Craters of the Moon National Monument and Preserve. Some of the more decorative formations are the result of boiling gases inside the lava. Honestly, I hadn’t seen many of these formations before this internship, so it was very exciting!

It was interesting to learn more about lava: how the tube walls themselves cool, how secondary flows erode the original tube, how both cohesiveness and fluidity contribute to form features, and how the pressure in the flow creates different landscapes (like pressure ridges and tumuli.) Being able to observe a great quantity of lava over the course of three months was highly educational - even if I can’t cite lava facts of statistics, I know more about the characteristics of lava by seeing so much of it.

I know I haven’t given much information on the region’s geology itself, but that’s because I get too darned excited about lava tubes.

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As the ceiling of a lava tube is cooling: first the exterior layers, and then the interior. Once the exterior layer has begun congealing, gases in the interior lava can boil, squeezing lava out through the exterior layers. (Kind of like a pasta machine.) As this lava drips down, the sides of the drip cool, leaving the liquid lava inside. This liquid lava can then flow to the bottom of the stalactite, creating a hollow space. Sometimes the last bit of the drip falls off the stalactite, other times it plugs the stalactite up. The left picture shows some stubby stalactites from Craters of the Moon, and the right picture shows some really delicate “soda straw” stalactites from near Mt. St. Helens.

If the lava inside these stalactites drips onto the ground, it can pile up to form a stalagmite. I didn’t see many in Idaho, but the ones I did see were really tall. Unfortunately, I didn’t have a camera that day, but I also saw some good ones in Bend this summer.

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These are called “stalagpies” by the local cavers, but are more widely known as lava roses, especially when they have a clearly defined series of concentric rings. I think they look a bit gross, but they can form in a really nifty fashion: when lava boils from under a semi-cooled floor, the pressure of the gases pushes the lava up through the floor. As a result, these are also sometimes called “lava volcanoes.” These are identifiably by their “central conduit,” which can be easily seen in the bottom picture. These pictures are from a lava lake, so this explanation makes sense.

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Because these don’t have a conduit, I think this is an example of the other way in which lava roses form: when larger clumps or sheets fall from the ceiling, and pile up, cooling, slumping, and cracking as they do so. (I think the right one is especially ugly – it resembles a miniature Horta.) These pictures are from a different cave than the previous lava roses – so a different origin is plausible.

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These are lava helictites! These are created in a manner similar to the lava stalactites above, but the lava is pushed through weak spots in the developing crystal structure, forcing it into a twisted shape. Both lava and calcite helictites refuse to obey gravity.


References:

If you want to learn more about lava caves and their features, here are some great resources:

The Virtual Lava Tube is an easily accessible resource, complete with beautiful pictures. This site is run by Dave Bunnell, editor of the National Speleological Society News. He also published the information in a book called Caves of Fire: Inside America's Lava Tubes, which is gorgeous.

Nomenclature of Lava Tube Features is an older article, but describes a greater number of features than the Virtual Lava Tube, including many different types of stalactites and pahoehoe lavas. It’s available in print form in the proceedings of the 6th International Symposium on Vulcanospeleology, and in illustrated form as An Illustrated Glossary of Lava Tube Features. (I wish I’d found the online copy earlier – I accidentally left my print copy in storage!)


An aside: nothing I say on this blog represents the opinion of Craters of the Moon National Monument and Preserve, the BLM, the NPS, the Geological Society of America, GeoCorps, or the National Speleological Society and its internal organizations. I will not disclose any cave locations, but if you wish to go caving in Idaho, please visit Craters of the Moon National Monument (NPS,) the Shoshone Field Office (BLM),  or get in touch with your local caving club.

Sunday, November 14, 2010

The People of Armero, 25 Years Later

It’s been 25 years since Nevado del Ruiz erupted on November 13, 1985. Despite being a relatively small eruption (VEI 3), this phreatic (magma + water) created a massive lahar (mudslide) and managed to wipe out an entire town, killing 23,000 people in the process. Good descriptions of the eruption can be found on History of Geology and Eruptions, so I’m not going to reinvent that wheel.
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From the USGS
Last spring, I researched Armero in the present day for a cultural project in Spanish class. The assignment was to communicate with a native Spanish speaker in Spanish, so I sent a (painstakingly composed) email to  Observatorio Vulcanológico y Sismológico de Manizales, one of the volcano observatories set up after the 1985 tragedy.
Now, it has been 25 years since Nevado del Ruiz erupted, and, in the aftermath of eruptions, frequently people return to the destroyed area. There could be a variety of reasons for this – they don’t think it’s likely to erupt again, they have nowhere else to go, for religious reasons, or they simply want to be “home.” A great example of this is Merapi, in Indonesia, which seems to erupt roughly every ten years, and its lahar deposits re-liquify into new lahars every monsoon season. That people still live nearby to be affected by the current eruption is a horrific testament to misplaced perseverance, determination, and religious conviction. After the 2002 eruption of Mt. Nyiragongo, in Congo, people moved back to the destroyed town of Goma before the lava had even finished cooling. However, habitation in an area previously destroyed by recorded natural disasters isn’t relegated to what we would consider “third-world” countries: people still live in New Orleans and near Mt. St. Helens, astonishingly enough. As time passes after an eruption, people are increasingly more willing to return to these areas – the valleys surrounding Mt. Rainier are filled chock-a-block with farms, industrial complexes, and towns.
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From here
In light of that, my curiosity about Armero was regarding where in that process the government and people were – had they begun to forget, or did the scale of the tragedy make it more difficult to ignore the hazard? Had I known more vocabulary, I might have asked more specific questions, but the ones I managed to include were thus: what is the town of Armero like today? How many people have returned to live there, and how do they perceive Nevado del Ruiz?
I got a fantastic response back from the volcano observatory, which, after some I looked up several words, answered most of my questions. The representative explained how the old site of Armero had been declared a National Cemetery, and habitation was no longer permitted there. Now, the survivors and municipal administrators had moved to the town of Guayabal, now called Guayabal-Armero. Apparently the area has become a destination for over 35,000 tourists a year, and there are volunteers available to provide tourist guidance.
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From the USGS
That led to some more focused googling, with the result that I found out about the Fundacion Armando Armero, an organization devoted to preserving the cultural heritage of Armero. They’ve set up an interpretive site in the old town, focusing on people and places found in Armero before the eruption. In addition, they are working on building a cultural-tourism route through Guayabal-Armero and Armero. One of their other projects includes collecting photos and stories of old life in Armero, some of which are available on their website.
From Wikipedia
It was interesting to learn a little more about how this area is recovering from such a devastating incident. It sounds like the government has more respect for volcanoes, that the people are coping, and the efforts of the Fundacion Armando Armero are laudable. Still, I wonder whether the cooperation of the people will last, or whether they will someday decide to reclaim their town.

Other Resources:
Observatorio Vulcanológico y Sismológico de Manizales
 USGS: Nevado del Ruiz
Global Volcanism Program: Nevado del Ruiz
No Apparent Danger, Victoria Bruce, HarperCollins Publishers, 1st Ed., 2001

Wednesday, November 3, 2010

A Couple Nice Eastern Washington Pictures

A few weeks ago, I spent a weekend near Prosser, WA with my parents and their friends. This was their annual bicycle-riding and wine-tasting weekend, so most of my pictures feature middle-aged folks in spandex. Much as I’ve become desensitized to such retinal injury, it seems rude to inflict it upon the internet. I did take some decent travel photos, however:

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The last one shows some hop trellises. Washington state produces much of the world’s hops, believe it or not.