geology | Yellowstone Treasures

Oct

Yellowstone Rock Analysis 101

Categories: Science

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Not long ago I received a picture of a rock that came from Yellowstone, sent to me by e-mail by a visitor who had picked it up this summer. So I asked my geologist husband to take a look at the picture. Every geologist gets asked frequently to help a friend or acquaintance figure out what some rock is. As you can see from what I wrote to this correspondent, it isn’t all that easy!

. . . I’ve consulted my geologist husband about your rock, and he and I came up with some ideas to pass on to you, but we cannot really answer your question.
I have to say I am very sorry you picked up this rock, since it really is against the law in all national parks to take anything natural out of the park. [Ed.: She later found out that they did not remove the rock from the park.] “Take only pictures, leave only footprints” applies to everyone. However, since you did take it, I’ll send a few comments.
1. If you can remember where you were when you picked up the rock, that would help a geologist determine what it is, since the entire park has been mapped for its geologic history.
2. Are you sure it’s a rock and not something manmade that is highly weathered? It is probably a rock if it’s heavy and dense. Note that a weathered surface may look entirely different from an unweathered one.
3. Were there a lot of rocks that looked like this lying about or only one or two? This would be a clue as to whether it was part of the bedrock of that area or brought there by a glacier or former stream.
4. To properly analyze a rock you have to break it open with something like a sledge hammer against a hard surface and separate rock fragments from anything else.
5. When broken, does the inside look the same as the outside, especially the color? Do the dark bands go through the entire rock?
6. Related to where you picked it up, it may be either a sedimentary rock (probably laid down in layers at the bottom of a sea or lake) or, more likely in Yellowstone, an igneous rock containing magnesium and iron that’s left from a long-ago volcanic eruption.
7. A far-out guess might be that the whitish parts might be plagioclase (igneous feldspar) and the greenish parts, pyroxene or olivine.
The main thing is that a geologist really must both know where it came from and be able to see and physically test it to determine what it is.
2012

Oct

Reviews and Constructive Criticism, Part 2

Categories: On the Web

Tags: geology, guidebooks, reviews

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One long review with a useful criticism

Recently I decided to go through the ideas of one reviewer carefully for constructive suggestions—and I found one! More about what I learned and about what I can’t resist disagreeing with will appear soon in a new nugget of information on our website. [See The Features of Yellowstone Treasures.]

One thing the reviewer certainly got right: the book certainly reflects the author’s interests—and what book does not? I check out as many places in Yellowstone as I can every year, but I confess that I spend the most time where I most like to be.

I thank the reviewer for saying he “got a sort of ‘wikipedia’ to Yellowstone” instead of what he was expecting. That’s a compliment!

Aug

Counting the days

Categories: Bio, Trip Reports

Tags: geology, guidebooks

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I am counting the days until I leave for Yellowstone country. Ten days from now I’ll get close, but I’ll start south of the park to do some research in a library collection in Provo, Utah, and then visit old friends in Jackson Hole.

Then the real work begins. I have lots of things to check out in the park for Yellowstone Treasures. I suppose no guidebook can ever be declared finished, since it is only valuable if kept up to date with the changes that inevitably occur. Yellowstone is more prone to changes than most areas, what with all those geysers that keep changing their personalities. And parts of the roads may be different from a few years ago, along with other man-made features. Then, too, there are always ways to improve a book in general.

For the next edition I want to bring the writing about the geology of the park up to date. Yes, you would think the rocks would stay the same, but geology isn’t just about rocks, it’s also about how the earth got the way it is, how the geology affects all the living things in the neighborhood, and what may be going on under our feet that will bring about changes. Several types of geoscientists are working continuously to better understand the processes that make Yellowstone so marvelous.

Then, too, I’m always trying to understand what geologists are learning and bring some of it to my readers. Helping me this year is an old friend and PhD (from Brown University) in geology, Jo-Ann Sherwin. My map maker, Linton Brown, is back at work tweaking the maps, sometimes in subtle ways, and my editor and my book designer, daughter Beth Chapple and friend Alice Merrill, are doing their things for better verbal expression and design. With a little luck, we’ll have some new pictures to share, too.

And, of course, the Internet and phone access are both a bit iffy where I’m going, so I won’t try to write blog posts while there. There will be more words from me on this blog before I leave home, though. . . .

[August 2012]

Jun

Yellowstone Volcano Observatory scientist not worried about an imminent supereruption

Categories: Science, Thermal features

Tags: eruptions, geology

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Today I’m wearing my Supervolcano T-shirt, acquired at a preview showing of the 2005 BBC/Discovery Channel movie of that name. It was a scary movie for anybody, and the Internet spin it engendered has continued, since apparently many people have taken this fictional treatment as something all of North America needs to worry about from now on. Yellowstone Treasures (meaning me) interviewed our geologist (my husband Bruno) about this, and we put his comments up on our Web site soon after the movie was shown. See the nugget called “The Yellowstone Supervolcano.”

Even before that movie came out, the USGS had set up the Yellowstone Volcano Observatory, and Jacob Lowenstern is now its esteemed head scientist. Here’s part of what he said in a recent e-mail interview. Before upping the Yellowstone supereruption alert level, he wrote, “we’d need to see more going on than what we’ve seen, and we’d want to see deformation and earthquakes happening simultaneously and in some abundance.” Even those warning signs wouldn’t necessarily mean a massive eruption, the scientists are quick to note. “Scientists are reasonably good at short-term forecasts of volcanic activity but cannot look long into the future.” However, Earth’s tectonic plates are too complex for their future to be knowable. Thus, in lieu of predicting exactly when specific earthquakes and volcanic eruptions will happen, geologists “typically rely on probabilistic evaluations that are based on how often volcanoes have erupted in the past.”

“At Yellowstone,” he continued, “activity is clearly episodic. There was a very long period of volcanic activity between 170,000 years ago until about 70,000 years ago. Many tens of lava flows erupted during that time, though none were nearly as explosive as the supereruptions that are so oft-discussed in the press. Since 70,000 years ago, there have been no volcanic eruptions at Yellowstone. Nearly all geologists I know expect that Yellowstone will experience future volcanic eruptions, but we honestly cannot state when they will occur, nor do we know if there are any more supereruptions in Yellowstone’s future.

“It could still be tens of thousands of years before the next eruption. Having said that, it is always possible that things could change… and that’s why we keep a close watch.”

I’ll be wearing my Supervolcano T-shirt in the park, starting June 20th [2011]. . .

Aug

Supervolcano: are we ready for another caldera explosion?

Categories: Science, Thermal features

Tags: eruptions, geologists, geology

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[Update 6 Sept. 2010: Looking at this post’s title again, I realize the word “ready” is ambiguous there. We will never be ready to be inundated with hundreds or thousands of square miles of ash and lava. The hope is simply that we can be warned in time to get out of the way when it does happen. And that is the best that modern scientists can prepare us for at this time. Such forces of nature do not wait for man to figure them out.]

As I pack for my annual trip to Yellowstone, people ask me if I worry about the escaped Arizona criminals being in the area or the potential eruption of the so-called supervolcano. My answer is no to both, since the chance of running into the criminals is probably less than that of being struck by lightning, and the caldera eruption will give us ample warning, now that the equipment and organization of the Yellowstone Volcano Observatory team is in place.

Predicted in our interview with Yellowstone Treasures’s geologist is the putting in place of a scientific team and equipment to detect any changes in underground activity that will precede the next caldera eruption.

You can download a USGS paper detailing the mechanisms for detecting and warning the public about “episodes of unusual geological unrest at the Yellowstone Caldera” at: http://pubs.usgs.gov/circ/1351. This sets up an Incident Command System, explains how the various personnel and agencies will be structured and will react with each other in the case of impending danger, and how the public will be kept informed. It also outlines specific scenarios for reaction to catastrophic events.

As for me, I won’t be writing blogs in the next while but will be enjoying favorite places and friends in and around Yellowstone.

All posts tagged geology

Yellowstone Rock Analysis 101

Reviews and Constructive Criticism, Part 2

One long review with a useful criticism

Counting the days

Yellowstone Volcano Observatory scientist not worried about an imminent supereruption

Supervolcano: are we ready for another caldera explosion?