Archive for the 'Geology' category

Catastrophe or Uniformity? One Earthquake, Two Opinions

Apr 11 2011 Published by under Geology

At 11:37 pm on August 17, 1959, a magnitude 7.5 earthquake struck near Yellowstone Park. At the time, there were two geologists from the United States Geological Survey who were doing fieldwork in the area, and who were living in a camping trailer near the epicenter. The earthquake had a strong impact on how each of the two thought about their field, about how the earth operates, and about the longrunning geophilosophical debate between the uniformitarians and the catastrophists.

If you spend any time doing geology, you hear something about uniformitarianism and catastrophism. Uniformitarianism, we are usually told, basically means that the earth functions now more or less the way it always has. Catastrophism, by contrast, is the belief that the history of the earth has been shaped by a series of catastrophic events. The conventional wisdom holds that uniformitarianism kicked catastrophism's ass back in the mid-nineteenth century, but the catastrophists began staging a bit of a comeback in the 1980s, as we began to better understand the role of big flying rocks in the history of life.

Back in the late 1990s, I spent a couple of years working as a contract lab tech at the US Geological Survey's headquarters in Reston, Virginia. The USGS has a spectacularly good library there, and I've always been interested in history, so I spent quite a bit of time down in the basement reading through Victorian-era books and journals. Somewhere along the way I developed a particular interest in uniformitarianism and catastrophism, and I started to wonder what opinions - if any - the geologists on my team had on the topic. So I wandered around the halls and asked quite a few. As luck would have it, both of the geologists who were sitting in the camp trailer when the 1959 quake hit were still hanging around.

One of the geologists in question was Anita Harris. The views she expressed to me were (unsurprisingly enough) very similar to what she told John McPhee, when he traveled with her for his book In Suspect Terrain:

As the night returned to quiet and the ground ceased to move, Anita recovered whatever composure she had lost, picked up her deck of cards, and said to herself, "That's the way it goes, folks. The earth's a very shaky mobile thing, and that's how it works. Apparently, the mountains around here are still going up. Later, she would say, "We were taught all wrong. We were taught that changes on the face of the earth come in a slow steady march. But that isn't what happens. The slow steady march of geologic time is punctuated with catastrophes. And wat we see in the geologic record are the catastrophes. Look at a graded sandstone and see the bedding go from fine to coarse. That's a storm. That's one storm - when the water came up and laid the course material down over the fine. In the rock record, the tranquility of time is not well represented. Instead, you have the catastrophes. In the Southwest, they live from one catastrophe to another, from one flash flood to the next. The evolution of the world does not happen a grain at a time. It happens in the hundred-year storm, the hundred-year flood. Those things do it all. That earthquake made a catastrophist of me."

The earthquake made a catastrophist of Anita. But for her then-husband Jack Epstein, it reinforced his understanding of uniformitarianism. I don't have John McPhee's skills as a writer, and I didn't take great notes when I talked to Jack. But the ones I did take are more than enough to refresh my memory of what he told me.

When I asked him about uniformitarianism, he told me about the earthquake. That earthquake, Jack told me, is uniformitarianism in action. It's a big event to us, but not to the planet. The mountains, Jack pointed out, are the result of no one earthquake. They're the product of earthquakes and storms, some pushing up, some washing down, over huge periods of time.

One earthquake. Two geologists. The earthquake makes a catastrophist of one, and confirms the uniformitarianism of the other. What does that tell the rest of us?

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Picture of the Day - 13 January 2010

Jan 13 2010 Published by under Geology

When lava flows through forested areas, you sometimes find holes like this:


Tree Mold

Hawai'i Volcanoes National Park

4 November 2006

1/180 @f/6.7; Pentax *ist DS; zoom lens at 18mm

When the lava hits trees, it begins to cool and harden almost immediately. The trees burn, but this can take a while, even in the middle of a lava flow. The end result is seen in the picture above - a tree shaped hole, known as a tree mold, that preserves the shape and occasionally even the surface texture of the tree.

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How thoroughly have we examined the fossil record?

Jan 11 2010 Published by under Basic Concepts, Geology, Science

The big paleontological news of last week was the announcement that fossil footprints have been discovered that predate - by about 20 million years - the previous contender for the earliest fossil evidence of tetrapods. Naturally, this announcement led almost immediately to a new round of "learning anything new about evolution means that Darwinism is totally wrong" claims from the Creationists.

Their complaints don't impress me much. There's very little difference between the Discovery Institute's "if there were tetrapod footprints 20 million years before Tiktaalik, how can something Tiktaalik-like have been an ancestor to tetrapods" line and the far older "if we descended from apes, why are their still apes" canard. If you're interested in another explanation of why you shouldn't be bothered by having ancestors and descendants alive at the same time, PZ's written a good one. I'm going to look at a different question.

It seems like someone finds some new fossil form somewhere every couple of years that changes our understanding of the evolution of some major group of plants or animals. Paleontology has been a serious scientific pursuit for the better part of the last two centuries. How is it that we continue to make so many spectacular new discoveries? Shouldn't we be at the point where we're just filling in the little gaps in the fossil record?

How thoroughly have we actually examined the fossil record? How much rock have we actually looked through in our quest to understand the evolution of the major branches of life?

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Are Republicans largely anti-science, or just largely ignorant? We report, you decide.

Aug 07 2009 Published by under Geology

A friend just pointed me to this... illuminating bit of polling data on the Daily Kos website:

QUESTION: Do you believe that America and Africa were once part of the same continent?

24% of Republican respondents answered "yes". 47% answered no.

That's right - Republicans rejected plate tectonics by about a 2:1 margin. Words seriously fail me at this point.

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Redoubt Eruption - As Seen From Space

Mar 26 2009 Published by under Geology

As many of you probably know by now, Alaska's Redoubt volcano has been erupting for several days now. If you're interested in the details, head over to new SciBling Erik Klemetti's Eruptions blog. If you're interested in the latest in really cool pictures, here's one for you:

1238107943 Ak231

(Source. Click for full size version)

The picture comes from the Alaska Volcano Observatory (aka place where "something called volcano monitoring" gets done). The ash plume from the eruption is the clearly visible dark smudge near the center of the picture. The image was taken by a weather satellite in geostationary orbit over equatorial Asia.

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A Fossil Fetus and what it can tell us about the life history of early whales.

Feb 03 2009 Published by under Biology, Geology, Science
An article published tonight in the journal PLoS ONE is forcing scientists to rethink everything they thought they knew about whale evolution.

OK. That's not actually true. But I've got a bet going that "someone" is going to use the phrase "rethink everything" in their story about this find, so better safe than sorry. Plus, it's a way cooler lede than "new whale fossil discovery matches predictions beautifully", even if the mundane description is the one that's just the tiniest bit more accurate.

Seriously, though, a multinational team of authors led by University of Michigan rock star Philip Gingerich is reporting a huge paleontological find - a fossilized pregnant early whale. It's the first time that an early cetacean has been found with a fetus. They also report finding the remains of a male of the same species. This combination of fossils - male, female, and fetus - is absolutely fantastic, because it provides information about so may different parts of the life history of this species.

Since one of the fossils found was a pregnant female, the researchers have named the new species Maiacetus inuus. The Maiacetus part of the name comes from the Greek for "mother whale". The inuus comes from the ancient Roman god Inuus, who was apparently the deity who handled (so to speak) sexual intercourse. That conjugation of names might be a bit unfortunate. It isn't as bad as some I've seen (Amorphophallus geei immediately springs to mind), but it does look like one possible translation of this whale's name would be "holy mother whale...

But anyway.

The fossils in question were found in 2000 and 2004, in an area of Pakistan that's already taught us a great deal of what we know about early whales. The newly-reported remains date to the early middle Eocene epoch (about 47.5 million years ago). This was a really interesting period in whale evolution, because it was a time when whales had not yet become fully marine organisms.

The skeleton of the male is the most complete of the three, and provides the best view of what the animal would have looked like while alive:


Artist's conception of male Maiacetus inuus with transparent overlay of skeleton. (Click to enlarge)

Credit: John Klausmeyer and Bonnie Miljour, University of Michigan Museums of Natural History

image courtesy of PLoS

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Global Warming, The Carbon Cycle, and Fish Poop.

When we talk about the role of fossil fuels in climate chance, what we're really talking about is the carbon cycle. That's the term that scientists use to describe the different forms that carbon is stored in on the earth, and the different ways that it can move from form to form. Understanding the carbon cycle is one of the keys to understanding both the effect of burning carbon-based fuels and the issues involved in trying to take carbon dioxide out of the atmosphere. According to a paper in the latest edition of Science, there may still be some pretty significant gaps in our knowledge of the carbon cycle. In particular, it looks like our understanding of the way carbon moves through the oceans may have been suffering because we didn't know poop about fish poop.

Before we get down to the gritty details and talk about what poop has to do with anything, it might be good to start with a quick review of the carbon cycle. Actually, it might be even better to start with a quick review of one of those concepts that we all learn in third-grade physics, but don't think about much in our day to day world: the law of conservation of mass/matter.

Matter is not created or destroyed. Therefore the amount of mass in a closed system will remain constant no matter what happens.

Like most things in science, that might be a bit of a simplification, but when we're looking at something the size of the Earth, it's good enough. Relativity, quantum mechanics, and space dust might all complicate things a bit, but not enough to matter. For our purposes, we can reasonably assume that all the carbon that we're putting into the atmosphere in the form of carbon dioxide has been here since the earth was formed, and that if we want to take the carbon dioxide back out of the atmosphere, we're going to have to find somewhere on this planet to store the carbon.

With that in mind, let's look at the some of the more important ways that carbon can move through the crust, oceans, and biosphere, and atmosphere.

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23 responses so far

Assessing Diversity in the Past

Jan 24 2008 Published by under Biology, Geology, Science

Blogging on Peer-Reviewed Research

Over at Evolving Thoughts, John Wilkins has a post that criticizes a recently-published journal article. Normally, I agree with John - in fact, if it's true that the best measure of someone's intelligence is how often their views match yours, then John Wilkins is an absolute genius. But even Einstein had off-days, and (again, based on the agreement standard) I think this might have been one of John's.

The article in question, by paleontologists Sarda Sahney and Michael Benton, examines how long it took for ecosystems to recover after the end-Permian extinction. The dinosaurs weren't around then, so the end-Permian doesn't usually get the attention that the end-Cretaceous does, but it was by far a much more significant event. By some estimates, more than 95% of all animal species went extinct at that time. John's main complaint is with the way paleontologists compute estimates like that, and I'll explain why his objections are a bit on the idealistic side later on. First, let's take a look at what the authors did, what they found, and why their results are way cool.

When scientists study mass extinctions, they are usually interested in one of two things: what happened to cause the extinction, and what happened after the extinction. Both of those questions are important, not just because they help us understand what things were like millions of years ago, but also because they can help us better understand the potential consequences of some of our actions right now. In this study, Sahney and Benton are focusing on the second question. They want to know how long it took for new species to evolve and re-establish the level of diversity that was seen in terrestrial tetrapod ecosystems before the Permian extinction.

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Dinosaurs, Birds, Feathers, and Conodonts (Oh, My!)

Most of the readers of this blog are intelligent, interested, scientifically literate individuals, but I'm guessing that at least a few of you aren't familiar with one of the nouns in the title. Those of you who do know what a conodont is are probably wondering what it has to do with the others. If you bear with me for a little bit, the connection will be clear shortly. It has to do with fossils, fossilization, and the latest spectacular misunderstanding of those two things at Uncommon Descent.

Conodonts are (or, rather, were) an interesting group of animals. They were around from late in the Cambrian period until the end of the Triassic, and were quite common during most of the period. They're not well known to most people outside of geology because the vast bulk of the evidence we have for them consists of very tiny tooth-like fossils. Most are only a millimeter or two in size, and are very hard to see without a microscope. They've received a lot of attention from paleontologists over the years because they're very useful little critters, particularly for geologists who work in the oil and gas industry. The thing is, for a long time nobody knew just what sort of critters they actually were.

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Today's Indian Ocean Tsunami, Small Tsunamis, and The Tsunami Warning System

This is a continuation of a post I wrote (and updated a couple of times) earlier today. Since the tsunami is no longer a possibility - it's an actual event - I thought a new title was probably a good idea. Here's the situation as it currently stands:

The Pacific Tsunami Warning Center issued a final watch statement for the event at 11:05 am Eastern time. They report that a tsunami was generated, and is currently traveling across the Indian Ocean. Based on the data that they have - currently, they have readings from three near-shore tide gauges and one deep-ocean gauge - the tsunami is small, and is not expected to cause damage in distant areas. (It should be noted, however, that PTWC's message also notes that they still only have limited access to sea level data in the Indian Ocean, and that they might be wrong about that.)

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