geology

Here in paleoanthropologyland, we are often subject to the whims of the nomenclatura. These folks come up with new "logical" ways to name things, and we either have to adopt the new name or risk looking like outmoded dorks. That's more or less what has done in the term "hominid" -- if you're "with it", you call them "hominins" instead (of interest may be my 2005 review of the hominid-hominin problem).

I have approximately the same respect for this process as I do for the "Pluto is not a planet" crowd. I have no problem with the fact that some people know the system and use it effectively. But I think the scale out to be weighted against fads and in favor of conservativism in the names of things. After all, who is to say that we won't discover tomorrow a line of quadrupedal apes that are co-laterals to the australopithecines? If they're hominins, too, doesn't that mean we'll need another name for the australopithecine-human clade? There's no end to the literature changes we can initiate.

Well, that's not what has me riled up. On Nobel Intent, John Timmer writes:

Is the Anthropocene a new geological epoch?

These days, there seems to be a steady stream of species, from bats to bees, suffering from population collapses. In some cases, like fish, the cause is obvious; for others, like amphibians, the underlying cause (causes?) is less clear, but items such as environmental stresses and invasive species make for reasonable candidates. It's easy to wonder whether humanity's impact can really be so comprehensive, but there has been one sign that it is: geologists are seriously considering the possibility that we've triggered a new geologic epoch, which some are calling the Anthropocene.

I've seen the term appearing in a number of papers recently, and decided to look into it. It appears the term was only coined about six years ago, but it's gained serious credibility within scientific circles. Perhaps the most detailed treatment of the topic was published earlier this year in a member's journal of the Geological Society of America.

Silly me. I thought we already had a name for this: the Holocene. That's the geological epoch that began 10,000 years ago, with the recession of the last Ice Age. It was during the early Holocene that some human groups became agriculturalists and started exerting large-scale changes on local and regional environments. Domestication of animals and the consequent displacement of wild herbivores was a Holocene phenomena. Human-caused burning of dry woodland-grassland habitats was essentially Holocene (although in some areas it began earlier). The transformation of tropical forests by swidden (slash-and-burn) agriculture: Holocene.

All these things did not begin at once, they stretched over 10,000 years. But the most important thing is that they didn't start at once. They started over the course of the last 10,000 years. There's no reason to call this time period a new name like "Anthropocene." Holocene covers it nicely.

Timmer points to a paper from earlier this year describing the concept of "Anthropocene" and supporting evidence. The logic, from a geological standpoint, is that human activity may have altered sedimentation (by damming major rivers and accelerating erosion) and faunal and floral communities in a way that would be recognizable in a stratigraphic sequence. In other words, recent human activity may generate a stratigraphic boundary as distinctive as the K-T or Permian-Triassic boundaries.

The paper concludes:

Sufficient evidence has emerged of stratigraphically significant change (both elapsed and imminent) for recognition of the Anthropocene—currently a vivid yet informal metaphor of global environmental change—as a new geological epoch to be considered for formalization by international discussion. The base of the Anthropocene may be defined by a GSSP in sediments or ice cores or simply by a numerical date.

This is my problem: Since when did we make scientific decisions based on "vivid yet informal metaphors"? Sure, there are many scenarios for what may result from human action, including what has already happened, that put it on the scale of past geological changes. But this should be an empirical decision, not a speculation. In that respect, even the Pluto decision was better than this idea, because it was rooted in an empirical observation -- many hundreds or thousands of objects might ultimately be identified as planets, which raises the practical problem of naming and delimiting them. There was the obvious choice of referring to "the traditional nine planets," or instead of redefining "planet".

Here, we have a possible empirical consequence of current activity -- maybe someday the differences in sedimentation at the Industrial Revolution will be important enough stratigraphic divisions to merit global rather than merely local recognition. And a small group of geologists, specialists in defining boundaries of time periods, are pushing the idea.

I think that if these folks are going to define geological periods based on the impact of human behavior, that they really should consult with anthropologists and archaeologists. My own opinion is that the Industrial Revolution is merely an amplification of processes begun much earlier, and that its most important geological effects (like damming) are local. There is an argument that the faunal and floral exchanges (and to a lesser extent, extinctions) are globally recognizable, but it seems doubtful to me that these can be meaningfully limited to a period shorter than the Holocene, since widespread animal exchanges are as early as dogs and dingos.

In the end, the rest of us working in fields where the time periods are important will live with whatever consequences. And schoolkids learning the geological history will read about how the Industrial Revolution is formally recognized as an event on the scale of the K-T extinction. I am concerned that the main impetus behind the name "Anthropocene" is as a subtle means of gaining political traction. In that sense, it leaves me with the same feeling as "hominin" -- which in the end has been yet another way to beat the dead horse of human "uniqueness".

A local story:

MILWAUKEE - A 76-year-old Kenosha County man in whose cornfield the skeleton of a mammoth believed to be about 12,500 years old was dug up in 1994 is interested in selling it, and officials of the Milwaukee Public Museum are interested in it.

He's got the mammoth in wooden crates in his basement.

Experts have suggested the bones could be worth from between $100,000 to $500,000.

...

Hebior [the owner] said an effort to sell the bones several years ago failed because the bids that came in were too low.

A number of Siberian mammoth skeletons sold after the fall of the Soviet Union might have suppressed the market, said Dan Joyce, senior curator of the Kenosha Public Museum.

That gives a whole new meaning to "bioprospecting!"

This is a neat story:

GREENSBURG, Kan. - Scientists located a rare meteorite in a Kansas wheat field thanks to new ground penetrating radar technology that some day might be used on Mars.

The dig Monday was likely the most documented excavation yet of a meteorite find, with researchers painstakingly using brushes and hand tools in order to preserve evidence of the impact trail and to date the event of the meteorite strike. Soil samples were also bagged and tagged, and organic material preserved for dating purposes.

Even before they had the meteorite out of the ground, the scientific experts at the site were able to debunk prevailing wisdom that the spectacular Brenham meteorite fall occurred 20,000 years ago. Its location in the Pleistocene epoch soil layer puts that date closer to 10,000 years ago.

The "Brenham" meteorite was a 450 kg specimen found in 1949, and pieces of the same impactor are all over the county. An even bigger chunk was found last year only a mile or two away, and it was the third biggest of its type ever found. This is another piece of the same rock, but found in the ground so that they can date it.

I find it interesting that here we have a highly dispersed resource, which probably occurs with nearly equal probability anywhere in the world, but very rarely. So a few people have specialized to find them, because they are scientifically interesting and worth a lot of money. And they used to be limited to looking in places with lots of permanent ice (where melts made them easy to find on the surface) or places with very little vegetation, like deserts, where -- again -- they are stuck on the surface.

But technology has made it possible to find them in a broader range of contexts, so it's an open field for searching. Of course, in this case there's a reason to look harder, since there are fragments of the same ancient meteorite all over the county.

Mars and the moon are in conjunction tonight, as I happened to notice outside. With a full moon they are a spectacular show.

Sometimes it takes actually seeing celestial bodies sidling up to each other to remember that they are out there, pulling on the sun like buckets on the end of a rope. Except the moon -- it is pulling on us, sluicing the tides around the world. Now Mars is near opposition, and from here it will slide a bit farther west every night until it reaches the sunset. And all this because we are overtaking it, because we are swinging faster in our orbit around the sun.

I have a clear mental image of the full moon -- usually the full moon rising over the eastern horizon or low in the southeastern sky. In that position it seems the biggest, and you read all the time about why the illusion of a larger moon seems so real.

But it takes seeing the moon next to a planet, way overhead, to realize there's something wrong with the image. When you see the rising moon, you're looking at it sideways, with the north pole on the left. When you look at the moon right overhead, with your head in the north, it looks a bit unfamiliar, a bit strange. That's the way it's spinning, once every time it revolves around us.

And every time it goes around us, it goes a tiny bit slower, like a spinning figure skater letting her arms out. Because that's exactly what's happening; it's getting a bit farther away.

Mars is a bit further from us at this opposition than the last one, 26 months ago. Then, it was very near perihelion, and close to the sun means close to us as well. In fact, it was closer in 2003 then at any time in the last 59,000 years. NASA even commissioned an artist's conception of a Neandertal family watching it.

Of course, you know the Neandertals are stupid because they are looking away from the red orb in the sky.