Saturday, March 24, 2007

Thermochronic Book Club #1 - T.Rex and the Crater of Doom by Walter Alvarez

A while ago I blogged about how I would be challenging myself to read and blog about 5 popular science books over the course of the next year. I solicited suggestions, set a start date, and then, dropped the ball. There are two primary reasons that my geology blogging has been slack lately; first, I finally submitted a manuscript I've been working on, and second, it's NCAA March Madness time, the greatest American sporting event (by a long shot), and so have been a little distracted.

The paper took longer than I had hoped to submit, perhaps because to be honest I am not all that thrilled with it. The science is good, the data important, and the results make sense and need to be published, but for a number of reasons the results are not sexy nor earth-shattering. I know not all science is supposed to be ground-breaking, but still. At least it is out the door, we'll see what the reviewers say.

As far as the NCAA goes, those of you who don't follow or care about the Men's Basketball Championship tournament, during the first four days of the tournament, 48 single elimination games were played all over the country, resulting in some stunning upsets and nail biting finishes. I now live on the east coast of America, which means the games start late here, and finish late, so if I want to watch any I have to stay up past my bed time; this has cut into my other recreational activities (read: blogging).

But, I did finish my first book of the challenge, T. Rex and the Crater of Doom by Walter Alvarez.
I have been meaning to read this book since the 2002 Geological Society of America national meeting in Seattle where I saw Walter Alvarez receive the Penrose Medal. I had actually gone to the awards ceremony because at the same time, John McPhee was also receiving a medal (The GSA Public Service Award) and wanted to hear his acceptance speech. For me, though, Alvarez's acceptance speech really stole the show. I've been looking all over the internet for a transcript with no luck, but regardless, I remember it as being one of the more poetic and heartfelt speeches I had ever heard (especially at GSA). In his talk he briefly discussed the work he is most famous for (and the topic of this book), but more importantly spent time talking about the aesthetics of field work, and the importance of the friendships he had built over the years working on this project. I remember him ending with an image of the end of a field day, sipping wine in some perfect valley in Italy surrounded by friends and the excitement of the story they were all unraveling. Anyways, that was 5 years ago, and the fact that I am only now getting around to reading the book is a little silly, but here we go.

T. Rex and the Crater of Doom chronicles the events that lead to the discovery of evidence for a major extraterrestrial impact at the Cretaceous - Tertiary (or K-T) boundary, the time when all of the dinosaurs (and many other animals) suddenly went extinct, roughly 65 Million years ago. Alvarez began working on a series of limestones in the Appenine Mountains of Italy in an attempt to use paleomagnetics to chart microplate rotations in the Mediterranian. The section he was analyzing stretched over the K-T boundary, preserving an exceptional marine record of that time period. They never found evidence for microplate rotation, but they had stumbled upon something much more significant. What they eventually found was a huge spike in the amount if Iridium present in the clay layer at the K-T boundary. They published this finding in Science in 1990 (Alvarez et al., 1990, Iridium Profile for 10 Million Years of the Cretaceous-Tertiary Boundary at Gubbio [Italy]; Science v. 250, n. 4988, pp. 1700-1702). The Iridium concentrations were such a find because Iridium is not very common in the crust of the earth, most of the Iridium the planet contains is locked up in the core. Meteorites have similar bulk compositions to the earth, but can be completely destroyed upon impact, vaporizing themselves and leaving a fine layer of meteor dust spread around the world. Meteor dust is enriched in Ir compared to the highly differentiated earth crustal rocks, so it shows up as distinct spikes in abundance.

From Alvarez et al., 1990

This is a figure from the Alvarez paper showing the Ir concentration (in parts per trillion) versus stratigraphic position in the limestone. Background Ir levels are barely above the minimum sensitivity of the instrument, but at the K-T boundary there is an enormous peak. This "Iridium Anomaly" has since been found all over the world at the K-T boundary.

I don't want to give away the whole story, because the book is certainly worth reading. Alvarez does an excellent job capturing the process of science and presenting it for the readers in a way that is very interesting to read. It shows that what we find is rarely what we set out to prove, and that some of the most interesting and exciting scientific discoveries are born from the ashes of failed studies.

I've heard versions of this story many times during my geologic career, but the book still kept me interested. Alvarez adds enough background that the story is easy to follow (even for those with no real background in geology), without sounding too basic or redundant. These are qualities I think public science books need to have, especially when done in a genuinely readable style.

There are aspects of this book I found particulary interesting, but they didn't really center around the impact story. The first was his discussion of the tension in the geologic community over uniformitarianism. This idea is often summed up using a quote from Charles Lyell, "The present is the key to the past." Basically, if we want to know how something happened in the past, then we should observe today's processes. There is no need to involve "catastrophic" phenomena to understand geologic features, and that rare and catastrophic events (like impacts) have little role in the history of the earth. I had of course learned about this idea (which is still largely true, but I'll get to that in a minute), but the tension and disagreement over the importance of catastrophic events was something I never really had a feel for. This debate was happening during my lifetime, really during the beginning of my geologic education. The problem, as I see it, was that embedded in the concept of uniformitarianism is a time scale. Things that seem rare and catastrophic on the human time scale (large volcanic eruptions like Yellowstone, extra-terrestrial impacts, some of the floods that occurred when the dams of glacial lakes broke, etc...) are, from perspective of geologic time, fairly common. So it's not really that we have to call upon events that no longer happen, only that we have to expand the idea of everyday geologic phenomena.

The other aspect of the book I really enjoyed was his discussion of how geology, as a science, changed in nature from when he was doing his Ph.D.

Geologic mapping was satisfying and useful, but in retrospect most of it seems to me to have been intellectually pretty routine. While early twentieth century physicists were reading "the thoughts of God," in Einstein's phrase - exploring the majestic curvature of spacetime on the scale of the universe and disovering the weird quantum behavior of the infinitesimarlly small-geologists labored to reconstruct the paths of ancient rivers and the pattern of lands and seas at various times in the past.....Geology simply asked its apprentices to learn the techniques of geologic mapping and to memorize a lot of complicated terminology and then it sent them out to add to the growing knowledge of the rock record of the Earth.
And yet, with hindsight, we can see that the mapping was an investment which is now paying great dividends. Physics could make great discoveries quickly by reducing complicated problems to simpler components because physics investigates the fundamental laws of Nature, which do not change and do not become more complex through time. Geology seeks to understand the earth, which has evolved over 4,600 million years, accumulating more and more historical complexity in its rock record. That century and a half of mapping the Earth produced the detailed knowledge of the rock record which is now allowing geology to emerge as a mature science, skilled at interpreting historical complexity, and therefore perhaps the discipline best prepared to lead science into the holistic world of the twenty-first century. [emphasis added]


First, I'd like to point out that "that century and a half of mapping" is not really over. There are many regions of the world (even the continental US) that still need to be mapped (or remapped). It is a necessary step in understanding the geology of a region, and it introduces and refines most of the skills geologists need (primarly, it hones observational skills). Second, all geologists need to be able to create and read geologic maps, and any attempt to remove this from a curriculum is detrimental to the science. But, geology has changed. This is obvious to anyone who has checked out older theses from their university library; expectations are now very different. This is no surprise, I am sure all disciplines are similar, but I like to keep it in mind. I am tuned to lectures from people older than me about how easy younger generations have it, but that just isn't true. Expectations, abilities, and realities are all different. I suppose as I transition into a grumpy old man I should also keep it in mind.

The final aspect of the book I'd like to touch on is how well it describes what I think all geologists (perhaps all scientists) dream of happening to their research. You stumble upon something that ends up being enormous, and changes the face of science forever. There is no doubt that Walter Alvarez is an exceptional scientist who worked very hard for many years to accomplish what he did, but he also freely admits the role of chance in his discoveries. Things worked out well for him, and I think it instills hope that crazy and unforseen exciting discoveries are out there waiting to be made. Not in the project I finally submitted for publication, but I am sure they must be somewhere.

T. Rex and the Crater of Doom is worth the read, even if you already know the punchline. It is also rather short (which, Mrs. Apparent-dip-but-with-a-different-last-name can tell you is a key factor in my book-choosing process: I turned in 4 papers in 4 different classes on The Red Badge of Courage during my high school and college life).

I am not sure which book I'll be taking on next, but this is off to a good start. Any other thoughts on this book, or if anyone wants to comment on a recent paper by Gerta Keller et al. Chicxulub impact predates K–T boundary: New evidence from Brazos, Texas that appeared in Earth and Planetary Science Letters (Earth and Sanitary Appliance Letters?) Volume 255, Issues 3-4, 30 March 2007, Pages 339-356, I'd appreciate it.

7 comments:

Thermochronic said...

As was pointed out by Lab Lemming, I f'd up, the real first publication of the Ir data was in 1980, not 1990, the article I stole the figure from was a reprint, and I forgot to proof read.

Alvarez, L. W., Alveraz, W., Asaro, F., and Michel, H., 1980, Extraterrestrial cause for the Creataceous-Tertiary extinction: Science, v. 208, p. 1095- 1108.

Mil disculpas

Lab Lemming said...

In the spirit of shameless self-promotion, I'll offer up the following link:
Iridium anomaly as historical artifact

CJR said...

Good post/review. I've been thinking about writing something about the whole 'Uniformitarianism' misconception for a while - I've always put it down to a bizarre fixation on the details of a process rather than its driving forces, but I think you're right about the lack of temporal perspective. I'm not sure you haven't pre-empted me...

Brian said...

Thanks for the review.
I haven't read this book for a long time...but remember enjoying it. In fact, I gave it to my father as something to read for him to try and understand why we can get so excited about geology/science.

I read the original 1980 Science paper in a paleobio seminar last spring...very interesting to read within the context of other papers of the time. The paper comes across, like a lot of important papers do when read later, as very modest and nonchalant.

As for the uniformitarianism aspect, y'all should read this paper:

Gould, S. J., 1965, Is Uniformitarianism Necessary?, American Journal of Science, v. 263, p. 223-228.

Good stuff.

CJR said...

Gould wanting to diss uniformitarianism? Surely not...

Looks like an interesting read though, although the abstract indicates that, as so often happens in these debates, he's trying to push a good point too far.

Brian said...

The gist of Gould's paper...if i remember correctly...was that uniformitarianism could more usefully be subdivided into two types: methodological and substantive -- the former being what we as geologists think of in terms of process and the latter being that specific rates have never changed or varied throughout time, which is clearly not what uniformitarianism is about (but what creationist still spend their time refuting to make their point). The latter is what Lyell may have overemphasized in his time...perhaps justifiably so to boop the creationists...er, i mean catastrophists.

Gould makes the point that catastrophic events, which obviously leave their mark in the geologic record, fit just fine within the construct of methodological uniformitarianism.

Brian said...

As for the Gerta Keller paper...I haven't read it...but when I took this paleobio seminar last year, those in the field unanimously, but politely, scoffed at most of her work.

I don't know...i'm not in the field, but I got the impression that a lot of her previous papers are neither argued well nor backed up by sufficient data.