The Airliner Chronicles: Why are these Volcanoes Here?

A photo from my flight to a GSA meeting in Seattle a few years ago recalls a question that had different answers, depending on when you asked the question, or more like, no answers if you go back far enough in time: Why are these volcanoes here?

The subject popped up in my head as a result of the passing of one on of my professors this last month, Donald B. McIntyre. In reading some of the tributes to his life, I recalled that he had studied under Arthur Holmes, who was one of the pioneers in the acceptance of the hypothesis of Continental Drift, which was later refined into the theory of Plate Tectonics, an idea so radical that it pretty much rewrote an entire science (imagine if the chemists discovered an idea to replace atomic theory). Dr. McIntyre was actually involved in two revolutions of geology: he was also a historian who documented the life of James Hutton in several books.

It just happened that I had picked up and started reading Plate Tectonics: An Insider's History of the Modern Theory of the Earth, edited by Naomi Oreskes. It is composed of 17 essays by the researchers who uncovered the evidence for plate tectonics in which they remember the events in their own lives that led to the new theory. It is fascinating to learn what was in their minds during the 1950's and 1960's as the realization slowly dawned that what they had always accepted about the structure and history of the earth was not necessarily true. What happens when a bunch of young professors and graduate students stumble onto something that was both unknown and unimagined?

Reading these stories made me wonder about something else. What was it like to be a teacher or professor in the 1960's when the revolution of the science was at its height? I came on the scene a bit late to really know, taking my first class in geology in 1975, when plate tectonics was already becoming established in the classroom. If you were in the classroom in the 1960's, how much of the debate filtered into your curriculum? Was it a topic of discussion in classes, or was there even a realization that something big was going on in the science? I'm wondering what it was like for the people who weren't necessarily the pioneers at the forefront of radical research. Anyone want to contribute some thoughts and memories?

The picture is of Mt. St. Helens and Mt. Adams of the Cascade Range. These volcanoes are now known to originate from melting of the crust that occurs as ocean crust (and water) are carried beneath the continent at subduction zones. It was once thought that the extra weight of sediments accumulating on the edge of the continents pushed downwards on the crust to where the heat of the planet melted the deepest rocks.

Science Dies Ugly Death! Only 4 in 10 Americans believe in continental drift! (wait a second...)

Diagram of Pangea courtesy of the U.S. Geological Survey

Check out a poll and excellent discussion by Devilstower in which Research 2000 asked about plate tectonics (for DailyKos). Worded like similar polls by Gallup about evolution, they asked whether the respondents "believed" Africa and America were once connected ("Do you believe that America and Africa were once part of the same continent?"). If this sounds like a poorly worded question, it was, and they did it on purpose. First, look at the results:

YES NO NOT SURE
ALL 42% 26% 32%
DEM 51% 16% 33%
REP 24% 47% 29%
IND 44% 23% 33%
OTH/REF 42% 25% 33%
NON VOTERS 46% 22% 32%

WHITE 35% 30% 35%
BLACK 63% 13% 24%
LATINO 55% 19% 26%
OTHER/REF 56% 19% 25%

18-29 48% 20% 32%
30-44 40% 28% 32%
45-59 43% 24% 33%
60+ 39% 30% 31%

NORTHEAST 50% 18% 32%
SOUTH 32% 37% 31%
MIDWEST 46% 22% 32%
WEST 43% 24% 33%

Wording in a poll is everything, and for a long time major polling organizations have been asking badly designed questions about science, especially those on evolution, by wording their questions poorly, and then reporting the results with a misleading emphasis. Following the point made by Devilstower, a headline may very well read "Only 4 in 10 people believe..." but this ignores that fact that a full third of the respondents understood that they didn't have enough knowledge in the subject to give an informed answer. The real news in this poll is that only a quarter of the respondents were wrong in their perception of the science and that their ignorance was influenced by region, political affiliation and race (the interesting point in this poll result is how poorly whites did in comparison to blacks and hispanics, if you want to interpret the results literally).

Devilstower does a great job of explaining the inflammatory nature of the use of Africa in the question. Other questions in the poll were highly political ones, including an approval poll for congress and the president. It helps to explain the disparity of the findings in regards to the Southern states. Would the disparity still apply if Europe were substituted for Africa in the question?

The big problem with the poll is the use of the word "believe". People believe in deities. People hold opinions that animal testing is wrong. People believe it's wrong to torture prisoners. But does one believe in gravity? Can a person believe they don't need oxygen to live? They can choose not to believe these things, but it doesn't change the fundamental fact that they will fall if they jump off a cliff, or suffocate if they try breathing water. In the most proper sense scientists don't deal with beliefs. They deal with experimentation and confirmation of physical facts. Hypotheses can't be believed in, they have to undergo testing. They will usually be confirmed or disproven, and it doesn't fall to a vote about belief, whether by the scientists themselves, or by the public at large.

This misunderstanding about being able to pick and choose what science to "believe" is at the heart of issues like human-induced global warming or evolution. I have a lot of respect for the people who responded in this poll by saying they didn't know. I just hope they take the next step and try to learn something about it. Education is everything in facing the complex problems of our society.

Why I Teach - The Long Journey of the Australian Marsupials

If anyone wonders why I teach at a community college, and why I don't dabble much in research, it would be because I have a scientific version of attention-deficit disorder: as soon as I start concentrating on one subject, something interesting pops up somewhere else, and I explore it for a few weeks, and then get distracted by something else. My students love it; there is almost always some weird tidbit of information that will pop up in classroom discussions. And hopefully it is a disorder that works well with running an interesting geoblog.

I was reminded of this when I saw this article in National Geographic News (Ancient Lion With "Bolt Cutter" Jaws: Best Killer Ever?) about the Australian marsupial version of a lion(Thylacoleo carnifex). Apparently, the creature had one of the strongest bites of any carnivore, and those cuddly kangaroos once had a most fearsome predator in their midst. In fact, they had more than just one.

Generally, when students are presented with the biographical evidence for plate tectonics and continental drift, it involves a discussion of mammal-like reptiles, and the distribution of the glossopteris flora across the southern hemisphere. This makes sense, given the role they played in Alfred Wegener's fight to have continental drift accepted as a plausible scientific hypothesis.

On the other hand, the story of the marsupials is a fascinating tale of journeys across vast continents, incredible adventures in successful adaptation, and horrific tragedies of extinction in unlikely places and times, as well as the on-going extinction event that is seeing the probable disappearance of koalas, tasmanian devils, and others. After a discussion of which continent has been isolated the longest, most students guess Australia, on the basis that the continent hosts the most unique mammal ecosystem, the marsupials. I am then able to point out that the ecosystem was once much richer. For nearly every animal filling an environmental niche in the more familiar climes of Europe and North America, there was an equivalent creature in Australia. For the antelope and deer, there are kangaroos and wallabies. For mice and rats, there are opossums and marsupial mice. For cats there are quolls. A stretch, perhaps, but for pigs, there are wombats. For foxes, we find the Tasmanian Devil. Less than a century ago there were Tasmanian wolves (hunted to extinction by 1930). In the paleontological record, we find a 3-ton marsupial buffalo or cow equivalent (diprotodon), and the subject of the linked article, the Marsupial lion, Thylacoleo carnifex. There was even a carnivorous species of kangaroo (Ekaltadema ima)!

The next obvious assumption is that marsupials originated in Australia. Why not? It makes sense that the most complex ecosystem of marsupials on earth must have arisen on the continent where they are found today. But they did not originate there, and were in fact relative late-comers to Australia.

The oldest marsupials known are reported from China, from Mesozoic time. My students immediately assume these marsupials got to Australia via the Indonesian Islands, which brings up the Wallace Line, which is a clear demarcation between many kinds of animals that exist on either side. The concept dates from the 1800's, and is in fact the work of Alfred Wallace, of evolutionary theory fame. The reason is tectonic. The continents are currently moving closer, and have been much further apart, making island-hopping essentially impossible.

Instead, the fossil records chronicles the successive arrival of later marsupials in North America, South America, Antarctica, and finally Australia. The distribution of these creatures makes no sense if the continents are stationary: they couldn't and wouldn't swim such distances. Instead, the journey of the marsupials is a fascinating line of evidence that supports the one-time existence of Pangea, Laurasia and Gondwana. And the story doesn't end there...

South America once supported a thriving marsupial ecosystem, including a marvelous example of convergent evolution in the existence of a sabertooth marsupial cat. It survived until around 4 million years ago, when the isthmus of Panama linked north and south America, allowing predators, especially the big cats, to move south, and treat South America like a giant buffet. The marsupials were decimated for the most part. On the other hand, the marsupial rat (the Virginia opossum) thrived in competition with North American placental species, and expanded its range into the United States.

It is a privilege and a joy to be a teacher. I've been thinking about this month's geoblogosphere carnival (subject, "what things make us go hmmm?"; see http://lablemminglounge.blogspot.com/2008/01/accretionary-wedge-5-and-6.html). I may end up with wondering what it is we do to destroy a student's sense of wonder about all things scientific. More to come....