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Temporal Reasoning in Geosciences

Claim, Evidence, Reasoning. One school of thought in science education places great emphasis on fostering students' ability to articulate a claimabout an aspect of the world, back up that claim with evidence, and construct a coherent line of reasoning to show that the evidence does indeed support the claim.

In geology, the evidence often has to do with the timing, or sequence, or rates, of events in the past. Dozens of geologist-lifetimes have been invested in figuring out to constrain what happened at what time in earth history. And then thousands of geologist-lifetimes have been invested in using these techniques to attach dates to bits of rock or mud. Geology students spend entire courses learning to think about dates, times, and ages, via fossils, via magnetic signature of rocks and mud, via stable isotope ratios, via unstable isotope ratios, via geometry of cross-cutting relationships.

So what is the big deal about dates and ages? Why spend so much time and effort on these factoids? More

Through a Lens Darkly and Then Face to Face*

I've been hiking every Sunday this past fall with a group of geology majors--the Sunday Hiking Club. We are doing a service-learning project to create trailside posters and websites that explain the natural history of popular trails in the mountains surrounding our town. While on our hikes, all of the students are taking digital photographs of their experiences on the trail, and the archives of these images will serve as the raw materials for the story lines we'll present to the public. At the simplest level, our trailside posters will help direct the attention of interested hikers to the wonders they'll encounter along the trail. The premise is that the hike may be a bit more enjoyable and meaningful for recreational hikers if they know what special features to look for along the way. For the hiking public, their original motivation for going on the hike may range from exercise to aesthetics, but we think we can slip in a little science education along the way. The accompanying websites will be a bit more detailed, with in-depth information for further personal investigation with resources such as geologic maps, articles that are accessible for reading by the public, archives of annotated images, and links to related instructional sites. In observing Nature through my own lens, and also observing my students as they themselves look at the world with focused attention through their cameras, I came to realize vaguely at first, and then with increased clarity, the transformative power of photography as an instructional activity. More

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Extrapolating Beyond the Last Data Point

In followup to our recent EOS paper "How Geoscientists Think and Learn" (Kastens, Manduca, et al, 2009), Michael D. Max, of Marine Desalination Systems, wrote:

I think this is an interesting point, that extrapolation beyond the last data point is more or less forbidden in science, but geologists do it anyway. More

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