For geologists, professional and amateur alike, it’s simple. It’s the rock below our feet and the rock towering over our heads. It’s the physical and chemical processes that gave these rocks their distinct textures and flavors, and the tremendous forces that shape(d) them. The biotic veneer that selectively coats the crust is fascinating and often beautiful in its own right, but for a geologist, it’s all about what’s underneath that counts.
My apologies for waxing philosophic. I’ve got all this on the brain after returning from a long weekend of road tripping through the Cascades with two close friends—one a structural geologist and the other a seismologist. What better way to see the mountains, right? It’s like having a backstage pass: you get the insider’s scoop, far more interesting than the average self-guided tour. Okay, so my friends aren’t the world’s foremost experts on the Cascades. Nor are they park rangers who could sneak us up close and personal to the steaming vents of Mt. St. Helens. Nonetheless, they are very bright, and they know a whole lot more than I do about these things (I was, after all, only a biogeochemist, as they jokingly remind me on occasion).
The trip, initially just a work excursion for the seismologist, grew to road trip status when he suggested that the structural geologist and I join him after his official obligations were finished. Spontaneous travel through beautiful country? Seeing the Cascades in person for the first time? A chance to visit other friends on the way? It was an easy sell.
Our route took us from Portland, out and back around Mt. Hood, through the Columbia River gorge, and up to Seattle with a detour over to Mt. St. Helens. From Seattle, we also drove east among the snowcapped mountains for a day trip to Stevens Pass. It was a fantastic time, and I’d recommend a similar route (minus the stretch on I-5) to anyone who enjoys looking out the window on long car rides. Just be forewarned, if you travel with geologists, you’re likely to encounter some or all of the following, as I did:
1) Mandatory roadcut stops on the side of busy highways: As John McPhee wrote in Basin and Range:
“Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrane.”
Better to stop and look at the proscenium* arch than to risk lurching and weaving past it. Oh, and don’t forget to collect hand samples.
(*Proscenium: “The area of a modern theater located between the curtain and the orchestra.” Thank you American Heritage Dictionary.)
|The structural geologist (left) and the seismologist doing what|
they do: checkin' out a roadcut near Mt. Hood, OR.
2) Allusions to John McPhee: Inevitable
3) Fun factoids: The joints in columnar basalt form perpendicular to the cooling front.
|Columnar basalt, also near Mt. Hood. Sweet!|
4) Detours off the beaten path: Say, for instance, up a Forest Service road, past a large ‘Road Closed’ sign.
5) Way more information than you thought you’d get in response to a question:
Example: “Why do geologists measure gravity?”
Answer (paraphrased and heavily edited): “It involves measuring deviations, or anomalies, from the expected gravity at the earth’s surface (the geoid) given that the acceleration due to gravity at the surface is roughly 9.8 meters per second squared. It’s not as simple as that, though. A lot of corrections have to be made. For one thing, the earth is not perfectly spherical, it’s slightly wider across the middle than it is from pole to pole, so the ideal expected gravity varies depending on where you are on the surface. You also have to apply a free-air correction that is correlated with elevation because the gravity decreases with distance from the center of mass. But then you have to apply the Bouguer correction to account for the effect of the increased (or decreased) mass of rock at higher (or lower) elevation.” And so on...
Rough Translation: To determine the subsurface density of rock in a particular location.
6) Informed (?) speculation: About everything from rock ages to cloud formations to how Lady Gaga is the modern incarnation of Madonna.
|What a funky looking cloud.|
Lest I never get invited along on another road trip, I must admit that I wasn’t merely a passenger in all this. I was as eager to stop at roadcuts, analyze hand samples, and make questionable detours past forbidding signs as they were. I too am intrigued by columnar-jointed basalt (It’s like Play-Doh! So weird.). And though the structural geologist apologized for his 10 minute lecture on gravity measurements in lieu of simply saying “density” (which, incidentally, is how the seismologist answered my question), he had my undivided attention.
Ah, the joy of road tripping. With geologists, of course.