of lakes and rocks (or why I do what I do)

I grew up on the second-most-polluted lake in the state of Maine. It was nasty – it looked like pea soup, and it smelled like rotting vegetables. But it was also beautiful – blue reflections from the sky, green trees hiding the houses on the other side, eerie cries of invisible loons in the evening and morning. There was a big rock, just right for sitting on, out where the water was about four feet deep. On the beach, there were shiny flat pebbles just right for skipping, and little sand grains that stayed stuck to my feet, even when they were dry.

The lake’s problem stemmed from years of being over-fertilized – sewage from two upstream towns was poorly treated, houses around the lake had leaky septic tanks, and rumor has it that there used to be a potato chip factory that dumped peels into the lake. By the 1970’s, it was a prime example of a eutrophic lake, a lake that had gone scummy and bog-like before its time because of too many nutrients and too much algae.

My dad started working on the lake’s problems in the early 1970’s. He’s a mathematician, and he worked with a geology grad student to develop a computer model of phosphorus cycling in the lake. I didn’t experience the modeling (well, other than scribbling on used punch cards), but I did get to help with the water sampling a few times. Mostly I sat in the boat and watched them collect bottles of water and lower a secchi disk until they couldn’t see it any more. But it made an impression on me. I remember bringing a little bottle of water and zooplankton for show-and-tell in 2nd grade. And by the time I was in high school, the research had turned into an experiment in cleaning up the lake. There were some new sewage treatment plants built (eventually – one town finally built its new one just a couple years ago), but the big experiment was the new dam. The town excavated the lake’s outlet and, every fall, lowered the lake by more than 10 feet, in hopes of flushing the phosphorus downstream.

I was impressed (though I didn’t think through the implications of sending the problem down to the Kennebec River and the Atlantic Ocean). I was impressed enough to have megalomaniac 10-year-old dreams of becoming a scientist and figuring out how to make chemical reactions run backward and solve the world’s pollution problems. (I hadn’t studied the 2nd law of thermodynamics then, obviously.)

When I went to college, I wanted to study environmental chemistry. But there was a freshman seminar offered on environmental geology, and intro chemistry wasn’t offered until winter term, so I took geology to have some fun and kill off my writing requirement.

And I got hooked.

Field trips. We walked along the river and talked about currents and sediment and erosion and floods. We went down to a park and made geologic maps of flat-lying sedimentary rock by coloring along contour lines. (Did I happen to mention that I went to college in the Midwest?) The horizontal bedding, actually was a huge revelation. I had grown up in a world full of glacial erratics and widely spaced outcrops that had no obvious relationship with one another. The idea that rocks could be correlated from one outcrop to another astounded me. And beyond that, rocks were laid down flat. I can hear the people laughing already when I say this, but the priniciple of original horizontality was probably the single biggest revelation of my introductory geology class. (Well, that and plate tectonics – I had taken an earth science class in high school, but the textbook was outdated, and even in 1981 I got the impression that continental drift was some wacko idea that had been mostly discredited.)

Our final project for the class was to write about the geology and landscape of my hometown. That was the first time I ever looked at the geologic map of Maine. I didn’t understand it, and wrote about the location of my hometown on a drainage divide between two major river systems. But when I went home for winter break, I started noticing the rocks. In particular, I noticed one road cut on I-95, just outside Bangor. It was made of phyllite, and it glistened even when it was dry. And the layering was vertical.

If rocks started with horizontal layering, and the rocks around Bangor had vertical layering, then... something really cool had happened there, practically in my backyard. And I wanted to know more about it.

Chemistry was pretty much doomed as far as I was concerned. I held on to dreams of being an environmental geochemist for years – I monitored water quality as part of a campus job, I applied to grad schools with low-temperature geochemistry programs, and I worked for the USGS on a project dealing with mitigation of acid mine drainage. (And I kept taking chemistry classes, though physical chemistry.) But the rocks kept calling. Not just any rocks. Rocks that had been through a lot and had stories to tell. Rocks that had been buried, contorted, heated, transformed. Rocks that were once under the equivalent of the Himalayas (120 million years ago, or 380 million years ago, or 1.7 billion years ago). Down a subduction zone. Stretched and thinned in a metamorphic core complex. Baked in the aureole of a pluton. Metamorphic rocks are the survivors of geology. They have been through it all, and it has changed them, but they haven’t melted or broken apart.

And I like to know their stories.

Oh, and the rocks on the beach where I grew up? The sand grains and skipping stones were phyllites, and the big rock in four feet of water was a granite boulder. There were pebbles with andalusite in them, too, probably from the aureole of one of the granites or another. So I may not be studying lake water, but my rocks still remind me of home.