How We Saved the River; or, A Battle with Nature
October 4, 2010 Comments Off on How We Saved the River; or, A Battle with Nature
This weekend was my sed/strat field trip to Warren Dunes State Park, MI. It was cold and windy and sometimes rainy and I didn’t bring enough clothes to sleep in, but other than that, it turned out pretty well. The major highlight was breaching the dam and watching the beach get destroyed.
Allow me to explain.
The steady winds hitting the southeastern corner of Lake Michigan have been constant for long enough to pile up water against the beach there—the water is actually much higher at the downwind end than at the upwind end. This is called a seiche. As waves come in to shore, they tear up a ton of sand and carry it up onto the beach, where they lay it down in thin layers that accumulate pretty fast. Because this seiche was so big, the waves built a berm, or rise, significantly faster than normal, and ended up damming the mouth of a little river. It ponded over a very large area of the beach when we were there on Saturday.
The river-fed pond kept rising higher and higher, and eventually, our professor (pictured) told us, it was going to overflow the berm and slice down to its normal course. It was going to be dramatic and amazing. We waited all day long with bated breath, even coming back to check on it after dinner. We went to bed disappointed, sure it was going to break during the night.
It didn’t, but by Sunday morning we were frustrated. We were going back to Madison that day and, dammit, we wanted to see some dramatic fluvial incision. So we took matters into our own hands.
Anyone who remembers how much fun it was (is) to mess with water, either in a creek, a bucket, or the runoff from your neighbor washing his car, should be able to imagine what intense amusement we derived from this experience. We only worked the trench until it was a foot or two wide…after that, it was just the power of all that backed-up water. The sides kept collapsing—big cracks formed along the sides of the channel, and really significant chunks fell into the water, to be instantly swept away. It eventually got even deeper than in the last picture above, so that if I had stood at the lowest point, the tops of the incised banks would have been at the level of my head. The drop in elevation between the level of the pond and the beginning of the channel was surprising.
And it was beautiful. I loved the way the rest of the water in the pond hovered. If you compared it to any human release, there was a marked lack of impatience. It simply waited to flow out on its own natural timeline, and the wonderful thing was, the timeline seemed to change on its own to reward the water’s patience: as the channel widened, the water flowed faster…but still never rushed. It is difficult to say why this struck me so strongly at the time, but I thought it was wonderful and lovely.
It was by far the most fun I’ve ever had on a geology trip. I couldn’t get enough of it and I was almost disappointed to head back to camp to pack up. It was a good lesson on how hard it is to control nature; by the time we left, the lake was fighting to rebuild its berm. It was hard to build the channel at first, and then it was hard to control it, and finally it looked like it was impossible to maintain. Sometimes I think engineers fight a losing battle. Nature takes all.