Tuesday, March 18, 2008

deep river

During today’s tour of Mammoth Cave, the discussion turned to the formation of the caves and where the water sits now. As Hannah and I learned on a trip to the Pink Palace Museum in Memphis a couple of months ago, there was a time when most of North America was covered in a shallow ocean (as I recall, the main exception was the Appalachian Mountains, because the Rockies hadn’t formed yet). The tour guide, Joe, said it’s believed that’s when the cave was formed. There are five (explored) levels to the cave, and our tour descended to the third. The water table sits about 360 feet below ground level; during floods it can rise about fifty feet about that. We got down over 200 feet below the ground, and someone asked if the cave ever floods. After explaining the levels and depths, Joe said, “We have a book we really respect, and it says that the rest of these caves aren’t ever going to flood again.” That was one of my favorite examples of the guides’ blend of humor and frankness. We also saw a cave cricket, and some amazing canyon-shaped passages, and the “flowstone” of “frozen Niagara”, which looked in some ways like a rank of organ pipes cascading to the ground and in others like a fleet of fins of some gorgeous aquatic creature. It was a stunning trip, if exhausting (over four miles of walking up and down, after already being somewhat tired from short nights of sleep). Tomorrow we’ll take the lantern-lit tour.

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