Fall Asleep to The Mysteries Hidden in America's National Parks

Yellowstone National Park receives over four million visitors a year. Almost none of them know that the ground beneath their feet is measurably rising and falling — centimeters per year, tracked by GPS, driven by the migration of magma beneath the largest active volcanic caldera in North America. Between 2004 and 2010, the caldera floor rose by eighteen centimeters. Then it subsided. Then it rose again. The pattern is irregular, not periodic, and its relationship to future eruptions is not fully understood. The caldera is breathing. It has been breathing for hundreds of thousands of years. The monitoring is continuous. The ground is still moving.

Tonight we sit with six mysteries inside national parks you can drive to — phenomena that millions of people visit every year without knowing the science behind them is still unresolved. A full-sized hemlock log that has been floating vertically in Crater Lake for at least 130 years, drifting kilometers per day, maintaining a buoyancy equilibrium that limnologists cannot fully explain. The Devil's Hole pupfish — fewer than 300 individuals of the rarest fish on Earth, living on a rock shelf the size of a dining table in a geothermal pool connected to an unmapped aquifer in the Nevada desert, surviving at population sizes that should have caused genetic collapse tens of thousands of years ago. The cliff dwellings of Mesa Verde, built into sandstone alcoves in the thirteenth century and abandoned within a generation, by people whose descendants are living Pueblo communities — the architecture preserved, the reasons for departure still debated. Carlsbad Caverns, where Lechuguilla Cave has been surveyed for over 240 kilometers and survey teams are still finding new passage every expedition, while hundreds of thousands of bats spiral from the entrance each evening into a cave system whose full extent remains unknown. And the synchronous fireflies of the Great Smoky Mountains — thousands of Photinus carolinus flashing in precise unison, six to eight rapid pulses followed by seconds of total darkness, in a coordination pattern that mathematical models can describe but biology has not fully explained.

The caldera is breathing. The log is floating. The pupfish are swimming. The caves are continuing. The fireflies are flashing and resting and flashing and resting in a rhythm that has been theirs for longer than anyone has been watching. Let the dark interval hold you — the pause between flashes, the rest between pulses, the silence between the light. The next flash will come. It always does. But not yet. Sleep.