Wednesday, December 3, 2008

Cumberland Island

The sea is always coming and going. Twice a day the tide goes in and out. Every few million years, the coastlines are shifted miles in and out. If you've ever seen a monthly tide chart, or a line graph of transgressions and regressions through geologic time, the images are strikingly similar. One of the great convergences of these two periodic ocean pulses are Georgia Barrier Islands. Long-term sea-level changes make barrier islands possible while Oceans get bigger. The moon-coupled short-term tide ebb and flow make the salt marsh possible. The salt marsh makes Captain D's possible.

The picture here shows the result of tide pulses acting on sediments every day between the islands and the land, away from waves. This is what it looks like at low altitude from a small plane full of friends. A whole load of marine organisms uses this cushy zone for raising tender young that grow up to be your tender fish sticks and popcorn shrimp. Sam eats shrimp and blue crab. He also thinks barrier islands and marsh are good offspring-raising grounds for humans.

That's why we know about things like tide and have the sense to ask about historic sea level at the largest scales. Because there are some people who are willing to be in, and become part of, a place. To watch its rhythms, to appreciate its beauty and its part of the story. By lightly populating the right spots on Earth with watchful people, and connecting them to a network of askers and listeners, we can almost hear the planet breathe. Tide charts begin to look like EKGs, seasons wiggle the toes, sunrises and sunsets blink and see.

It's a big rock. Somebody's gotta watch it.


  1. "Meanwhile, the sea ebbs and flows in these grander tides of earth, whose stages are measurable not in hours but in millennia - tides so vast they are invisible and uncomprehended by the senses of man. Their ultimate cause, should it ever be discovered, may be found to be deep within the fiery center of the earth, or it may lie somewhere in the dark spaces of the universe." -Rachel Carson

  2. But if rivers come into being and perish and if the same parts of the earth are not always moist, the sea also must necessarily change correspondingly. And if in places the sea recedes while in others it encroaches, then evidently the same parts of the earth as a whole are not always sea, nor always mainland, but in process of time all change. - Aristotle, 335 BC

  3. I'd love to see the pictures from your world tour. I'm sure that there are good stories to be had. If you are in Chattanooga during the holidays drop me an email and we can get some something to eat somewhere.

  4. The Silurian bimodalvolcanic system of coastal Maine is also grounds for good human offspring-raising! Come visit!