Sunday November 10, 2013 | 08:26 AM
Posted by Harold Johnson

An ancient Greek proverb says: “A man can never cross the same river twice, because both the river and the man are different.”

The same is true of any beach in the world.

On Friday at Curtis Cove, a beach I visit week in/week out all through the year, I saw a sight I’d never seen there before.

What, don’t see it? Look closer.

At the back of the overnight high-tide line, where the highest waves lapped, there lay a long ring of bulges in the sand.

Sand volcanoes.

The sand on a beach’s surface is only the tiniest, most superficial part of a beach’s story. That sand goes down, down, feet or yards -- or more -- underground. And all of those tiny grains don’t interlock perfectly. There’s a lot gaps, a lot of air in that sand. A lot of habitat.

Likewise, the rising tide doesn’t just sit on top of the shoreline -- it floods it throughout, raising the local water table. The waters and waves percolate through those sand grains -- pushing out all of the air.

Usually the air escapes the sand pretty easily, staying ahead of the rising tide, bursting upward and rejoining the atmosphere.

But sometimes the top of the sand gets blocked. It may be mildly “cemented” by a layer of salt. Or as happened in the dark morning hours Friday, it may cemented by a thin sheen of frost.

Whatever the reason, when air can’t get out, the rising tide pushes & compresses it, til something gives.

That something is the sand as a whole. Pockets of trapped, squeezed air push mounds of sand upward, til finally bursting through.

Those little holes in the sand aren’t from clams or other burrowers. They’re escape tunnels, relief valves. Telling a beautiful story of air, water, sand, gravity, tides, chemistry, physics. All for anyone to see.

And all dashed to bits with the next high tide.

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About the Author

Visiting a Maine beach in March 2010, Harold Johnson was shocked by the ocean-borne debris left by recent storms. He grabbed a garbage bag and a camera, and hasn’t looked back.

Since then he has spent most of his free time studying marine pollution, coastal ecosystems, and the mysteries and science of ocean and shore.

Copyeditor and writer by trade, historian and archaeologist at heart, Johnson’s philosophy is simple: Dig below the surface, travel the currents, make the connections, learn. Then share what you learn. He lives in Saco with his wife and young daughter. Follow on Twitter @FlotsamDiaries.

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