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The One-Minute Geographer: This Fragile Earth (10) — The Seashore and the Four Spheres
One of the most exciting places on our Fragile Earth is the seashore. Most people, giving a quick answer to “what’s a seashore?” would say that’s where land and water meet : sea and shore. But wait! There’s more than that going on!
Scientists conceptualize the earth’s surface as the interaction or interface of the four great systems or ‘spheres’ on earth. Lithosphere, hydrosphere, atmosphere and biosphere. Fancy names for land, water, air and lifeforms. Or even more simply, solids liquids, gas and life.
Now go back and think of the seashore. It’s not just land and water, but the continuous interaction of land and water with the atmosphere creating the waves, picking up salt to give us that saltwater smell, bringing in fog, blowing sand into the shape of dunes. And, of course, life. Fish, seagulls, crabs, clams, seaweed, dune grass.
I’ve started with an example of a saltwater beach, but any lake shore or river is also a location where interaction among the four spheres is evident.
Just think of the myriad ways the four spheres interact all over the earth. Pick any two. I’m sure you can add a lot more interactions that go on between any two spheres that come to your mind.
Atmosphere and lithosphere: Dust storms, sand dunes, the rich loess wind-deposited soils of the Midwest and Great Plains. How wind strength and direction are impacted by topography.
Biosphere and atmosphere: Breathe! Plants taking out carbon dioxide and producing oxygen. People adding CO2 and pollution. Birds fly in it. Birds’ nests adapted to resist wind. Trees felled by a storm. The pollen count.
Hydrosphere and biosphere: Have a drink! You won’t survive without one. Fish! Algae, seaweed and every type of marine life. Irrigation. Kids at play at the beach.
Lithosphere and hydrosphere: Every river valley that exists. Glaciation shaping entire landscapes. Floodplains and deltas. Sedimentary rock formations. Landslides and mudslides. Beach erosion and coasts reshaped…
