Friday, November 7, 2014

Water: Sculptor of the Earth

While plate tectonics rearranges the Continents, lifts mountain ranges and ignites volcanism, water sculpts the surface of Planet Earth.  Falling as rain, snow or ice pellets and lashing the coastlines as waves, this vital substance erodes and shapes our landscapes.

Whether moving as liquid water in rivers and streams or as solid ice in glaciers, water sculpts the mountains, plateaus and mesas of our planet, carving cirques, canyons and valleys and then spreading that debris across the lowlands or delivering it to lakes and oceans.  Along the margins of the Continents, wind-driven waves mold the shorelines, producing cliffs, sea stacks and barrier islands.

Of course, vegetation modifies this erosion in many regions, stabilizing soil and dunes, slowing and filtering the flow of streams and absorbing excess precipitation.  Unfortunately, we humans have a history of destroying that protection by draining wetlands, clearing forests and plowing prairies, augmenting the risk of destructive floods.