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Imagine an entire planet where the universe's finest liqueur is boiled out of fermenting seas by a brilliant yellow star, distilled in the skies and rained back down on the land, forming lakes and rivers of the inebriating brew. The planet, of course, is Earth, and the liqueur is freshwater.
Without freshwater Earth's land masses would be barren, the continents might be in different locations, mountains would be far taller, and life virtually impossible. Earth's very character and appearance are the result of the planet being fairly drunk on this precious grog.
Liquid Destroyer
Luckily for us land animals, Earth can't help but make freshwater. It happens when the sun heats and evaporates water from the oceans. The salts and other minerals are left behind, creating pure water vapor in the air. As it is carried higher to cooler air, it condenses and makes clouds, which can produce rain or snow when forced higher over land.
That's the water cycle, of course. It's something taught to every schoolchild — for good reason. Not only does the water cycle give us the water we drink and use to grow food, it is also the carver of coastlines, sculptor of mountains and the burier of seas. It might even play a critical role in plate tectonics, the process that keeps creating and destroying crustal plates that make up the surface of the planet.
One of the more dramatic examples of what a few gazillon raindrops and snowflakes of freshwater can do over time is the Grand Canyon. Over the past 5 million years, the Colorado River has just as steadily cut its way through the constantly bulging Colorado Plateau, making the mile-deep, 18-mile-wide, 200-mile-long Grand Canyon along the way.
By moving such gigantic masses of rock from one place to another, freshwater also removes weight from the Earth's crust in one place and weighs down others. By wearing away rocks of the Himalaya, for instance, rain and snow make the mountains lighter and actually speed up the rate at which the range buoys upward on the more plastic layer below the crust — the zone called the mantle.
In turn, by affecting the pressure in the mantle, it's thought by some geophysicists that currents can be generated in the mantle that influence how, when and where tectonic plates move. This top-down theory to what drives plate tectonics makes freshwater a central player in the making of every inch of Earth's surface today.
