The Fastest Natural Erosion on Earth

A natural gorge in Taiwan is eroding at an exceptionally fast rate, showing what would traditionally be a thousand-year erosive process in mere decades. Researchers taking a close look at this natural phenomenon are calling it "downstream sweep erosion."

According to a study recently published in the journal Nature Geoscience, the gorge formed after an earthquake in 1999 lifted a massive amount of earth for more than half-a-mile (1 km) and effectively cut off the Daan river.

"In terms of river erosion, the Daan river gorge in Taiwan is extremely rare," Kristen Cook at the German Research Centre for Geosciences in Potsdam, told NewScientist.

According to Cook, the unusual gorge actually forces the river to bend a full 90 degrees. The Daan then literally rides the wall of the gorge, looking like a whiplash waterslide fit for giants. Of course, this sideways flow is extremely abrasive, carrying sediment and small pebbles along for the ride.

Like an endless belt of sandpaper, the Daan erodes the gorge's upstream wall at a rate of nearly 56 feet (17 meters) a year. Cook suggests in her study that the gorge will be nothing but wet sand within the next 50 years.

"As the upstream boundary of the gorge keeps moving downstream, the gorge will get shorter and shorter until the upstream boundary reaches the exit of the gorge, and the whole thing is gone," she explained.

What will be left? A wide floodplain consisting of fine sediment and a smooth base of very polished stone.

This is one of the few rare occurrences where geologists are given an opportunity to witness the full natural erosion of a geological formation as large as the gorge from start to finish.

Cook says she plans to not waste this opportunity, and will be monitoring and studying it in great detail alongside her excited colleagues for years to come.