Monday, 25 August 2014
Superfast Erosion in Taiwan Shows Millions of Years Are Not Needed
Water has the ability to form – and destroy - geological features quickly. In 1999 an earthquake blocked the Da'an River in Taiwan. But the waters kept on pounding against the blockage, and by 2008 the river had formed a 25-metre wide gorge.
An article in New Scientist states:
“But it just so happens that the river has to bend through 90 degrees before entering the gorge. That means it flows at right angles to the line of the gorge just above the gorge mouth. This sideways flow makes the river extremely abrasive. In effect, it acts like a sheet of sandpaper, grinding away the upstream wall of the gorge at 17 metres a year. At this rate, the whole gorge will vanish in about 50 years.”
Millions of years are not needed for producing (or destroying) geological features. Two 20th century examples are the volcanoes Parícutin in Mexico and Mount St. Helens in the state of Washington, United States.
Mt. Parícutin began as a small fissure in a field in 1943, and reached the height of 336 metres (1,102 feet) within a year.
After Mount St. Helens erupted in May 1980, a single lava flow formed over 7.5 metres (25 feet) of sediment in just three hours.
Just imagine what a year-long global flood with plenty of water could do.
Coghlan, Andy. 2014. Vanishing river gorge shows geology in fast forward. New Scientist (17 August).