Tucked inside a canyon in the northern reaches of Iceland, Europe's most
powerful waterfall pounds down upon the Jökulsá á Fjöllum river
below it. The mighty 54 metre-high Dettifoss falls have been around
for thousands of years, but researchers have just discovered that
the home of this natural wonder was created in a matter of days by
extreme flooding.
A study conducted by geoscientists at the University of
Edinburgh and published in PNAS concludes that that the canyon
inside which Dettifoss was formed by a series of distinct floods that individually
lasted just a few days, and occurred thousands of years apart.
Geochemical analysis was used to work out exactly how long rocks
within a 5km stretch of the canyon had been exposed to the
elements, in order to determine how the landscape had changed over
time. The changes that were identified can be attributed to a
series of extreme floods, which took place 9,000 years ago, 5,000
years ago and 2,000 years ago.
Each of the floods was caused by eruptions from volcanoes
beneath Iceland's largest ice cap. They were so powerful that they
tore up the bedrock and formed the canyon's walls, which are 100
metres in some places. These eruptions also pushed three of
Iceland's waterfalls, including Dettifoss upstream by as much as
2km.
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Speaking about the discovery, Edwin Baynes who led the study
said: "We think of natural environments as being formed over
thousands of years, but sometimes they are shaped very suddenly.
This insight into one of Iceland's magnificent landscapes helps us
better understand these processes, and illustrates their
legacy."
The legacy of these floods in shaping Iceland's landscape is
extraordinary. Three very sudden, very short-lived events left
their mark on the country's dynamic and changing landscape for
multiple millenia.
Source Article from http://www.wired.co.uk/news/archive/2015-02/09/dettifoss-waterfall-canyon http://cdni.wired.co.uk/620x413/d_f/dettifoss-1.jpg
Floods created home to Europe's biggest waterfall 'in days'
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