Dettifoss, a Creation of the Land of Fire and Ice

December 26, 2018

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December 2018 Viewer's Choice

Photographer: Patti Weeks 
Summary Author: Patti Weeks 

Aptly referred to as the Land of Fire and Ice, the island of Iceland was born of volcanic eruptions over millions of years and was buried under ice until about 8,000 years ago. Seeing waterfalls is one of the highlights of an excursion to Iceland.

Featured above is Dettifoss, the largest of three waterfalls along the Jökulsá á Fjöllum river, which flows out of Iceland’s Vatnajökull National Park. The river stretches 128 mi (206 km) from its source, the 3,000 sq mi glacier Vatnajökull, Europe’s largest glacier, to the Greenland Sea. Dettifoss (loosely translated as “the collapsing waterfall”) is the most powerful waterfall in Europe, spilling an average of 96,500 gallons per second over its drop of 144 ft (44 m). This volume of water creates a thundering noise, heard far in advance of seeing the falls, and an enormous crashing spray that rises to the top of the falls and can be visible for several miles.

Dettifoss plunges into the Jökulsárgljúfur canyon, a chasm nearly 16 mi (24 km) long and as deep as 328 ft (100 m). From recent studies, geologists theorize that the canyon and waterfall were likely formed by major volcanic eruptions associated with the Vatnajökull glacier, which is situated atop 8 subglacial volcanoes, and subsequent jökulhlaups (catastrophic glacial floods) over the past 9,000 years. These eruptions released rapid and enormous volumes of meltwater along the river, dislodging large chunks of previously existing columnar basalt. The sudden changes in elevation, called knickpoints, are where the waterfalls formed. Glacial megafloods can release up to 3.25 million liters of water, 6 times more than a normal flood. Geologists also postulate that certain existing knickpoints have been shifted rapidly upstream as the result of violent and extreme outburst flooding.

These photos, taken September 8, 2018, were shot from the west bank, the most accessible side of the river. The people in the second photo, seen near the guardrail-less edge of Dettifoss’ sheer drop on the east bank, are warned of the slippery rocks but have the closest view of the 328 ft (100 m) wide waterfall. Readers may recognize Dettifoss from the opening scene in the 2012 feature film “Prometheus.”

Photo Details: SONY DSC-HX400V camera; 4.3 mm focal length; 1/320 second exposure; f/3.2 aperture; ISO 80. Second photo 37.9 mm focal length; 1/250 second exposure; f/5 aperture; ISO 125.