Ancient Earth Flood Created Martian-Like Landscape, Researchers Find
Posted: July 12, 2010 at 1:04 am, Last Updated: July 12, 2010 at 8:08 am
Deep in a valley in southeastern Iceland in 2008, Mason hydrologist Sheryl Beach, her PhD student Douglas Howard and a small research team including Georgetown University geomorphology professor Tim Beach were searching.
Hiking over miles of hardened lava that makes up the lunar-like landscape, the researchers examined rocks, water, sand and volcanic ash, all evidence of a mega flood of Biblical proportions — a phenomenon so powerful it can change the face of the planet. An associate professor of geography and geoinformation science, Beach looks at the history of landscapes and how the Earth changes over time.
Dettifoss Falls and downstream river channel of Jökulsá á
Fjöllum, Iceland. Video courtesy of Sheryl Beach, Douglas
Howard and Tim Beach
On that trip to Iceland two summers ago, she and her research team were looking at a jökulhlaup, a catastrophic release of glacial floodwaters. It appears that this particular mega flood dated back to more than 8,000 years.
This phenomenon happens when activity from a volcano heats up glaciers on top of mountains and melts them, causing a huge, powerful flood similar to the volcanic outburst in early 2010 that disrupted air travel around the world.
The team, supported by a grant from the National Science Foundation, had two objectives in Iceland.
One was to look for evidence of a mega flood — a flood of catastrophic proportions that is usually more powerful than it is large in volume — and to model that flood to determine its power and volume.
The other was to compare the landscape features shaped by the flood to similar watershed basins on the planet Mars.
Their results were more than any of them could have hoped for.
Howard, MS Earth Systems Science ’07 and PhD Earth Systems and Geoinformation Science ’09, developed a hydrologic model that calculated the areal extent and the peak discharge of the flood.
With this model, he was able to reconstruct the event and calculate how deep the channel was and how fast the water was going when the catastrophic outburst occurred 8,000 years ago.
“In following the footsteps of other researchers who have looked at this channel, we discovered through our field work that there had been a much greater flood than people had calculated before,” says Beach.
In fact, their evidence suggests this was the largest mega flood of this type on Earth.
“The sheer power of this flood makes it the largest we’ve ever seen,” says Howard. “It may not be the largest spatially, but it is the most forceful.”
Glacial outburst floods, as opposed to river floods, are much more powerful and destructive to the landscape, Beach says.
“The cutting power of a glacial flood is like a bulldozer. It takes rocks with it, plows through the sides of mountains and picks material up and deposits it in a particular way,” says Beach.
Glacial ice makes a U-shaped valley, like Yosemite Valley in California, as it flows.
River valleys are often V-shaped because a river cuts them down more vertically, over time, and then deposits the materials in a well-sorted, orderly manner.
In the case of the Jokulsá á Fjöllum river channel in Iceland, Beach and the team found well-sorted rocks on top of a hill that didn’t match the hill. They matched an area across the channel that had been gouged out.
“It looked like someone had taken a gigantic fire hose, blasted the side of the mountain, flipped its rocks across the channel and sorted them out on the other side. We said to ourselves, ‘That’s what a mega flood looks like.’”
For planetary geologist Howard, these phenomena on Earth can be used to compare similar landscape features on Mars.
Howard, who is now a postdoctoral fellow at the University of Tennessee, has used this jökulhlaup as an “Earth analog” to compare it to Aram Chaos outburst channel, a specific river channel that outflowed from the Aram Chaos crater on Mars.
The channel looked like a former river valley that had flooded, but the features of the landscape called for a much larger source of water than there appeared to be.
By applying his model, and changing it slightly to account for the different level of gravity, Howard was able to prove that groundwater likely contributed to the surface water source.
“There’s very little vegetation in Iceland, and the landscape is quite similar to Mars — though fluvial geomorphological features on Mars are much larger,” says Howard.
“Still, this is possibly the best analog to apply to Mars, and we’ve found spectacular results with our models.”
Howard has traveled to Montana, Idaho, Oregon and Washington to model other floods.
This summer, he will continue the work he started at Mason by traveling to Siberia to study a series of mega floods that happened between 45,000 and 13,000 years ago.
“It’s really fascinating and gratifying to be able to apply our knowledge of our own planet to other planets,” says Howard. “It just brings us one step closer to understanding more about the universe.”
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