December 19, 2013 | David F. Coppedge

Geologists Warming Up to Catastrophic Floods

Megafloods larger than anything seen today are better concepts for explaining certain features on Earth and Mars. and Live Science reported that megaflood theory is helping explain a large canyon in solid basalt in Idaho.  Niagara Falls is a classic amphitheater-shaped canyon retreating upriver under the onslaught of water.  The amphitheater-shaped heads of Malad Gorge in Idaho suggest very rapid, catastrophic cutting through the rock by “truly extraordinary” floods.  Caltech researchers publishing in PNAS believe the flood that formed Woody Cove and Stubby Canyon simultaneously, with walls 165 feet high, was huge:  at least 30 feet deep, flowing at 330,000 gallons per second.  (A V-shaped canyon in the system, they believe, took tens of thousands of years to form.)  What they are learning can inform interpretations of other structures not only on Earth:

These insights into ancient megafloods on Earth could, in turn, tells scientists what may have occurred on the surface of Mars millions of years ago.

Mars also has amphitheater-shaped canyons in abundance (for a reverse view of how a Mars flood may help explain Earth features, see 6/28/13).  Andrew Lamb of Caltech cautions that other agents than megafloods of water could have formed them, but feels the openness to catastrophic explanations makes this an exciting time to be a geologist.  “As geologists, we are always seeking new insight to read this record to better understand our planet and its potential for change.

Undersea Grand:  Speaking of large canyons, there’s one that rivals the Grand Canyon, but it’s underwater.  Off the coast of Morocco, Agadir Canyon is half a kilometer deep, up to 20 miles wide and 280 miles long.  It has just been mapped by a German vessel, Live Science reported, after a five-week mission.  Live Science also posted a 6-image gallery including the map and pictures of some of the life forms found down there.  “There are a lot of interesting features that no one has ever gone and looked at,” the article said; but it misstated current rapid origin theories for the Grand Canyon, saying, “Long flows of sediment carved out the canyon over millions of years, much like a river carves out a canyon, including the Grand Canyon, on land.”  There’s no reason, though, that sediment flows could not also be massive and rapid like megafloods.

Andrew Lamb’s insight may not go far enough, but it’s a start.  We remind readers that it is odd to look for megafloods on Mars, a cold and dry world, while discounting the work of megafloods on Earth that has water covering 70% of its surface.  Remember that J Harlan Bretz’s megaflood theory for the Channeled Scablands of Washington was ridiculed for decades before it became the accepted paradigm (4/30/09).  It’s not the amount of time, but the volume of water, that can make a profound difference.


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