Nova: Mystery of the Megaflood

     Last week during lab time we watched the PBS documentary on the Megaflood. The Megaflood took place during the last ice age in Washington state. Scientists consider this 'Megaflood' to be one of the most perplexing geologic mysteries. In the Scablands there are large granite boulders that are not native to the area and large pot holes.

     One of the first predictions on the cause of the strange topography of the scablands was gradual river erosion. Scientists asked the question: How could a river create these features? The only river close enough to the Scablands is the Columbia River. However, no river can form pot holes or carry large boulders. There was also no proof that the Columbia River ran through the Scablands. 

     The next theory to come along was ice and glaciers. Scientists believed that the only force that could have placed the boulder in the area was ice. Ice would have carved through rock to build mountains. Glaciers would have worked over 1,000 years to create the strange land formations. The theory of ice was improving, but there was no proof that glaciers actually reached the Scablands. 

     The final theory to come along took a long time to prove and be accepted by scientists. A man named Jay Harlen Bertz researched and came to believe that the Scablands were not a result of gradual erosion, but rather a significant event that happened overnight. Bertz believed that a massive flood created the Scablands. At first, Bertz's theory was shut down and turned away. One of the main questions scientists asked were where did the water come from? Bertz had the research and answer to their question.

     Bertz had evidence that water had been in the Scablands at one point. The rippling action of water is present in the ground proving that water had been in the area. The ripples range from 20-40 feet. The water that came into the area was from Missuola (250 miles east of the Scablands). A glacier created a lake by damming the river. Scientists refer to the lake as 'Glacier Lake Missoula.' River water built up behind the dam. Eventually the weight of the water was too much to bear for the glacier and it exploded. The 'Megaflood' carved valleys and canyons in the Scablands. Glacier pieces went flying with the pressure, carrying boulders and randomly dropped them in the Scablands. Underwater tornados created the massive pot holes. The water from behind the dam would have been traveling 60 miles per hour towards the Scablands. It would only have taken a few hours to reach the Scablands. 

     Today, scientists believe that there may have been more than one giant flood. The KT Boundary has multiple layers that hold evidence of a flood, an ash layer (Mt. St. Helen's would have erupted at about the same as the Megaflood), and another flood. There is a 20,000 year difference between the first and third layer of floods. The Megaflood is something that will always intrigue the field of science. The fact is that the truth probably lays in between many theories.
Below are pictures of the Scablands today: