Enormous volumes of floodwater from the Missoula megafloods once poured over Dry Falls, which stretches 3.5 miles wide and drops 400 feet to a plunge pool now fed by groundwater.
Photo: Tamara Pico
Towering cliffs carved by the Missoula megafloods are found throughout the Channeled Scablands in eastern Washington.
Photo by Tamara Pico
Geologists led by Tamara Pico, assistant professor of Earth and planetary sciences at University of California, Santa Cruz, have explained how the formation known as the Channeled Scablands, Washington, were formed in a series of cataclysmic floods called the Missoula megafloods. Although these were massive, nevertheless they were local to what is now Eastern Washington.
YECs often point excitedly at the effects of this water erosion as evidence of a global flood, just as they claim the Grand Canyon is, being too parochial to distinguish between a part of the USA and the entire planet. But the scientists have shown how this carving of long, deep channels and towering cliffs was caused by the changing weight of the ice sheets as they retreated at the end of the last Ice Age, causing the entire landscape to tilt and so changing the course of the megafloods.
As the UC Santa Cruz news release explains:
People have been looking at high water marks and trying to reconstruct the size of these floods, but all of the estimates are based on looking at the present-day topography. This paper shows that the ice age topography would have been different over broad scales due to the deformation of Earth’s crust by the weight of the ice sheets.
We used flood models to predict the velocity of the water and the erosional power in each channel, and compared that to what would be needed to erode basalt, the type of rock on that landscape.
As the landscape tilted, it affected both where the water overflowed out of Lake Columbia and how water flowed in the channels, but the most important effect was on the spillover into those two tracts. What’s intriguing is that the topography isn’t static, so we can’t just look at the topography of today to reconstruct the past.
When you are there in person, it’s crazy to think about the scale of the floods needed to carve those canyons, which are now dry. There are also huge dry waterfalls—it’s a very striking landscape.
Scientists were not the first people to look at this. People may even have been there to witness these floods.
We used flood models to predict the velocity of the water and the erosional power in each channel, and compared that to what would be needed to erode basalt, the type of rock on that landscape.
As the landscape tilted, it affected both where the water overflowed out of Lake Columbia and how water flowed in the channels, but the most important effect was on the spillover into those two tracts. What’s intriguing is that the topography isn’t static, so we can’t just look at the topography of today to reconstruct the past.
When you are there in person, it’s crazy to think about the scale of the floods needed to carve those canyons, which are now dry. There are also huge dry waterfalls—it’s a very striking landscape.
Scientists were not the first people to look at this. People may even have been there to witness these floods.
Professor Tamara Pico, Lead author
Assistant professor of Earth and planetary sciences
University of California, Santa Cruz, CA, USA “
Assistant professor of Earth and planetary sciences
University of California, Santa Cruz, CA, USA “
As ice sheets began melting at the end of the last ice age, a series of cataclysmic floods called the Missoula megafloods scoured the landscape of eastern Washington, carving long, deep channels and towering cliffs through an area now known as the Channeled Scablands. They were among the largest known floods in Earth’s history, and geologists struggling to reconstruct them have now identified a crucial factor governing their flows.Not only does the YEC mythology not have a sufficient timescale to incorporate the geological changes needed to explain these formations, but it doesn't even recognise the possible mechanism in terms of Ice Ages, retreating ice sheets and ice dams, which is why, to their simplistic way of thinking, the only explanation for the geology must be magic. However, with the longer term perspectives provided by science, the mechanisms not only become amenable to reason but the explanation covers all the observable data.
In a study published February 14 in Proceedings of the National Academy of Sciences, researchers showed how the changing weight of the ice sheets would have caused the entire landscape to tilt, changing the course of the megafloods.
During the height of the last ice age, vast ice sheets covered much of North America. They began to melt after about 20,000 years ago, and the Missoula megafloods occurred between 18,000 and 15,500 years ago. Pico’s team studied how the changing weight of the ice sheets during this period would have tilted the topography of eastern Washington, changing how much water would flow into different channels during the floods.
Glacial outburst floods
Glacial Lake Missoula formed in western Montana when a lobe of the Cordilleran ice sheet dammed the Clark Fork valley in the Idaho panhandle and melt water built up behind the dam. Eventually the water got so deep that the ice dam began to float, resulting in a glacial outburst flood. After enough water had been released, the ice dam resettled and the lake refilled. This process is thought to have been repeated dozens of times over a period of several thousand years.
Downstream from glacial Lake Missoula, the Columbia River was dammed by another ice lobe, forming glacial Lake Columbia. When Lake Missoula’s outburst floods poured into Lake Columbia, the water spilled over to the south onto the eastern Washington plateau, eroding the landscape and creating the Channeled Scablands.The landforms on the Columbia Plateau in eastern Washington reveal a past punctuated by violent floods.
Credit: NASA Earth Observatory
During this period, the deformation of the Earth’s crust in response to the growing and shrinking of ice sheets would have changed the elevation of the topography by hundreds of meters, Pico said. Her team incorporated these changes into flood models to investigate how the tilting of the landscape would have changed the routing of the megafloods and their erosional power in different channels.
But then, why would any sane person expect a Bronze Age Middle Eastern origin myth to explain the geology in part of North America, when the authors had no inkling that such a place even existed or was once covered by vast ice sheets hundreds of feet thick? And yet adults in backward parts of the world still teach their unfortunate children to treat those myths as real science and history and not to dare even question them, no matter how poorly they equate to the real world.
In doing so, they deprive them of the pleasure of finding things out and understanding the truth about the planet we have the good fortune to inhabit. As such, that amounts to child abuse and pedagogy of the worst kind.
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