About 15,000 years ago , as the latest ice old age was winding to a close , glacier that cover Canada began to disappear . Then , one 24-hour interval , those shrinking glaciers unleashed the waters of a lake the sizing of Lake Huron , which scoured the estate from Montana to the Pacific coast . Here ’s what we get it on of the great Ice Age flood .
Over at Ars Technica , Scott K. Johnsonhas an unbelievable , in - deepness clause about his trip to impose the site of this flood , known as the Scablands . Thousands of years ago , a rampart of H2O bashed its way through mess ridge , turn portion of Idaho into jumbo , irregular lakes , and left hills of shattered rock debris behind . Unlike other historic floods of similar intensity , this one happen through canyons lined with volcanic basalt rock that had cooled into geometric columns .
Photo of the basalt editorial , by Scott K. Johnson
As it smashed through , the pee tore these huge column from drop faces and propelled them along with the flood . As a solvent , we ’re left with an eerie geologic record of the water system ’s itinerary , paved with smashed stone columns .
As Johnson retraces the route of the flood , he tells us about the controversial history of the flood lamp ’s discovery by rogue geologist J. Harlen Bretz — and shows us why alluvion are among the Earth ’s most terrifying catastrophe .
His tale begins :
Traveling from the verdant , stodgy coastal belt of the Pacific Northwest , one could be forgiven for feeling that the specify equipment characteristic of Eastern Washington is its dryness . It ’s a land apparently thirst of rainwater in the shadow of the Cascade Mountains . But the teetotal landscape painting get it on as the “ Scablands ” actually tells a story about redundant — surplusage of water , water that was torrential and sudden .
The Scablands are basically lesion , still unhealed by sentence and wearing . They snub through the kingdom and down into the rock after a serial of unfathomably large floods loose by the catastrophic draining of great wintry lakes — half the volume of Lake Michigan splashed onto the land in less than a week . If you could imagine that , you ’ve got us tick . The write up recorded in this landscape is so incredible , it took one geologist decennium to win over his colleague that he was record it right …
By chance , I began my trip in the very place that captured the interest of a young J Harlen Bretz when he got his hands on that novel USGS mapping — Potholes Coulee . I was welcome to the Scablands almost immediately by a rattler eager to verify I bang which spot of shade it was currently enjoy — a admonisher that , despite the geological spread for the center around me , I should also observe my pace .
I walked toward the Columbia River , flank by column of basalt , now and again dropping over considerable ledges that were once waterfalls . feed by overflow from agricultural irrigation , some hosted trickle of water once again .
Like most substances , lava contract as it cool down . A flow of lava that is many mile wide can shrink a bit vertically without complications , but contracting horizontally is another story . So as the rock-and-roll cools , it break into about hexagonal columns ( plus or minus a side ) , as at illustrious locations likeDevil ’s Toweror theGiant ’s Causeway . Not only are these columns visually sympathetic , they ’re key to the dramatic landscape of the Scablands .
current cut up V - shaped valleys through mound , with a lean ribbon of flow water cut downward like a knife . As the walls get onto into the pass of the current channel , the vale widens but maintains that “ quint ” shape . When it make flatlands , the current slow and meander , carving a wide , soft deluge homely as it wiggles back and off over time .
But these coulees are n’t like either of those ; they ’re sudden and sharply fix , with bland bottoms and erect cliffs for sides . No stream lift down their length , and the floor is a jagged mess . They attend more like scar left by the talon of a world - eating dragon than the workplace of some belittled , if unremitting , stream .
You must scan the entire storyover at Ars Technica
Also , this video may help you visualize just how the flood start out , and how it howl through three states — Montana , Idaho , and Washington — before reaching the ocean .
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