Eratics: Boulders scattered around the Scabland that do not match the rock types found in those areas.
Glaciers move down from Canada scraping and reforming the landforms.
Hanging Valleys: glaciers enter valleys and enlarge them.
Problem: Glaciers didn't reach Scabland!
Then ripples were discovered.
J Harlen Bretz challenged the view that most landforms had formed over long periods of time by saying a megaflood changed the landscape nearly over night. 900 ft deep..a body of water raging through the scabland making its way to the pacific. People dismissed his theory.
Where did the water come from?!
JT Pardee
Missoula Montana. Epic confrontation between water and ice.
Scratches on rock show glacial migration.
Glacier created a lake by damming a river.
Glacial Lake Missoula. 250 miles away.
Joesph T. Pardee- knew about the lake. But had no proof of where it had gone.
He found ripples that indicated a movement of the huge body of water that pointed towards the scablands.
What caused the lake to empty?
Proof found on Iceland. Matthew Roberts work..ice dams.
1996 huge body of water flowed through southern Iceland.
At the base of the ice dam the pressure of the area prevents ice from freezing/expanding. Super cooled ice.
Super cooled water trickles through the cracks in the ice which creates friction that releases heat.
The water moves through the glaciers and melts the ice.
Responsible for the collapse of the ice dam at Glacial Lake Missoula
2.5 Trillion tons of water surging across American northwest.
The pressure of the water in the tunneled ice dam becomes too much and it collapses creating a hole that water pours out of.
Dry Falls. How could water create that!? It's normally carved out by glaciers.
And potholes? How did water create that?
Scale independent. They did a model experiment and it looks just like the real ones!
Massive amounts of water can carve out these craters and make it look like years of erosion.
What about the potholes?
The put a hard object in a flow of water and turned the speed of the water up.
Bubble streams. The bubbles collapse against the object creating a sledgehammer effect.
So can bubbles gouge holes in solid rocks like those in the scabland?!
YES!
Underwater vortex/tornado of bubbles carving out rocks.
Boulders were flung everywhere.
1980, Bretz got Penrose Medal!
There may have been more than one gigantic flood!
Big canyon with many layered deposits shows ash from Mt. St. Helen.
Ash fell into water and drifted into layer? Not likely for this amazing clear line.
This suggests that there may have been many gigantic floods!
Dating the sediment takes time.
The top and bottom layers are 20,000 years apart!
:o!
Floods were regular on the scablands during the Ice Age!
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| Scablands |
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| Scablands (along Highway 90) |
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