It's
true! Good homework! That's why all those crazy carved out drainages and draws in eastern WA with no river in them. Here in Mizzu and areas around here, there are horizontal lines in the bare hills which really show up with low sun or just a dusting of snow - they are the many
shorelines of Glacial Lake Missoula! They look like topo lines or bathtub rings in real time. Imagine, 10 or 20,000 years later, they're still there. And the water level was 2000 feet above us, multiplied by the area of all the western valleys - it's mind-boggling. It broke and flooded and refilled every couple of thousand years.
Mike's Geology Lesson #1: (I've probably duplicated many of your photos)
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This is over in Idaho - same thing. Uncovered after a fire.
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Then in places like this - Camas Prairie Montana - there are enormous ripples on the landscape. These are like the ripples in the sand under a stream, on a colossal scale.
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In Washington
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On the left is carved out rock. On the right is the last of the soil as it washed away.
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Here are the many lake bottoms in the soil near Walla Walla....
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Then all this was carved out of solid rock - the bedrock below the soil - and carved out the Columbia River Gorge to the ocean.
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Full disclosure - my neighbor the late great Dave Ault wrote the book, and my father was a geologist.
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