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Catastrophic floods on Mars carved some of the planet's deepest valleys
- JoeAltmaier 5y agoCatastrophic floods on the Earth carved some impressive valleys. The North American Mississippi Valley varies from a mile wide between bluffs in the north to many miles wide downstream. It was apparently carved after the last glacial melt, when the remaining ice in Canada gave way. The ice was still a mile or two thick, and melted in pockets (i.e. enormous fresh-water lakes thousands of feet deep and many miles wide). When the ice dams holding these lakes broke one summer, it released a burst of water a half-mile high. That ground everything in it's path into powder and scoured the earth down to the bedrock, as it spent the summer surging through the US midwest and down to the sea. I imagine some poor tribe looking up and seeing what looked like an enormous storm front from the north. Only to discover it was a large brown bow wave thousands of feet high, roiling with the destroyed forests and prairies it had uprooted, churning toward them at 30-40MPH. Inescapable and inevitably fatal, I wonder if they ever understood what hit them.