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Thu Jan 3, 2019, 09:18 AM

Around the world, miles of rock are missing. Could 'Snowball Earth' be the culprit?

When the famed explorer John Wesley Powell bumped, splashed and thrashed his way down the Colorado River in 1869, he discovered one of the most striking geologic features on Earth. Not the Grand Canyon — although that too is a marvel — but a conspicuous boundary between the sunset-colored sediments of the upper walls and the dark, jagged rocks below them.

Powell had learned to read the layers of desert rocks like pages in a book, and he recognized that the boundary represented a missing chapter in Earth’s geological history. Later, researchers realized it was more like an entire lost volume, spanning roughly one-fifth of Earth’s existence, and that a similar gap existed in many places around the world.

“There must have been some sort of special event in Earth’s history that led to widespread erosion,” said Steve Marshak, a geologist at the University of Illinois at Urbana-Champaign who studies what has come to be known as the Great Unconformity.

New research suggests it was something special indeed. Scientists propose that several freak episodes of global glaciation scoured away miles of continental crust, obliterating a billion years of geologic history in the process.


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Reply Around the world, miles of rock are missing. Could 'Snowball Earth' be the culprit? (Original post)
Zorro Jan 2019 OP
Victor_c3 Jan 2019 #1

Response to Zorro (Original post)

Thu Jan 3, 2019, 10:45 AM

1. The timing of this makes me think of the Burges Shale fossils

Apparently, I’m not the only person to think about the correlation of the event discussed in the article and the apparent explosion in the complexity of life at around the same time. The possible explanation of extra nutrients being brought into the oceans because of erosion and the apparent explosion in evolution makes a lot of sense.

As an aside, I find it interesting that more and more evidence keeps appearing that demonstrates that life formed on our planet earlier and earlier. For instance, the appearance of an excess of oxygen dependent minerals at about 3+ billion years ago suggests life might have existed not very long after our planet formed. I wonder what evidence of the evolution of life might have been removed by the glaciation and erosion event discussed in the article. Perhaps soft bodied animals found in the Burgess Shale might have existed much earlier than we believe.

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