Cambrian Explosion: Great Unconformity (Introduction)

by David Turell , Monday, August 23, 2021, 19:44 (1188 days ago) @ David Turell

Now thought to be due to previous great continents tearing apart:

https://www.sciencedaily.com/releases/2021/08/210819195030.htm

"'The Great Unconformity is one of the first well-documented geologic features in North America," Peak said. "But until recently, we didn't have a lot of constraints on when or how it occurred."

"Now, she and her colleagues think they may be narrowing in on an answer in a paper published this month in the journal Geology. The team reports that a series of small yet violent faulting events may have rocked the region during the breakup of an ancient supercontinent called Rodinia. The resulting havoc likely tore up the earth around the canyon, causing rocks and sediment to wash away and into the ocean.

***

"Roughly 700 million years ago, basement rock in the west seems to have risen to the surface. In the eastern half, however, that same stone was under kilometers of sediment.

"The difference likely came down to the breakup of Rodinia, a gigantic land mass that began to pull apart at about the same time, Peak said. The researchers results suggest that this major upheaval may have torn at the eastern and western halves of the Grand Canyon in different ways and at slightly different times -- producing the Great Unconformity in the process."

Comment: That gets rid of the previous rather lame theory: erosion