Where did all the stones come from?
Geologists have this issue quite wrapped up, except for some missing layers or unconformities that have been completely eroded away. Again, there were a number of forces at work, and this is where continental drift vulcanism and climate change come into play.
The fact that Earth's continents are not fixed in place, but rather floating in a sea of molten rock, meaning that they move very little, relatively speaking. The face of the Earth is composed of a dozen of these "panels" that make up the crust. Seven of these plates are very large and consists of whole continents and ocean floors and the rest are small in comparison. Plates average being about 50 miles or 80 kilometer thick and float on the Earth's mantle. The record, which includes the Grand Canyon, the North American plate was once considerably further south than its current location and therefore had a very different climate. As time has gradually moved north and rotated about ninety degrees to its current location and configuration.
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