earthstory:The Great Unconformity in the Grand CanyonWe’re finally here. I’ve literally
earthstory:The Great Unconformity in the Grand CanyonWe’re finally here. I’ve literally spent a couple weeks in a small slice of the Grand Canyon. The basement rocks and the Grand Canyon Supergroup rocks make up a small piece of the Western U.S. They tell hugely important stories of how the continent was assembled, but compared to the units we’re about to see they appear as but a sliver.Everything we’ve seen so far shows up in small areas in the inner gorge. Suddenly in literally 1 plane, everything is going to change and we’re going to look at rocks that outcrop across the entire Western United States.Each of these photos shows the same boundary; generally it is called the Great Unconformity (although that term is also used for Hutton’s unconformity in Scotland). It is so obvious that it was recognized as a major boundary during John Wesley Powell’s first trip through the Canyon in the late 1800’s. Keep reading -- source link
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