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1.75 Billion Years Ago “Early Proterozoic” Island Arcs added to North American Craton Once 15 miles below the surface of the earth! Vishnu Schist and Zoroaster Granite. Angular Unconformity. The Great Unconformity. 525 mya. 525 mya. 740-1255 mya. 1750 mya. The Great Nonconformity.
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1.75 Billion Years Ago“Early Proterozoic”Island Arcs added to North American CratonOnce 15 miles below the surface of the earth! Vishnu Schist and Zoroaster Granite
Angular Unconformity The Great Unconformity 525 mya 525 mya 740-1255 mya 1750 mya
Grand Canyon carving Pangea Pre and Post Rodinia Atlantic rifting
Vee Diagram of Inquiry from D. B. Gowin Focus Question Thinking Doing Principles Claims Concepts Records Events and Objects (Prior Knowledge) (New Knowledge))
When did the Colorado River begin to carve the Grand Canyon? (Focus Question)
How did the San Andreas fault help the Colorado River leave the Colorado Plateau?
Implications of the Miocene(?) Crooked Ridge River of Northern Arizona for the Evolution of the Colorado River and Grand Canyon Ivo Lucchitta (New Knowledge Claims)
Origin and Evolution of the Colorado River System Karl E. Karlstrom (New Knowledge Claims)
The mystery of the pre–Grand Canyon Colorado River—Results from the Muddy Creek FormationJoel L. Pederson (New Knowledge Claims)
Age of the Grand Canyon: 80 million or 6 millions years? 80 mya ago the Cretaceous seas withdrew. Rivers drained to the Northeast for 50 million years. Laramide orogeny uplifted the Colorado Plateau— North American crumpled and the Farallon Plate subducted shallowly from 70 to 40 mya. Rivers “disappear” from view on the Colorado Plateau between 30 and 16 mya (Principles and Prior Knowledge)