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On a Possible Giant Impact Origin for the Colorado Plateau

It is proposed and substantiated that an extraterrestrial object of the approximate size and mass of Planet Mars, impacting the Earth in grazing incidence along an approximately N-NE to S-SW route with respect to the current orientation of the North America continent, at about 750 million years ago (750 Ma), is likely to be the direct cause of a chain of events which led to the rifting of the Rodinia supercontinent and the severing of the foundation of the Colorado Plateau from its surrounding craton. It is further argued that the impactor was most likely a rogue exoplanet, which originated from one of the past crossings of our Solar System through the Galactic spiral arms, during the Sun's orbital motion around the center of the Milky Way Galaxy. New advances in galactic dynamics have shown that the sites of galactic spiral arms are locations of density-wave collisionless shocks. The perturbations from such shocks are known to lead to the formation of massive stars, which evolve quickly and die as supernovae. The blastwaves from supernova explosions, in addition to the spiral-arm collisionless shocks themselves, could perturb the orbits of the streaming disk matter, occasionally producing rogue exoplanets that can reach the inner confines of our Solar System. The similarity of the period of spiral-arm crossings of our Solar System, with the approximate period of major extinction events in the Phanerozoic Eon of the Earth's history, as well as with the (half) period of the supercontinent cycle, indicates that the global environment of the Milky Way Galaxy may have played a major role in initiating Earth's tectonic activities.