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.
