Paleontology and geologyAn episode of mountain building (the Nevadan Orogeny) occurred in southwestern Arizona during the Jurassic. The mountain building and associated volcanism dumped huge amounts of sediment into low-lying areas to the north. Most of northern Arizona was an interior lowland during the Jurassic, variously dominated by rivers and wind-sculpted landscapes with spectacular dune fields. This map indicates the presence of Jurassic rocks scattered throughout the higher elevations in the state. |