OUTLINE • Introduction • Precambrian Earth History • The Paleozoic Geography of Earth • Paleozoic Evolution of North America • The History of Paleozoic Mobile Belts • The Role of Microplates • The Breakup of Pangaea • The Mesozoic History of North America • GEO-FOCUS 18.1:Petrified Forest National Park • Cenozoic Earth History • Geo-Recap
OBJECTIVES 1 The Precambrian encompasses more than 88% of all geologic time, yet we know less about this episode in Earth history than we do about the other eras. 2 At the beginning of the Paleozoic, six major continents were present, and they assembled into the supercontinent Pangaea by the end of the Paleozoic. 3 The breakup of Pangaea took place in four general stages, beginning during the Triassic. 4 The geologic record of the Cenozoic is more thoroughly understood than the records of earlier eras. 5 An episode of widespread glaciation took place during the Pleistocene Epoch.