The prebatholithic history of Baja California extends from latest Precambrian through medial Cretaceous time. Late Proterozoic and Paleozoic shallow shelf deposits of the Cordilleran geocline extend into the northeastern part of the northern peninsula. Continental slope and basinal deposits of Devonian to Permian age were laid down along the eastern side of the northern peninsula. Lower Triassic shelfal deposits were deposited on top of Permian slope-basin deposits. From Late Jurassic through medial Cretaceous time volcanic-arc rocks and arc-derived detritus interfingered with cratonally derived sediment on both sides of what is now the Gulf of California.

East-vergent folds in middle Paleozoic...