Paleogeography and Geologic History
The following maps and text summarize our understanding of the Tertiary geologic history of Arizona. These two figures show Tertiary sequences of events in central Arizona. The list of geologic events and chart correlating volcanic, tectonic, and sedimentary events are color-coded to emphasize the events and deposits of the region.
Table sumarizing Tertiary events in Arizona.
Chart showing sedimentologic, tectonic, and volcanic Tertiary units and events in Arizona.
Tectonic Evolution of Arizona as Shown by Restored Cross Sections
These restored cross sections show the tectonic evolution of Arizona from the Late Cretaceous to the Recent. The sections run from SW Arizona to the southern Colorado Plateau and are based on geophysical data from McCarthy and Parsons (1994). Note changes in crustal thickness through geologic time across the sections. Magnitude of extension and model for crustal evolution after Spencer and Reynolds (1989).
Large-format cross sections
Small-format cross sections
The paleogeographic maps illustrate each step of the geologic history. Two series are shown. One covers all of Arizona from Late Cretaceous to Pliocene. The other focuses on central Arizona and covers the Middle Tertiary conglomerates (Oligocene?) and younger through the Pliocene. Ages of many of the Tertiary sedimentary deposits are only partially constrained, although included Tertiary volcanic clasts greatly assist in dating some deposits.
Present physiography of Arizona
Late Miocene to Pliocene paleogeography of Arizona.
Middle Miocene paleogeography of Arizona.
Early Miocene paleogeography of Arizona.
Oligocene paleogeography of Arizona.
Eocene paleogeography of Arizona.
Latest Cretaceous to Paleocene paleogeography of Arizona.
Central Arizona Paleogeography
Present physiography of central Arizona.
Late Miocene to Pliocene paleogeography of central Arizona (deposition of Verde Formation).
Middle Miocene paleogeography of central Arizona (extrusion of Hickey Basalt).
Late Oligocene (?) to Early Miocene paleogeography of central Arizona (deposition of upper unit, Beavertail conglomerate).
Oligocene (?) paleogeography of central Arizona (deposition of middle unit, Beavertail conglomerate).
Oligocene (?) paleogeography of central Arizona (deposition of lower unit, Beavertail conglomerate).