Cenozoic Era Geologic Time

Eons: Hadean ▫ bya Archaean ▫ bya Proterozoic ▫2.5 bya – 543 mya Phanerozoic 543 mya- present

At only 66 million years long, the Cenozoic is only 1.4% of all geologic time ▫or only 20 minutes on our hypothetical 24- hour clock for geologic time Geologic Time in 24-hours

When the Cenozoic began, semitropical (angiosperm) forests covered much of North America, and many mammals dwelled in these forests Many event that began during the Cenozoic continue to the present, including ▫the ongoing erosion of the Himalayas in Asia and the Andes in South America, ▫ the origin and evolution of the San Andreas fault, ▫and the origin of the volcanoes that make the Cascade Range. Cenozoic Events

Geologists divide the Cenozoic Era into two periods of unequal duration ▫The Paleogene Period  66 to 23 million years ago  includes Paleocene, Eocene, and the Oligocene epochs ▫The Neogene Period  23 million years to the present  Includes Miocene, Pliocene, Pleistocene, Holocene epochs Older system: ▫Tertiary and Quaternary periods Neogene and Paleogene

Vast exposures of Cenozoic sedimentary and igneous rocks in western North America ▫record the presence of a shallow sea in the continental interior, ▫terrestrial depositional environments, ▫lava flows, ▫and volcanism on a huge scale in the Pacific Northwest. Cenozoic Rocks Are Accessible

Paleocene Fort Union Formation, Montana

Wasatch Formation, Bryce Canyon

Miocene Lovejoy Basalt, California

The progressive fragmentation of Pangaea accounts for the present distribution of Earth's landmasses Because the geographic locations of continents profoundly influence the atmosphere and hydrosphere, moving plates also directly affect the biosphere Cenozoic Plate Tectonics

During the Triassic Period Paleogeography of the World

During the Jurassic Period Paleogeography of the World

During the Late Cretaceous Period Paleogeography of the World

Spreading ridges such as the Mid-Atlantic Ridge and East Pacific Rise were established, along which new oceanic crust formed and continues to form However, the age of the oceanic crust in the Pacific is very asymmetric, because much of the crust in the eastern Pacific Ocean basin has been subducted beneath the westerly moving North and South America plates Spreading Ridges

Age of Ocean Basins

Eocene Epoch Cenozoic Paleogeography of the World

Miocene Epoch Cenozoic Paleogeography of the World

Present Day Cenozoic Paleogeography of the World

Another important plate tectonic event ▫Northward movement of the Indian plate and its eventual collision with Asia Simultaneous northward movement of the African plate ▫Caused the closure of the Tethys Sea ▫Causes tectonic activity that currently takes place int an east–west zone from the Mediterranean through northern India End of the Tethys

North and South America continued their westerly movement as the Atlantic Ocean basin widened Subduction zones bounded both continents on their western margins ▫Situation changed in North America as it moved over the northerly extension of the East Pacific Rise and it now has a transform plate boundary Americas Move West