When Antarctica split apart from Australia during the Oligocene,it was isolated over the south pole. A cold current begant to flow aroung Antarctica,and glaciers began to form.
The climate began to warm again during the Early Miocene.During the Late Pliocene through the Pleistocene, the norhtern hemisphere experienced extensve glaciation,or an ice age.
Tectonic Events
Western North America had been tectonically active throughout the Cenozoic.The orogenic events that occured at the end of the Mesozoic uplifted massive blocks of crust to form the Rocky Mountains.
Subduction in the West
The Cascade Mountains in the Pacific Northwest are the result of the subduction of an oceanic plate beneath the western coast of North America.During the MIocene the North American Plate was forced over the East Pacific Rise resulting in the creation of the San Andreas Fault.
Hot Spots in the West
Hot spots are mantle plumes that rise to Earth's surface. Some of the hot spots that occur in the western Unted States are related to the continuing subduction along the western coast of North America.
Continental Collisions
The rocks at the top of Mt.Everest are Ordovician marine limestones. Tectonic forces have pushed what was the seafloor during the Ordovician to the top of the world! Africa also drifted north after the breakup of Pangea and collided with Eurasia,a narrow sea called the Tethys Sea seperated the two continents.