When was the Tertiary Period - when mammals became important?
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Tertiary Period

Moose
Moose

The Tertiary period begins with the catastrophe that killed off the dinosaurs, about 65 million years ago, and it lasts down to 1.8 million years ago. With nearly all of the dinosaurs gone, there was plenty of room on Earth for the mammals to have lots of babies, and soon there were all different kinds of mammals all over the Earth.

As the continents continued to drift apart, plate tectonics caused a lot of volcanoes. Some continents ran into each other: about 60 million years ago California ran into North America, causing the Rocky Mountains.

Himalayas
Himalaya Mountains

About 55 million years ago India crashed into Asia and made the Himalaya mountains, and about 30 million years ago Africa crashed into Europe and pushed the Alps up into mountains.

About six million years ago, the first people evolved out of the early primates in Africa. By 2.5 million years ago, these people were using stone tools and entering the Paleolithic period of human history.

The Tertiary period ended with the planet getting cool enough to cause the last big Ice Age, about 1.8 million years ago. The next age is the age we're still in now; we call it the Quaternary period.

Learn by doing: find these mountain ranges on a globe or map
Go on to the Quaternary period

Bibliography and further reading about the Tertiary period and geology:

List of Geological Eras
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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