Earth’s History

__________________ - a timeline that organizes the events in Earth’s history

Like a calendar extending from Earth’s formation to the present

Divided into eons, eras, periods, and epochs

Earth’s History

www.fas.org

•________-the largest group; divided by the Cambrian boundary (about 550 million years ago) when the variety of life forms explodes; billions of years long

•____________: mass extinctions mark the boundaries between the eras; hundreds of millions years long

•_______________: blocks of time when a unique rock series was laid down; tens of millions of years long

•________________: divisions of the most recent periods; several million years long

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•Typically form in ______________________, however:

•May form in rocks

•Amber

•Petrification

•Asphalt

•Frozen Fossils

•______________________ - any naturally preserved evidence of animal activity

•__________-a cavity in rock where a plant or animal was buried

•___________-created when sediment fills in a mold and becomes rock

History of Change

•The fossil record reveals a history of environmental change. Why?

•Studying the relationship between older and younger fossils

•Fossils of organisms that lived during a relatively short, well-defined geologic time span

•Found in rock layers throughout the worldAmmonites 230-208

MYA

louisvillefossils.blogspot.com/2010/01/remark...

brianlean.wordpress.com/2008/08/

Trilobite ~400 MYA

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