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Geologic Time 12/17/13. 6-5 pgs. 151-155 Put your homework on the box IN: If the history of the Earth was the length of one calendar year, what do you think is the date of the arrival of modern humans ?. 7:40 PM on December 31. Geologic Time.
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Geologic Time 12/17/13 6-5 pgs. 151-155 Put your homework on the box IN: If the history of the Earth was the length of one calendar year, what do you think is the date of the arrival of modern humans ?
Geologic Time Scientists know about the history of the Earth by analyzing rock layers and the fossils they contain.
Grand Canyon The Colorado River has cut the canyon exposing rock layers that represent nearly 2 billion years of geologic time.
The Grand Staircase Extends the geologic time scale Include Zion Canyon and Bryce Canyon
The Geologic Time Scale Geologic Time Scale – divides Earth’s 4.6 billion year history into distinct intervals of time.
Precambrian Supereon 4.6 billion years ago - 540 million years ago Only simple celled organisms existed during this era Accounts for 88% of geologic time
The geologic time scale is divided into four major parts called eons.
Hadean eon 4.6 billion years ago – 3.8 billion years ago The only rocks that scientists have found from this eon are meteorites and rocks from the moon.
Archean eon 3.8 billion years ago – 2.5 billion years ago The earliest known rocks on Earth formed during this eon.
Proterozoic eon 2.5 billion years ago – 540 million years ago The first organisms with well-developed cells appeared during this eon.
Phanerozoic eon 540 million years ago – present The rock and fossil record mainly represents the Phanerozoic eon. This is the eon in which we live.
Paleozoic Era 540 - 248 million years ago Plants, fish, insects and amphibians start to appear
Paleozoic Era Ended with a mass extinction Nearly 90% of all species became extinct
Mesozoic Era 248 - 65 million years ago The Age of the Reptiles - Dinosaurs
Mesozoic Era Ended with a mass extinction About 50% of all species became extinct
Cenozoic Era 65 million years ago - present The Age of Mammals
4.6 Billion Years – Wing Span The distance from the fingertips to the wrist of the other is the Precambrian All complex life is in one hand You could use a nail file to destroy human history
Glue in the Diagram OUT: What future event might mark the end of the Cenozoic era?