Comment: 02:51 - 03:54 (01:03)
Source: Annenberg/CPB Resources - Earth Revealed - 10. Geologic Time
Keywords: "James Sadd", "geologic time", "geologic age", planet, water, life, oxygen, gas, atmosphere, "multi-cellular organism", plant, animal, dinosaur, extinction, humans, "Industrial Revolution"
Our transcription: One way to illustrate the immense panorama of geologic time is to draw an analogy using the time period that we can easily relate to -- so let's condense the entire age of the Earth into one calendar year.
On this scale, the Earth and it's neighboring planets were formed on January 1.
By sometime in early March, the planet had cooled sufficiently to allow water to stand in pools on its surface.
The very earliest forms of life appeared by late March.
And oxygen gas became an important part of Earth's atmosphere beginning sometime in late July.
Multi-cellular organisms appeared by October 25th.
But it was not until late November that plants and animals were abundant on land.
On about December 15th, the dinosaurs appeared, but disappeared in a sudden mass extinction on December 25th.
The first humans appeared at about 11:20 p.m. on December 31.
And the Industrial Revolution began less than a second and a half before midnight.
Geology School Keywords