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Earth review 3

name: ______________________________
Across
The period that begins about 800 million years after Earth formed and lasted for about 1.4 billion years.
The geologic era that spans from the formation of Earth around 4.5 b.y.a. to about 544 m.y.a.
When a large percentage of all known living species die out in a relatively short amount of geologic time.
The second most recent era on the geologic time scale, spanning from 245 m.y.a. to 65 m.y.a; often called the "Age of Dinosaurs."
The geologic era from 570 m.y.a. to 245 m.y.a. that is characterized by an explosion of life.
The death of an entire species.
Down
The first period in Earth's history, so named because it was thought to be like Hades.
To release gas.
The third, and last, period in the Precambrian, that lasted nearly 2 billion years.
Sedimentary layers formed by micro-organisms.