posted by Briana .
I have a picture that shows what scientists think parts of North America looked like 300 million yrs ago. ie, trees, plants , insects, rocks. How do scientists know what North America looked like so long ago, if there were no people around to see it?
Fossils. By studying fossils and also the geological record one can reconstruct how the Earth looked like.
See also this program about the first trees:
Geologists, paleontologists, hydrologists, and others, study the landscape, the continental plates, fossils, etc and draw conclusions from those studies about various time frames.
Fossils and radioactive dating techniques. It is possible to assign an age to layers of earth at different depths.
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