addition of free oxygen
They PHOTOSYNTHESIZED
Fossils aren't but the life that made them is.
Changes in climate
geologic time scale
Scientists do not know the answer to this question.
What are two ways that's scientists can study earths climates history
epoch
Nitrogen
In sedimentary rock.
Historical geology.
History can not be measured it can only be recorded, studied or experienced.
Gravitational potential energy.
precambrian era
No movement
to die
because
Astronomy This is the study of the earth and physical structure and history