Sec. 13.1 – Precambrian Time
- The ____________ time period last from _____ years
ago, until the start of the _______ period, _____ years
later
- Comprises _____ of the ____________________
- Precambrian Atmosphere:
o Similar to gases released in present day volcanic
eruptions

 No _____________
o As the planet cooled, _______________condensed
causing rains that filled the low areas, forming
_____________
o The first ____________on Earth did not need
_____________
o Primitive organisms used _______________, using
_____________
o _____________ began to accumulate in the
_______________ about _______billion years ago, and
organisms requiring _____________to live began to
appear
- Precambrian fossils
o ____________organisms; more complex plants and
animals had not yet ______________
o _________________(a material deposited by
ancient_____________) are the most common
Precambrian fossils