Transcript 1.2 Early Life - Spirit Math and Science

1.2 Early Life
CHAPTER 1: THE ABYSS OF TIME
Cameron Falls

Outcrop of Alberta’s oldest
sedimentary rock

The properties of this
sedimentary rock and its fossils
provide evidence of the
environment 1.5 billion years
ago

There is evidence that Alberta
bordered an ANCIENT OCEAN
where large rivers deposited
layers of sand, clay and silt
Life Gets its Start

The world’s oldest evidence of
life dates back 3.8 billion years

Life may have existed before
that but there is NO FOSSIL
evidence
Earliest life forms
Single-celled Bacteria
Hot Oceans

Early Earth did not have an environment to support life

Frequent volcanic eruptions

Poisonous gases (methane, hydrogen sulfide)

Oceans were more than 100 C

Atmosphere had little oxygen

Extreme bacteria-like organisms (archaea) were able to
tolerate this environment
A Breathable Atmosphere

1.5 billion years ago…

Cyanobacteria was able to thrive, growing and dying in
layers

As they layered they deposited large mounds of
calcium carbonate (limestone) called stromatolites

Stromatolites are Alberta’s oldest fossils

Cyanobacteria were one of the only early producers of
oxygen through photosynthesis

Cyanobacteria was the dominant form of life for 2 billion
years!
Stromatolites
Snowball Earth




Late Precambrian….
Icecaps covered most of the
planet for almost 10 million
years
Evidence of glaciers
advancing and retreating are
found all over the world
Changes in habitat during the
freezing the thawing lead to a
great increase in biodiversity
and the first complex
organisms