Chapter 1: The Abyss of Time 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

Single-celled Bacteria 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