The first green tinge on land
Microbial crusts turn bare rock into soil
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The Torridonian deposits of north-west Scotland preserve freshwater and terrestrial microbial ecosystems from around 1.2 billion years ago, including eukaryotic microfossils. Isotope data from older palaeosols suggest biological weathering was under way even earlier. The effect is cumulative and underrated: microbial weathering increases the release of phosphorus and other nutrients to the ocean, and draws CO₂ from the atmosphere. Several researchers link the gradual build-up of terrestrial microbial communities to the cooling that ended in Snowball Earth.
For children
Long before there were plants, thin crusts of bacteria and algae grew on the rocks beside rivers and lakes. They looked like a greenish film. But they did something important: they began breaking rock down into the very first soil.
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Part of Terra Saga — the story of Earth on a timeline. terrasaga.org