Earth Sciences 1083F/G Lecture 16: Lecture 16 - Earth's Earliest Life
23 Jan 2012
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Lecture 16 earth s earliest life y single celled prokaryote microfossils found in swaziland, south africa date to. 3. 5 billion years ago (archean eon) y stomatolite (constructed by cyanobacteria) found in north pole, western. Australia dated to 3. 5 billion years ago (archean eon) y filamentous prokaryote microfossils (most likely cyanobacteria) found in. Apex chert, marble bar, western australia date to 3. 46 billion years ago (archean eon) y banded iron formations from 2. 5-2. 0 billion years (proterozoic), some from. Between 4. 5 to about 2. 5 billion years ago, there was almost no oxygen present in the hydrosphere or atmosphere: 2. From 2. 5 to 2. 0 billion years ago, enough oxygen was dissolved in seawater to precipitate iron oxides: 3. By 2. 0 billion years ago, there was enough oxygen in the atmosphere to oxidize iron on land.
