ERTH 2403 Lecture 2: Lecture 2
2 Sep 2016
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Erth 2403 lecture 2 (origin of the ocean) Bombardment of the young earth by comets and asteroids: comets and asteroids outer of the solar system may have contributed to the formation of the. Earth"s surface water: frozen gas and water ice. Atmosphere (formed about 1. 5 million years ago: photosynthesis, ancestors of today"s green plants produced oxygen, oxygen oxidized minerals dissolved in the ocean and sediment, oxygen began to accumulate in the atmosphere oxygen revolution event. Evidence of photosynthesis: 3. 0 billion years ago, preserved photosynthetic blue-green algae, stromatolites: layer of algal mats and sediment forming mound, 2. 3-2. 0 billion years, vast reefs global immense oxygen production. >3. 0 billion years: no atmospheric oxygen yet, sedimentary rocks exposed to atmosphere, minerals (pyrite, uraninite) 2. 5-3. 0 billion years: b. i. fs: banded iron formation global sedimentary rocks, alternate layers of oxidized iron and chert (sio2) 1. 8 billion years: red beds = highly oxidized sedimentary rocks. Earth"s first atmosphere was swept away by radiation of the sun (solar winds)
