ERTH 2403 Lecture 2: Lecture 2
26 Apr 2016
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Hydrosphere (two theories on how it was created): outgassing: no free oxygen. Volcanic gases emitted by volcanic venting (water vapour, carbon dioxide, nitrogen, methane, ammonia, sulphur dioxide) Hot vapour rose (formed clouds in the cool atmosphere) No water could form (because earth"s surface was very hot) After millions of years earth"s surface became cooler (water accumulated in basins and began to dissolve mineral) Repeated process of evaporation, cooling and rain fall = *ocean formed 4 billion years ago: 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. Comets and asteroids may have contained frozen gas and water ice. Some scientists reject this theory because using techniques the study of hydrogen on comets does not relate to the hydrogen on earth. Photosynthesis: ancestors of todays green plants produced oxygen. Oxygen oxidized minerals dissolved in the ocean and sediments.
