Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Hadean
Formation of the Earth
Earth's Atmosphere
Earth's Surface
Part of a meteorite that hit Arizona about 50,000 years ago.
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Moon Rock
Augustine Volcano

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Earth’s Atmosphere
The composition of Earth’s earliest atmosphere remains unclear and is a subject of active investigation by geologists. Some geologists believe that the earliest atmosphere included large amounts of nitrogen. Others believe that it was composed largely of carbon dioxide and water vapor, along with some other volcanic gases. These gases would have come from steaming vents and volcanoes that were common across the Earth’s surface. Early in the Hadean, Earth’s atmosphere was probably too hot to allow liquid water to condense, but fragments contained within younger rocks suggest that sedimentary rocks formed later in the Hadean, which implies the existence of surface water.

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Earth’s Surface

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