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Precambrian
Subtopics:
Archaean (2 items)
Hadean (1 items)
Proterozoic (2 items)

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PDF Precambrian Time - The Story of the Early Earth [More info]
Explains what we know about the early history of the earth and how we study the deposits formed during that time to understand the formation of the earth and life.
Divisions of geologic time-major chronostratigraphic and geochronologic units [More info]
Revised geologic time scale indicating the ages of the lower bounds of chronostratigraphic and geochronologic units as they are currently known. Modifications to those ages made since the previous time scale was released (2007) are clearly marked.
Geology of the Chesapeake and Ohio Canal National Historical Park and Potomac River Corridor, District of Columbia, Maryland, West Virginia, and Virginia [More info]
Rocks representing a variety of tectonic and depositional environments outcrop along the canal and towpath and reveal the geologic history of the central Appalachian region from the Mesoproterozoic to Jurassic Period.
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