Top: Science: Earth Sciences: Paleontology: Terminology: H



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Hadean

The earliest subdivision of the Precambrian, spanning the time between the formation of the Earth, about 4.5 billion years ago, and the start of the Archaean era, 3.8 billion years ago. This interval predates the period of true geologic time since no rocks of this age are known on Earth, with the exception of a few meteorites.


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Hauterivian

European stage of the Lower Cretaceous, spanning the time between 122 and 118 million years ago.


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Holocene

An epoch of the Quaternary period, spanning the time from the end of the Pleistocene (8,000 years ago) to the present. It is named after the Greek words "holos" (entire) and "ceno" (new).


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Hydrogeology

The science that deals with subsurface waters and geologic aspects of surface waters. 



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