Pre-cambrian (or Precambrian) is a term used to describe the eons before the Cambrian. It lasted from about 4.567 billion years ago to about 542 million years ago. It starts with the beginning of the Earth, about 4.567 billion years ago. When it ends, there were many hard-shelled animals around. It is named after the Roman name for Cymru / Wales, because rocks thought to be from this time were first studied there.
The immediate Precambrian period is the Ediacaran.
References[change | change source]
- "Age of the Earth". U.S. Geological Survey. 1997. Retrieved 2010-08-06.
- Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved". Special Publications, Geological Society of London. 190: 205–221. doi:10.1144/GSL.SP.2001.190.01.14.
- Manhesa, Gérard; Allègrea, Claude J.; Dupréa, Bernard; and Hamelin, Bruno (1980). "Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics". Earth and Planetary Science Letters, Elsevier B.V. 47: 370–382. doi:10.1016/0012-821X(80)90024-2.CS1 maint: multiple names: authors list (link)
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