Introduction
The Precambrian (or Pre-Cambrian, sometimes abbreviated pЄ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.
The Precambrian (colored green in the timeline figure) is an informal unit of geologic time, subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago (Ga) to the beginning of the Cambrian Period, about 541 million years ago (Ma), when hard-shelled creatures first appeared in abundance.
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Did you know...
- ... that δ34S values in certain Archean pyrites suggest that sulfate-reducing organisms were present 3,470 million years ago?
- ... that Australia has the earliest mineral grains of Earth's history in the form of Hadean zircons?
- ... that the La Loche Formation can include clasts of Precambrian gneiss?
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Eras and periods
- Hadean Eon
- Archean Eon
- Proterozoic Eon
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