Precambrian

The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, 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.

Precambrian
~4600 – 538.8 ± 0.2 Ma
Chronology
Proposed subdivisionsSee Proposed Precambrian timeline
Etymology
Synonym(s)Cryptozoic
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitSupereon
Stratigraphic unitSupereonthem
Time span formalityInformal
Lower boundary definitionFormation of the Earth
Lower boundary GSSPN/A
GSSP ratifiedN/A
Upper boundary definitionAppearance of the Ichnofossil Treptichnus pedum
Upper boundary GSSPFortune Head section, Newfoundland, Canada
47.0762°N 55.8310°W / 47.0762; -55.8310
GSSP ratified1992

The Precambrian is an informal unit of geologic time,[1] 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 538.8 million years ago (Ma), when hard-shelled creatures first appeared in abundance.


Share this article:

This article uses material from the Wikipedia article Precambrian, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.