Definition of Precambrian in US English:



  • 1Relating to or denoting the earliest eon, preceding the Cambrian period and the Phanerozoic eon.

    The Precambrian extended from the origin of the earth (believed to have been about 4,600 million years ago) to about 570 million years ago, representing nearly ninety percent of geological time. The oldest known Precambrian rocks have been dated to about 3,800 million years old, and the earliest living organisms date from the latter part of the eon. The Precambrian is now replaced in formal stratigraphic schemes by the Archean, Proterozoic, and (in some schemes) Priscoan eons

    Compare with Cryptozoic
    • ‘By the early years of the twentieth century, as the geology of the continents began to be better known, it was realized that Permian and Precambrian glacial deposits occur virtually on all continents and at low latitudes.’
    • ‘Turquoise here was found as vein fillings and nodules in weathered Precambrian granite.’
    • ‘The crest of the Blue Ridge is usually underlain with Precambrian or Cambrian igneous rocks.’
    • ‘It extends upwards from a depth of about 6 km, at which depth Precambrian crystalline basement is predicted from seismic refraction studies.’
    • ‘Plenty of suitable sedimentary deposits exist within the late Precambrian and Cambrian strata.’
    1. 1.1as noun the Precambrian The Precambrian eon or the system of rocks deposited during it.