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单词 Precambrian
释义

Definition of Precambrian in English:

Precambrian

adjective priːˈkambrɪənpriˈkæmbriən
Geology
  • 1Relating to or denoting the earliest aeon of the earth's history, preceding the Cambrian period and the Phanerozoic aeon.

    Compare with Cryptozoic
    Example sentencesExamples
    • The crest of the Blue Ridge is usually underlain with Precambrian or Cambrian igneous rocks.
    • Turquoise here was found as vein fillings and nodules in weathered Precambrian granite.
    • Plenty of suitable sedimentary deposits exist within the late Precambrian and Cambrian strata.
    • 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.
    • It extends upwards from a depth of about 6 km, at which depth Precambrian crystalline basement is predicted from seismic refraction studies.
    1. 1.1as noun the Precambrian The Precambrian aeon or the system of rocks deposited during it.

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 per cent 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 aeon. The Precambrian is now replaced in formal stratigraphic schemes by the Archaean, Proterozoic, and (in some schemes) Priscoan aeons

 
 

Definition of Precambrian in US English:

Precambrian

adjectiveprēˈkambrēənpriˈkæmbriən
Geology
  • 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
    Example sentencesExamples
    • 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.
 
 
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更新时间:2024/9/21 18:56:36