giga-annum

English

Alternative forms

• gigaannum, (rare) gigannum, (abbreviation) Ga

Etymology

From giga- +‎ annum.

Noun

giga-annum (plural giga-annums)

1. Gigayear, a billion years.
   • 2000, A. S. Weber, Nineteenth-Century Science: An Anthology, →ISBN, page 387:

     Geophysicists today estimate the earth’s age to be 4.5–4.6 Ga (giga-annums = 1 x 10⁹ years) based on data from lead isotopes (Dalrymple 403).

   • 2014, Sophia Ahmed et al., “A Haploid System of Sex Determination in the Brown Alga Ectocarpus sp.”, in Current Biology, volume 24, number 17, →DOI:

     We report here the sequencing and genomic analysis of the SDR of Ectocarpus, a brown alga that has been evolving independently from plants, animals, and fungi for over one giga-annum.

   • 2018, Ronald Martin, Earth’s Evolving Systems: The History of Planet Earth, 2nd edition, →ISBN, page 214:

     Possible cyanobacteria from the Apex charts of western Australia, which have been dated at ~3.5 (giga-annums, or billions of years).

Translations

10⁹ years — see gigayear