Annum
From Biocrawler, the free encyclopedia.
Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million years. It commonly used in geology and paleontology to signify time in the past. For example, 65 Ma indicates 65 million years ago.
Giga-annum, usually abbreviated as Ga, is a unit of time equal to 10^9 years. It commonly used in geology and paleontology to signify time in the past. For example, 4.55 Ga indicates 4.55 billion (or 4550 million) years ago.
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