Sources
Help build the largest human-edited directory on the web.
Submit a site - Become an editor
Wikipedia. Licensed under the GNU Free Documentation License.
Are you an expert in this subject? Join the discussion and share your knowledge at Wikipedia.org.
Myr
From Wikipedia, the free encyclopedia
- This article is about the unit of time. For the Magic: the Gathering creatures, see Creatures of Magic: The Gathering.
Myr is often used in geology and astronomy as a unit of one million years. The "M" is the SI prefix for Mega or million, with "yr" simply an abbreviation for "year".
Often the "M" is shown in lowercase, as in "100 myr", which is an incorrect usage, because a lowercase "m" would signify milli, or thousandths, such that "100 myr" would indicate a period of just over a month. "Myr" itself is often considered incorrect, with some preferring to use "My", as "y" is considered the proper abbreviation for year.
Related to Myr is "Ma", or Mega-annum. Ma is used to denote a specific number of millions of years ago, but it is not (should not be) used to describe a duration of time, so: the Cretaceous started 145 Ma and ended 65 Ma, but it lasted for 80 Myr (or 80 My). More often, the term "Mya" (million years ago) is used in these contexts.
 |
This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |