before the present.

Myr is deprecated in geology, but in astronomy Myr is standard. Where "myr" is seen in geology, it is usually "Myr" (a unit of mega-years). In astronomy, it is usually "Myr" (Million years).

Debate

In geology, a debate remains open concerning the use of Myr (duration) plus Mya (million years ago) versus using only the term Ma. In either case, the term Ma is used in geology literature conforming to ISO 31-1

1.Previous
3.Next