[Aztlan] AD or CE? (additional note on BP)

[David Hixson]

Not to add any confusion to this thread, but some listeros might see archaeologists or geologists use the abbreviation BP.
 
Unlike AD, BC, CE, and BCE, a date given as BP is based upon radiometric measurements, and stands for "Before Present".  However, "Present" is defined as 1950 (approximately when the first radiocarbon dates were published, and roughly when the world's natural cycles of atmospheric radiation were thrown off by nuclear explosions).  So, if you see a date that is marked as "BP" (or hopefully "cal BP", indicating a calibrated or calendrical radiometric date), subtract that number from 1950.
 
Examples - 
2000 BP = 50 BC (or 50 BCE)
1000 BP = AD 950 (or 950 CE)
 
Please note that the moderators of Aztlan accept all of the notational systems above, and do not ask our list members to use one or another.  Therefore threads like this one are important to post from time-to-time so that all members can read, understand and enjoy posts authored by individuals who may utilize such abbreviations.  Thanks for the question, Mario.
 
-Dave
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David R. Hixson
Aztlan Co-Moderator