from googling: http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.html http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.ht... "The low activity

from googling: http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.html http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.ht... "The low activity of the carbon-14 limits age determinations to the order of 50,000 years by counting techniques."