I read in the NY Times a week or so ago about dating method to determine
approximately the time when glaciers retreated and rocks were uncovered. The
method involved, I believe, a beryllium isotope, and had a possible precision
of plus or minus 500 years.
I have not been able to find that article again, but some web searching
turned up some pages on 'cosmogenesis'. This involves cosmic rays, mostly
protons and mu mesons, bombarding silicas in rocks and producing Be-10 and
also Al-26. The beryllium-10 half-life is about 2.7 million years, so it
seems like a suitable vehicle for dating on the order of 10,000 - 20,000
years.
Does anyone have an inkling of how cosmic ray particles could create
beryllium 10 from oxygen and silicon?