tritium dating of groundwater

["Karam, Andrew" <Andrew_Karam@URMC.Rochester.edu>]

My understanding is that groundwater dating by tritium measurements is not
"classical" geologic dating in that it does not look at parent/progeny
ratios.  Instead, hydrogeologists will look for a tritium spike, which was
likely deposited during the peak era of atmospheric nuclear weapons testing.
If this spike has moved, say, 50 miles from the nearest area of groundwater
recharge, then hydrogeologists can say that the water has moved 50 miles in
35 years, giving an average rate of about 1.4 miles per year.

Glaciologists use similar methods to date glacial layers.  Our glacial
geologist at Ohio State had a Tennelec that he used solely to look for a
gross beta spike (primarily tritium and C-14) in the ice layers.  When he
found that layer he knew that it had been deposited sometime in the early
1960s, probably around 1965 (if memory serves me right) which is when
fallout peaked in the Antarctic.

Andy

Andrew_Karam@URMC.Rochester.edu
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