Cosmogenic isotope dating Sexylive porncam
These differences can be translated into a measure of time since the rocks were either first exposed to sunlight, or covered over and isolated from the cosmic ray flux.
Until just 20 years ago, when pioneering work in accelerator mass spectrometry (Elmore and Phillips, 1987), cosmogenic isotope systematics (Lal, 1988), and geologic applications (Craig and Poreda, 1986; Kurz, 1986) hit the presses, such conclusions were unreachable because many hypotheses regarding rates and dates of glacial processes were simply unfalsifiable.
In two short decades, we have learned so much about when glaciers and ice sheets retreated that it's hard to imagine a world where glacial boulders were not targets for dating.
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It's not surprising that the authors avoided sampling bedrock underlying the erratics.