So there is that wide spread layer of Volcanic ash, known as the Laacher Sea Tephra which is widely used as a dating marker but how old is it, itself?//<![CDATA[ aax_getad_mpb({ "slot_uuid":"f485bc30-20f5-4c34-b261-5f2d6f6142cb" }); //]]>

All with 95% confidence interval:

K-Ar dating gives: 12,900 +/- 560 years before present

A carbon date of the last tree ring of an ash burried tree gives: 12,985 +/- 75 years before present

Counting individual annual sediment layers in a lake finds 12,880 +/- 120 years before present

A so called multi proxy trick combining all kind of techniques gives: 12,859 +/- 116 years

The only common time frame of all these is 12,910 to 12,975 years but the average value is 12.906 years. How would you calculate a statistically acceptable 95% confidence interval?

Thanks

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# Dating a volcano

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