[Coyoteman]

"Living samples from a freshwater lake on limestone terrain have been known to give a radiocarbon date of up to 1600 BP." [p 166]

That is one of the poorest things to use for a radiocarbon date. Freshwater shellfish from limestone environments are equally bad.

There are ways to calibrate those kinds of samples but it is easier to use more reliable materials to start with.

There is a large body of literature on this problem.

[SunkenCiv]

The soil of Santorini is enriched in C12, and this has an impact on the RC dating of stuff on the island, including plants grown in the soil (samples from still-living plants having a much higher RC date). Seems like thermoluminescence, electron spin resonance, and perhaps other forms of radiological dating would be a better choice.