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Ancient Shellfish Tell 10,000 Year History of El Ni?o Cycles
date:Aug 12, 2014
ells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.

While in graduate school, Mr Carr had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.

The shells provide one to three year long records of monthly temperature of the Pacific Ocean alo

12/24 05:39