1.   Hodgson counted seal hairs in sediment cores from Signy Island in the South Orkneys.

2.   The researchers collected a sediment core from a lake on the Ardley Peninsula, sectioned it and dated the sections using radiocarbon techniques.

3.   The researchers, whose latest study was published in the journal Science, examined sediment cores from Lake Chichancanab in the Yucatan.

4.   We have sediment cores that show fluctuations in sardine and anchovy scale depositions.