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Cyclic variation among foraminifera
and environment on geologically short timescales

Click images or text for larger images.

Location of the study site
(Blake Nose transect)
approximately 500 km east of Florida (image from Adam Klaus)

Covariation in sediment color, relative abundance
of different foraminifera, and stable isotopic ratios in
foraminifera.

Similar cyclic variation is also seen in clay mineralogy and elemental abundances. These correlated trends demonstrate links among climate, continental weathering, oceanic productivity, and foraminiferal assemblages; the types of covariation provide clues as to the nature of those links. Leading hypotheses to explain the biological changes are Milankovitch driven cycles in the intensity of upwelling or in the amount of continental input.
(after MacLeod et al., 2001)