Coiling Direction of Globigerina pachyderma as a Climatic Index.

An interdependence between the geographical distribution of dextral and sinistral populations of the planktonic foraminifer, Globigerina pachyderma, and sea surface-temperatures is demonstrated. It is inferred that changes in dominant coiling direction at lower levels in sediment cores from the North Atlantic record southward shifts of isotherms during the last ice age.