Coral reefs, like tree rings, are natural archives of climate change. But oceanic corals also provide a faithful account of how people make use of land through history, says Robert B. Dunbar of Stanford University.
In a study published in the Feb. 22 issue of Geophysical Research Letters, Dunbar and his colleagues used coral samples from the Indian Ocean to create a 300-year record of soil erosion in Kenya, the longest land-use archive ever obtained in corals. A chemical analysis of the corals revealed that Kenya has been losing valuable topsoil since the early 1900s, when British settlers began farming the region.
Core samples from a large coral colony near Easter Island.