Figure 6.9

SCIENTIFIC INQUIRY: How do paleoclimatologists reconstruct ancient climates? Natural archives of information about Earth’s past can be found in a wide range of environments. In each of the settings shown here, layers are formed that record the changing environmental conditions. Layers can be formed through biological growth, as in tree rings and corals; through the settling of material by gravity, as in lake sediments, marine sediments, and glaciers; or through nonliving growth, such as mineral deposits in caves. Scientists extract cores of these materials and analyze the layers to gain an understanding of past environments and how they change through time.

(From top left to bottom right: Bruce Gervais; Hickerson/FGBNMS/NOAA; © Auscape/UIG/Getty Images; © Rod Benson; Lonnie G. Thompson, Byrd Polar Research Center, Ohio State University; IODP/TAMU; John Beck, IODP/TAMU)