Evidence of the Ice Ages
Many subtle recorders of climate surround us. In the oceans, tiny marine organisms die and are incorporated into sediments that blanket the ocean floor. The chemical composition of their shells reflects the composition and temperature of the seawater in which they lived. The chemical makeup of coral skeletons can be used to reconstruct conditions in the tropics. Tree rings and lake bed sediments record seasonal variations on the continents, while ice cores record high-latitude climate changes.
Topic: Earth Science
Subtopic: Climate/Climate Change
Keywords: Climatic changes--Observations, Climatology, Corals, Ice cores, seawater, Sedimentation and deposition, Shells, Tree rings
For the last two million years, the climate of our planet has been mostly cold, with great ice caps covering much of Europe, Asia, and North America.
Tree rings are sensitive indicators of annual climate.
This marine sediment core from the tropics shows fine laminations of alternating light and dark layers.