Sediment Cores
Sediment deposited on the ocean floor provides useful clues about climate change. The shells of tiny marine animals called “forams” (foraminifera) may be preserved in sediment. Abundances of shells of warm-loving or cold-loving creatures reveal past temperatures. The chemistry of the shells also records the temperature and provides information about the composition of the water in which they grew.
Various types of rock and sand found on the ocean floor also provide clues to global ice coverage, since very large rock fragments could only have been carried into the open ocean by icebergs.
Cores taken from fresh-water lakes often contain the remains of leaves, seeds, wood, and pollen. Identifying the various types of vegetation in these cores indicates a great deal about the climatic conditions during the time the plants lived.
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Sediment Cores from the Castile Formation
These cores are approximately 260 million years old. Thicker light-colored layers indicate exceptionally warm summers. |
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