The Earth’s climate has, during its long history, oscillated between warm periods and cool periods, but the extreme ranges have remained within biological limits (Lovelock, 1982). Such oscillations have been attributed to a wide variety of natural phenomena such as perturbations in the Earth’s major orbital parameters, changes in the solar energy flux, changes in atmospheric gas components, changes in the particulate matter within the atmpshere such as volcanic dust, changes in ocean currents such as with El Niño, changes within biological life itself such as described by the Gaia hypotheses, changes in distributions of continents and oceans, and even combinations of several of these phenomena. The surface of the Earth is slowly but constantly being changed by geologic processes, and local weather and climate changes accordingly. The major cool periods of the past were, however, associated with times when there was land in a polar or subpolar position; warm periods were associated with times when land masses were in temperate or equatorial positions.
The space allotted for this short chapter does not permit discussion of a “normal” climate of the Earth, or even if the Earth has one. This short synthesis deals only with broad generalities, and gives a small sample of the various methods used to decipher our climatic changes during the Quaternary. Literature on this subject is vast and grows at a fast pace, but most of it concerns the Holocene and Wisconsin paleoclimatology; very little of it deals with pre-Wisconsin Quaternary.
The terrestrial system
Figures & Tables
Includes 5 topical chapters covering paleoclimates, dating methods, volcanism, tephrochronology, and Pacific margin tephrochronologic correlation, and 15 chapters of regional synthesis covering: the Pacific margin; the Columbia Plateau; the Snake River Plain; the major pluvial lakes of the Great Basin; the Basin and Range in California, Arizona, and New Mexico; the Colorado Plateau; the Southern and Central Rocky Mountains; the Northern and Southern Great Plains, Osage Plains, and Interior Highlands; the Lower Mississippi Valley; the Gulf of Mexico Coastal Plain and Florida; the Appalachian Highlands and Interior Low Plateaus; and the Atlantic Coastal Plain. A large, full-color geologic map of the Quaternary deposits of the Lower Mississippi Valley, in addition to correlation charts, tables, and cross-sections relating to other chapters, is also included.