Highlighting twenty years of U.S. scientific research conducted since the International Geophysical Year (IGY) of 1957-58, this volume marks a turning point in the history of polar investigations and provides a lucid summary of the contributions of many distinguished scientists. The authors provide an overview of major polar research programs, past and present; explore concepts derived, from highly interrelated aspects of physical and life sciences; and seek to offer a glimpse of future polar science and polar development. The introduction briefly describes major physical, biological, and interdisciplinary research programs, as well as the magnitude, extent, and international character of contemporary polar science. Twenty years of polar biological investigations are then reviewed, and subsequent chapters address principles and advances in meteorology, physical oceanography, glaciology, and the geological evidence that hears on the origin of Antarctica. These physical sciences delineate a matrix for the polar biospheres and provide a background for understanding the major categories of structure and dynamic functioning of the marine ecosystem, polar marine mammals, adaptational physiology, and terrestrial biotic adaptations.