The Earth is a work-in-progress, an evolving planet whose vital signs-as expressed by earthquakes, volcanic eruptions, and shifting plates-are still strong. In a geological time frame, nothing on earth is permanent: ocean basins open and close, mountains rise and fall, continental masses accrete and separate. There is a message here for all who live, for an infinitesimally brief time, on the moving surface of the globe. This course uses the plate tectonics model-one of the fundamental scientific accomplishments of this century-to interpret the processes and products of a changing Earth. The emphasis will be on mountain systems (on land and beneath the oceans) as expressions of plate interactions. Specific topics include the rocks and structures of modern and ancient mountain belts, the patterns of global seismicity and volcanism, the nature of the Earth's interior, the changing configurations of continents and ocean basins through time, and, in some detail, the formation of the Appalachian Mountain system and the geological assembly of New England. Readings will be from a physical geology textbook and primary source supplement, selected writings of John McPhee, and references about the geology of the Northeast. Lectures, three hours a week; labs (several involving field work), two hours a week; one required all-day field trip to the Connecticut Valley, and the highlands of western Massachusetts. Evaluation will be based on two hour-tests, weekly lab work, and a scheduled final exam.