This is not a guide to identifying rocks, but a guide to land formation. It shows how to recognize the key field marks and how to use them to read geological history: plate movements, earthquakes, glaciers, rivers, seas, and other forces that have shaped a particular patch of earth over millions of years--and are still shaping it. Each geological region of eastern North America is described vividly and illustrated with detailed maps and cross sections, as well as color photographs that show the characteristic field marks of the best examples of the various formations and to get a clear sense of the history of the land.