Stratigraphydefines the basis, concepts and methods of one of the oldest disciplines of Earth Sciences. Stratigraphy is a primary tool in dynamical and historical reconstructions in paleogeography, paleontology, tectonics, sedimentology as well as mineral prospecting. The first three chapters are devoted to the description of the main tools used to subdivide geological time and to construct a more precise chronologic scale. During this century this approach has been closely associated with the progress yielded by geochemistry, geophysics, plate tectonics, petroleum exploration and the Deep Sea Drilling Program. Correlation and dating, leading to reconstructions of paleogeography - a major step toward the knowledge of Earth history - is included. In a last chapter the principal stages of geohistory are described. Epoch for epoch plate dynamics, sea level and climate variations, environmental characters on continents and in oceans, and the link between cyclic interval activity, cosmic events and Earth history during the last 900 million years are outlined. Stratigraphical methods are then presented at their different scales of observation and synthesis.