The small-scale sequences of the Purbeck in the Jura Mountains indicate through their facies association and their shallowing-upward tendency a depositional environment which was very shallow and partly emergent, and which was influenced by cyclic fluctuations of sea-level. These fluctuations were probably related to the precession cycles of the equinoxes (periodicity 20 000 years). Sequence boundaries can be correlated over the entire platform and thus give a chronological framework which permits detailed paleogeographic reconstructions. Furthermore, correlation with the Purbeck in England permitted preciser dating of the formation boundaries.