The study of stratified rocks (stratigraphy) in relation to cycles of formation and destruction. First-order cycles, over periods of 200–400 million years, are linked to the formation and breaking apart of supercontinents. Second-order cycles (super cycles), lasting 10–100 million years, are linked to plate tectonics. Third-order cycles (mesothems), over 1–10 million years, are linked to plate movements and glacial and interglacial episodes. Fourth-order cycles (cyclothems) are linked to the Milankovitch solar radiation curve. Fifth-order cycles (minor cycles), over 0.01–0.2 million years, are linked to the Milankovitch curve and astronomic forcing.