The 6500-m-thick section of Neogene and Quaternary fill in the Bekes basin (3900 km2) reflects a normal cycle of rift-related sedimentation that began in late Badenian time (16.5 Ma) when marine waters were shallow (<200 m). By late Sarmatian or early Pannonian time (12−10 Ma), lacustrine conditions prevailed and water depths in the basin increased as a result of basin subsidence rates that greatly exceeded sedimentation rates. The latest history of the basin, from approximately 5.78 Ma, reflects continuously shallowing waters, which resulted from sedimentation rates that were generally higher than basin subsidence rates. By late Pannonian time (4.25 Ma), water depths in the lake were 200–400 m, and continued shoaling culminated in the eventual disappearance of the lake in Pliocene time.