During deposition of the Green River Formation, ancient Lake Gosiute started as a fresh-water lake, then evolved to a saline, alkaline lake and finally ended as a fresh-water lake. This evolution reflects the change from a closed-basin hydrologic regime to an open-basin hydrologic regime. As a result, sedimentation in the Lake Gosiute system was strongly influenced by the relationship between evaporation and inflow of water into the basin. In the Green River Formation, stratification sequences, sedimentary structures, and mineralogy of lithofacies provide important insights into the evolution of the system and into the competing factors that determined the type of sediment accumulated in the lake and fringing environments. Carbonate sedimentation was strongly influenced by lacustrine transgressions and regressions across a very low topographic gradient. Terrigenous rocks reflect progradation of beach and deltaic shorelines during wetter climatic intervals when detritus that had been produced and stored in upland areas during preceding drier intervals was transported to the lake.