Complex sentence: On September 18,1870, the Washburn-Langford-Doane Expedition entered the Upper Geyser Basin, eventually members of the expedition named seven geysers they observed in the basin.
Split into simpler sentences: On September 18,1870, the Washburn-Langford-Doane Expedition entered the Upper Geyser Basin. Eventually, members of the expedition named seven geysers they observed in the basin.