Major events in the park's geologic history took place during the Paleozoic, Mesozoic and Cenozoic Eras. Read below to discover the specifics of these event. The oldest geologic events are discussed at the top of the page and more recent history is discussed at the bottom.owever, through techniques of geologic interpretation, scientists have constructed a timeline of geologic events that affected the Valley Forge area during the Paleozoic, Mesozoic, and Cenozoic eras. The geologic time scale above separates the geologic history of the Earth into major Eras and Periods.