 The Gettysburg Formation and other formations of the Newark Supergroup were deposited in the Gettysburg Basin, just one of many Triassic rift basins existing on the east coast of North and South America, which formed as plate tectonics pulled apart Pangaea into the continents we see today.The conglomerates within the formation were most likely alluvial fan or mudflow deposits, or possibly talus, eroding directly from the Precambrian and early Paleozoic rocks to the north and south.The sandstones and shales were most likely deposited in the flooded rift valley as deltas.