 As it is still the site of Oak Ridge National Laboratory and Y-12 National Security Complex, scientific development still plays a crucial role in the city's economy and culture in general.The earliest substantial occupation of the Oak Ridge area occurred during the Woodland period (c. 1000 BC – 1000), although artifacts dating to the Paleo-Indian period have been found throughout the Clinch Valley.Two Woodland mound sites—the Crawford Farm Mounds and the Freels Farm Mounds—were uncovered in the 1930s as part of the Norris Basin salvage excavations.