Monahans Sandhills State Park preserves part of a vast West Texas sandhill system in the southern Llano Estacado near Monahans. Opened in 1957, the 3,840-acre park protects dunes that can rise 70 feet above the surrounding land and are formed from unusually pure, fine quartz sand linked to late Pleistocene buildup. Though it appears desert-like, the area is a semi-arid ecosystem with enough rainfall and accessible groundwater to support specialized life, including Havard oak and a range of animals. The dunes are constantly reshaped by seasonal winds yet generally remain in place, making the park an important refuge for both a distinctive landscape and recreation on the sand.