<P> Valley of Fire State Park is a public recreation and nature preservation area covering nearly 46,000 acres (19,000 ha) located 16 miles (26 km) south of Overton, Nevada . The state park derives its name from red sandstone formations, the Aztec Sandstone, which formed from shifting sand dunes 150 million years ago . These features, which are the centerpiece of the park's attractions, often appear to be on fire when reflecting the sun's rays . It is Nevada's oldest state park, as commemorated with Nevada Historical Marker #150 . It was designated as a National Natural Landmark in 1968 . </P> <P> Valley of Fire is located 50 miles (80 km) northeast of Las Vegas, at an elevation between 1,320--3,009 feet (402--917 m). It abuts the Lake Mead National Recreation Area on the east at the Virgin River confluence . It lies in a 4 by 6 mi (6.4 by 9.7 km) basin . </P> <P> Complex uplifting and faulting of the region, followed by extensive erosion, have created the present landscape . The rough floor and jagged walls of the park contain brilliant formations of eroded sandstone and sand dunes more than 150 million years old . Other important rock formations include limestones, shales, and conglomerates . </P> <P> Prehistoric users of the Valley of Fire included the Ancient Pueblo Peoples, also known as the Anasazi, who were farmers from the nearby fertile Moapa Valley . Their approximate span of occupation has been dated from 300 BC to 1150 AD . Their visits probably involved hunting, food gathering, and religious ceremonies, although scarcity of water would have limited their stay . Fine examples of rock art (petroglyphs) left by these ancient peoples can be found at several sites within the park . </P>

What caused the unusual landscape at the valley of fire