The Eureka Valley Sand Dunes are located in the southern part of Eureka Valley, in northern Inyo County in eastern California, in the southwestern United States. Although covering an area of only 3 square miles (8 km²), the dunes rise approximately 680 feet (207 m) above the surrounding valley floor, making them one of the highest dune fields in North America. Eureka Valley is a basin and range structural valley oriented northwest-southeast and enclosed by the Last Chance Range to the east and the Saline Range to the west. The Eureka Dunes themselves are located in the southeastern most tip of the valley and trend north-south, parallel to Last Chance Range. According to a USGS survey map, the surrounding mountain ranges contain rocks that date back to the Mississippian and Cambrian periods while the surficial deposits on the valley floor are made up mainly of alluvium dating to the Quaternary period. They are also classified as booming sand dunes, one of only about forty worldwide.