About The Fields at Jasper Ridge The Fields at Jasper Ridge in Upper Milford Township takes its name from the area’s rare jasper mineral and its prime view. Mining of the jasper in this area by the Leni Lenape Indian tribe is believed to be one of the oldest industrial sites in North America. Original inhabitants of the land, the Leni Lenape recognized the value of jasper. A unique, natural resource, found in a variety of stunning colors, jasper is a hard, workable stone that they skillfully converted into arrows and high-quality tools. The Leni Lenape traded jasper with other tribes along the East Coast and up into New England by following the animal trails along the area’s abundant waterways.