Inland dunes are a rare Coastal Plain habitat unique to Delmarva Peninsula ecosystems. Along parts of Sussex County's Nanticoke River shore and Inland Bays watershed, cooler, drier conditions 13,000 to 30,000 years ago, together with strong winds, created grassy ridges with quickly draining, nutrient-poor sandy soils. Natural fire helped maintain the sunny open spaces that allowed specialized plants and animals to survive in this harsh environment. Species adapted to these conditions include wild lupine, blueberries, stunted pines, and other dune plants. Wild lupine is especially important because its deep taproots help it endure dune conditions, and it serves as a host plant for the globally rare frosted elfin butterfly and its caterpillar larvae. Without wild lupine, this endangered butterfly cannot complete its life cycle. Much of Delaware's inland dune habitat has been eliminated or degraded by increased development, logging, off-road vehicle use, and overgrazing by deer. The State of Delaware has identified inland dunes as a Habitat of Conservation Concern. At Delaware Botanic Gardens at Pepper Creek, five inland dunes have been created to support biodiversity, preserve Delaware's coastal character, and educate the public about this unusually rare habitat. These dunes surround the Dogfish Head Learning Garden Wetland and Outdoor Classroom.