Ingakslugwat Hills, Yukon Delta National Wildlife Refuge

The Ingakslugwat Hills volcanic field is in the Yukon–Kuskokwim Delta in western Alaska. It contains eight large craters and about thirty small pyroclastic cones in an area of some 500 km². The field contains unusual so-called "Ingakslugwat volcanoes", volcanic ridges up to 7 kilometres long and 400 metres high which are formed by pyroclastic material. They most likely formed by the interaction of permafrost with magma, seeing as they have a hydrovolcanic nature despite being high above the water table. ()