Located along the southeast side of the Malheur National Wildlife Refuge is the Diamond Craters volcanic field. It lies about southeast of the city of Burns. This monogenetic volcanic field consists of a area of basaltic lava flows, cinder cones, and maars. A reexamination of old radiocarbon dates and interpretation of paleomagnetic data and new radiocarbon dates limits the eruption of volcanic vents in this volcanic field to the time period between 7320 and 7790 calendar years B.P.