Diamond Crater

Diamond Crater Outstanding Natural Area

Diamond Craters was recently established as Diamond Craters Outstanding Natural Area due to its unique volcanic landscape, as well as botanical and faunal diversity. It was named in 1874 after local rancher Mace McCoy's Diamond brand. The volcanic terrain covers an area of 23 square miles (about 60 square km) and represents one of the most recent volcanic centers in Oregon, next to the Cascade Volcanoes. This Quaternary-age basaltic volcanic complex is also one of the most diverse in North America, including aa and pahoehoe flows, cinder cones, spatter cones and spires, domes, and lava lakes. The craters formed sometime during the last 25,000 years as molten basalt rose through fissures and flooded the surface, which was then largely dry lake beds. Before the initial erupted material completely cooled, additional basaltic magma rose, arching the surface upward and creating 6 structural domes.

Diamond Craters is a volcanic field or small shield volcano in southeastern Oregon, about 40 miles southeast of the town of Burns. It consists of a 23 sq mi area of basaltic lava flows, cinder cones, and maars. The volcanoes are less than 60,000 years old, and some craters may be as recent as 6,000 years based on the sedimentation history in the lake-filled Malheur MaarDiamond Craters is a monogenetic volcanic field in southeast Oregon. The volcanoes are all Quaternary in age. Lava flows and tephra from the volcanoes cover an area of about 23 square miles (60 square km). Diamond Craters includes numerous features associated with basaltic volcanism including cones, explosion and collapse craters, fissures, and grabens.