Four Craters Lava Field

Four Craters Lava Field is a basaltic volcanic field located south east of Newberry Caldera in the U.S. state of Oregon.[1] The volcanic field covers about 30 square kilometers and post-dates Mount Mazama's eruption.[3] Four Holocene cinder cones are the source of the flows in the field and are aligned along a fissure trending N 30° W. The cones rise 75 to 120 meters above the flows and the distance between the northernmost and southernmost cones is about 3.5 kilometers.[4]

Four Craters Lava Field
Craters of the aptly named Four Craters Lava Field are seen here from the NW on Green Mountain.
Highest point
Elevation	4,924 ft (1,501 m)[1]
Coordinates	43°21′36″N 120°39′46″W[2]
Geography
Location	Lake County, Oregon, U.S.
Geology
Age of rock	Holocene[3]
Mountain type	volcanic field
Last eruption	< 50,000 years ago[4]

Closely related to the Four Craters lava field is Crack-in-the-Ground located at the southwest corner of the field. The eruptions from the field were accompanied by a slight sinking of the older rock surface. This shallow, graben-like sink is about 3 kilometers wide and extends to the south into an old lake basin. Crack-in-the-Ground marks the western edge of this small, volcano-tectonic depression and is nearly 9 meters deep and over a meter wide. The crack is the result of a tension fracture along a hingeline produced by the draping of Green Mountain lava flows over the edge of upthrown side of the concealed fault zone.[4]