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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] 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] See alsoReferences
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