Sand Mountain is a cluster of 23 cinder cones NW of Mt Washington, Oregon. The youngest eruption took place to form Lost Lake cinder cone at the north end of the chain about 2000 years ago.
Most of the 23 basaltic and basaltic-andesite cinder cones of Sand Mountain volcanic field are aligned along a N-S trending line immediately west of the Cascade crest NW of Mount Washington. A secondary trend of alignment in NNW and NNE direction intersects the N-S line near the largest cinder cone, Sand Mountain.
Geologically young lava flows from vents on the western side were erupted between 3000-4000 years ago. The lava flows traveled mostly to the west, blocking local drainages and forming several small lakes.
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