The Short Story of Ubehebe Crater in Death Valley National Park

CalVO geologists Judy Fierstein, Wes Hildreth, and Duane Champion investigated the sequence of rocks to determine whether the 15 craters formed as several independent eruptions over hundreds of years from a long-lasting, deep magma source, or whether they formed at one time.

The scientists are confident that the craters are monogenetic—created during one explosive episode when magma interacted with groundwater, over several days, weeks or months (but certainly not over hundreds of years). Their evidence: first, dozens of layers of rocks ejected during successive eruptive pulses are "conformable"—no time is represented by erosion or anything else between them, so all layers must have fallen during a short-lived eruption sequence. Second, they note that the composition of basaltic cinder samples does not vary—meaning that a single batch of magma fed the multi-crater phreatomagmatic episode. Third, measured paleomagnetic directions are almost exactly the same; again, not much time could have passed between crater-forming pulses.

Short-lived eruptive sequences like the ones that formed Ubehebe Craters are common in volcanically active areas (for example, throughout the Cascade Range). This is the only young volcano in Death Valley National Park, which was otherwise a volcanically quiet area for the last million years. The new research will be presented at the 2016 Geological Society of America Cordilleran Section meeting at the beginning of April.

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