"Although lower in height than its neighbor to the north, Mount Rainier, massive Mount Adams rises above a lower topographic base and is second in volume only to Mount Shasta among volcanoes of the Cascade Range. The Mount Adams volcanic field includes the 200 cu km Mount Adams complex andesitic-dacitic stratovolcano, elongated along a NNW-SSE line, and more than 60 flank vents. Volcanism began about 940 thousand years ago (ka), with three main cone-building stages occurring at about 500, 450 and 30 ka. Adams was active throughout the Holocene, producing two dozen minor explosive eruptions from summit and flank vents. Six Holocene lava flows are located on the flanks between 2100 and 2600 m altitude. The most voluminous Holocene lava flows, some of which traveled 10 km or more, were emplaced between about 7 and 4 ka. The latest eruption about 1000 years ago produced a minor tephra layer and possibly a small lava flow down the east flank."  -Smithsonian Volcano Archive
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