The sign says: "Missing Summit
"What may look like the summit crater is not a volcanic crater. On Haleakala Summit there was no massive blowout. The deep basin below is instead an erosional valley where wind, stream runoff, and landslides carried away loose cinders and soil during pauses in volcanic activity.
"High cliffs around the basin measure the enormous mass of material that has washed away through Ko'olau and Kaupo gaps.
"Deeper valleys once gouged the summit floor, but more recent eruptions -- visible lava flows and cinder cones -- partially refilled the basin. Today the summit climate of freezing and thawing loosens rock and accelerates erosion.
"Haleakala will erupt again: from this viewpoint, at least seven eruptions occured on the landscape in the past thousand years."
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