7 of 16Haleakala Highway, Maui, Hawaii

The valley seen is often mistaken for an extinct volcano, but this is not the case. The valley that crosses the southern part of Maui started as two valleys, one in the north and one in the south. As the porous volcanic rock eroded, the valleys extended toward the summit and finally merged, producing a valley that crosses the Haleakala mountain.

From: Ride Down the Volcano | Album: USA Grand Tour 2006