| This view of the Picture Gorge Basalt is exposed along Rock
Creek (along Highway 26 about one mile west of the intersection of Highway
19). Stair step-like ledges represent individual flood basalt flows that
formed over a period of time beginning about 16 million years ago in the
region. Fossil soil profiles between the lava flows suggest quiet periods
lasting several 10,000 to 100,000 years occurred between eruptions. During
those intervals forest ecosystems redeveloped across the region (Fremd and others, 1994; USGS, 2010). |
