Big Butte

The sign uses the butte's older name, and so do the BLM signs at the foot of its road; maps now call it Big Southern Butte. Emigrants on Goodale's Cutoff steered by it across the lava plain in the 1860s and watered at springs on its north slope, the only reliable water for miles. A road climbs to the summit, built for a fire lookout that was last staffed in 2004 and has since been taken down; the BLM still maintains the road. Hang gliders launch from its western end on summer weekends.

What the plaque says

Big Butte Towering 2,500 feet high, two overlapping rock domes form a 300,000 year-old butte that dominates this lava plain. After a hot flow of molten rhyolite (acidic rock) boiled up through older lava, a second rhyolite dome pushed up a block of earlier basalt on its northwest side. They took many thousands of years to reach their present shape, but geologically they are very recent structures. 436 Text prepared by the Idaho Historical Society Marker made & installed by Idaho Transportation Department

Where it stands

Worth the stop nearby

• Experimental Breeder Reactor I — 15 mi
  The reactor that lit four bulbs in 1951 also suffered the first accidental breeder meltdown, and two engines for a nuclear bomber sit outside.

More markers nearby

• Three Buttes — steps away
• Nuclear Reactors — 15 mi
• Lost River — 15 mi
• Elephant Hunters — 18 mi