Timbered Dome is the southeasternmost named Pioneer Mountain summit. It is located west northwest of Arco, Idaho. It is in fact, dome shaped and timbered. It can be approached via rough 4WD roads from both the east and the west. A good map will help you get there. See John Platt’s trip report.
Timbered Dome. John Platt Photo
Timbered Dome from Big Cinder Butte in Craters of the Moon National Monument. The Lost River Range in the background and Sheep Mountain in the White Knob Mountains to its left.
USGS Champagne Creek
The USGS triangulation signal on Timbered Dome looking north to the Lost River Range. Rick Baugher Photo 5-22-1994