This Ironwood Forest National Monument is made up of 129,000 acres and contains a significant system of cultural and historical sites covering a 5,000-year period. Possessing one of the richest stands of ironwood in the Sonoran Desert, the monument also encompasses several desert mountain ranges including the Silver Bell, Waterman, and Sawtooth, with desert valleys in between. Elevation ranges from 1,800 to 4,261 feet. Three areas within the monument, the Los Robles Archeological District, the Mission of Santa Ana del Chiquiburitac and the Cocoraque Butte Archeological District are listed on the National Register of Historic Places. The monument is a travel corridor for illegal immigrants traveling from Mexico. All suspected illegal activities should be reported to BLM or local law enforcement authorities. Stay safe by avoiding contact with persons exhibiting suspicious behavior or engaged in dangerous activities. Drive with caution and look for fast-moving vehicles and pedestrians on back roads. Some roads are rugged: high clearance or four-wheel-drive vehicles are recommended in those areas.