Mont Blanc massif led to calls to limit access to the most popular summits and for the mountains to be treated with greater respect. The Mont Blanc massif has provided numerous opportunities for academic research, dating back to the very first ascent of Mont Blanc in 1786 during which Michel Paccard carried scientific equipment to confirm it as the highest summit. In 1820, an ill-fated expedition led by Dr Hamel included pigeons intended for release at varying altitudes to measure the impact of reduced air density on their ability to fly. In 1890, Joseph Vallot built a small meteorological observatory at approximately between
Iron Mountain (Los Angeles County) a 30° to 50° angle on loose soil, decomposed rock, or through brush. Some approaches to the summit require high degrees of rock-climbing skill. One route over the ridgeline from nearby Mount San Antonio (Mount Baldy) is long, difficult, and dangerous. The south mountain slopes in summer are directly exposed to the sun. Some climbers stay at the ruins of the Allison Mine about below the summit. There are no facilities of any kind on the mountain. Iron Mountain (Los Angeles County) Iron Mountain is a mountain in the San Gabriel Mountains of Los Angeles County, California. It is within