Balanced Rock is made of two different rock formations. The rock itself is Entrada Sandstone, the primary arch-building formation in the park. The pedestal it sits on is part of the Carmel Formation, which erodes more easily.
Formations in the park are consantly changing. Note the small pillar to the right of Balanced Rock in the historic photo. That formation, dubbed "Chip Off The Old Block," fell in the winter of 1975-76.
On the Colorado Plateau, sparse rainfall and nutrient-poor soils facilitate slow rates of native plant growth and decay. Captured inadvertently by a scenic photo in the early 1920s, a dead juniper tree remains virtually unchanged nearly 100 years later. Nearby, two living junipers appear to have grown little. How long might a dead tree like this last where you live?
From 1944 to 2015, several million people from around the world have enjoyed North Window Arch. As we can see in this comparison, soil erosion is a serious concern as regional visitation increases.
The desert may look rugged, but its ancient shrubs and biological soil crusts have few defenses against trampling from human feet or off-road vehicles. You can us protect the desert environment by staying on established roads and trails.
A 1950s-era photo of the entrance to Arches National Monument
A 2010s-era photo of the entrance to Arches National Park