Energy/Environment What keeps nature's sandstone arches from falling? Oddly, it's gravity.

The photogenic sandstone arches and other surprising natural formations that delight many a tourist seem to defy gravity. Instead, they rely on it, researchers say.

By , Staff writer

Jerret Raffety/Rawlins Daily Times/AP/File

Photos of graceful sandstone arches, villages set deep into natural alcoves in cliffs, or gravity-defying rocks perched atop pedestals are staples for summer-vacation uploads to Flikr or Instagram.