In eastern Siberia, a perfect circle of rock contrasts with the surrounding topography. The 6-kilometer- (3.7-mile-) wide ring looks like an impact crater, or the caldera of an extinct volcano, but it is neither. Kondyor Massif was formed by the intrusion of igneous, or volcanic, rock that pushed up through overlying layers of sedimentary rock, some of them laid down more than a billion years ago.
The Blue Mountains rise to a broad plateau not far west of Sydney, Australia. In the heart of the mountains lies the Grose Valley, bounded by sheer 300-meter (1,000-foot) cliffs.
In the arid terrain of the western slopes of the Andes Mountains in southern Peru, very little vegetation exists to soften or obscure the rugged topography. In the central part of the state of Ayacucho, pictured in this satellite image, the mountains are dramatically sliced by dozens of nearly straight, parallel canyons that point southwest toward the Pacific coast.