Gunung Gede and Pangrango are a part of the great belt of volcanoes which extends in an arch through Sumatera, Java and the Lesser Sundas. These volcanoes were formed during the Quarternary period between 3 million years ago and the present time. Pangrango and Gede are thus comparatively new mountains geologically, though the former is the older of the two, no longer displaying any sign of volcanic activity, while Gede is still semi-active with a well-defined crater within which gases escape from fumaroles.

Gunung Gede (2,958 m) and Pangrango (3,019 m) are connected by a high saddle at about 2,500 m. Slopes are very steep and are incised by valleys forming steep-sided ridges between them radiating out towards the flat plains of Bogor-Cianjur and Sukabumi.