The Isalo Massif has been eroded by wind and water, resulting in deep canyons, sandstone domes, flat-topped mountains and "runiform" mountains - steep sided outcrops that have been dissected into odd-shapes.
The rugged landscape of the Isalo Massif has been shaped by natural forces, yielding dramatic features such as deep gorges, rounded hills, and peculiarly-shaped rock formations known as "runiform" mountains.