The Giumalău Mountains represent the western part of the Rarău-Giumalău massif, a mountainous group of the Moldo-Transylvanian Carpathians, belonging to the mountain range of the Eastern Carpathians. As an aspect of the relief, the differences between the Giumalău Mountains and the Rarău Mountains are obvious, they derive primarily from their geological composition. Thus Giumalău is a mountain much older than Rarăul, his younger brother.