Mountains are often considered a metaphor for force and stability. Paradoxically they constitute fragile systems, even more fragile the more powerful they seem. The major characteristics of mountain landscapes are intimately tied to the topography, which constitutes the main factor of control in the organization of space. The altitude and the slope determine many environmental characteristics and the uses of the soil and, especially, they condition the appearance of limits or thresholds for the occurrence of different processes. Topography is responsible for the two most outstanding characteristics of mountainous landscapes: heterogeneity and instability.
