Guadarrama, Sierra de (syārˈrä ħā gwäħäräˈmä) [key], mountain range rising from the plateau of central Spain, N of Madrid, and extending c.120 mi (190 km) between the Tagus and Douro rivers. The rugged mountains rise to Pico de Peñalara (7,972ft/2,430 m), the highest peak. The range is crossed by several passes, such as the Guadarrama and Navacerrada, which link Madrid with Segovia. The passes are usually blocked by heavy winter snowfalls. Numerous streams have been dammed and supply water for irrigation, hydroelectric-power generation, and municipal needs. Largely forested, the mountains yield fine timber. There are skiing resorts on the slopes.