One of the most interesting elements of the reserve is the Peñalara cirque, created by a glaciar. It is located between the summit of Peñalara and the Younger Sister, on the eastern slope of both peaks. The base of the cirque has an altitude of 2 to 2.05 km, and its sides rise from this elevation to 2.2 and 2.4 km. There are also three other cirques of lesser size and importance. One of these is the cirque of Pepe Hernando, located some 500 m to the south of the Lake of Carnations. Its size is a quarter of Peñalara's, and its base rises to approximately 1.9 km. The others are the cirques of the Regajo de la Pedriza y Brezal. Each has a moraine at its lower part, a rocky zone with a relatively gentle slope that was produced by the track of an ancient glacier. Besides cirques and moraines, there exists a series of walls with elevations greater than 200 m aligned north to south, extending north and south from the principle cirque.