 In the north of the Province of Guadalajara, bordering Madrid and Segovia, is a mountain range forming part of the Sistema Central, among which can be distinguished the mountain ranges Pela, Ayllón, Somosierra, Barahona and Ministra, with the headwaters of the rivers Jarama, Cañamares and Henares.The Sistema Central also penetrates the Province of Toledo, which intersects a southerly part of the Sierra de Gredos, known as the Sierra de San Vicente, delimited on the north by the river Tiétar and on the south by the Alberche and the Tagus.On the northwest is the Sistema Ibérico, where there is important fluvial and especially karstic activity, which has given rise to such landscapes as the Ciudad Encantada, the Callejones de Las Majadas and the Hoces del Cabriel.