The state is divided into five geographical regions: The Sierra Gorda, El Semidesierto Queretano, Los Valles Centrales, El Bajío Queretano and La Sierra Queretana. The Sierra Gorda is located in the north of the state and is part of the Sierra Madre Oriental, specifically in a subprovince called the Huasteco Karst. It is found in the municipalities of Arroyo Seco, Jalpan de Serra, Landa de Matamoros, Pinal de Amoles and San Joaquín and covers an area of 3,789km2 or 32.2% of the state. The topography is rugged, with high elevations and steep valleys. It is a conjunction of mountains and hills formed mostly by limestone, with wide contrasts in climates and vegetation. They range from near desert conditions to forests of pine and holm oak to the tropical rainforests of the Huasteca area in the state of San Luis Potosí. The Sierra Gorda was made a biosphere reserve in 1997, the Reserva de la Biosfera de la Sierra Gorda, to protect its abundance of species and ecosystems. In 2001, the area was registered with the Man and the Biosphere Programme of UNESCO. This area is managed by la Comisión Nacional de Áreas Naturales Protegidas of the Secretariat of Environment and Natural Resources federal agency.