Mountains at the junction of the Arroyo and Jalpan Rivers in Arroyo Seco
Semidesert and mountains in the municipality of Peñamiller
The region is on a branch of the Sierra Madre Oriental mountain range and consists of a series of mountain chains that run northwest to southeast, formed 240 million years ago. Most are made of limestone, formed by sea beds from the Jurassic and Cretaceous periods. Later there were intrusions of volcanic rock, especially in the eastern portion in Hidalgo state, from which come the mineral deposits of the area. The limestone has been affected by erosion to form the Huasteca Karst, and the area contains a large number of caverns, and pit caves (sótanos), some of which extend for hundreds of meters in depth. All of the Sierra Gorda is marked by very rugged terrain, which includes canyons and steep mountains. Altitudes range from just 300 meters above sea level in the Río Santa María Canyon in Jalpan to 3,100 m asl at the Cerro de la Pingüica in Pinal de Amoles. The most important elevation in the Hidalgo area is the
Cerro Cangandhó which has an altitude of 2,820 m asl. Rainfall also varies greatly from 350 mm to 2,000 mm per year. The micro-environments of the region range from conifer forests, oak forests, mostly found on mountain peaks, banana and sugar cane fields in the deeper canyons. On the east side, there are deciduous forests. On the west side, bordering the Mexican Plateau, there are desert and semi desert conditions, with a variety of cacti and arid scrub brush. Among its mountains are the peaks associated with the
Sierra Alta de Hidalgo, the pine forests of Zamoarano, the
Extoraz Canyon and the slopes of the Huazmazonta, the inter-mountain valleys where the five missions are found and the rolling hills leading into La Huasteca. The wide variations of altitude and rainfall favor a wide variety of flora and wildlife.
There are three main rivers in the Sierra Gorda, all of which are part of the Pánuco River basin. These are the
Santa María River, the
Extoraz or Peñamiller River and the Moctezuma River. All three pass through deep canyons and tend to form borders between the states and municipalities of the region. Santa María marks part of the border between Querétaro and San Luis Potosí, and the Moctezuma River marks part of the border between Querétaro and Hidalgo. The Tula and Moctezuma Rivers meet in the Sierra Gorda of Hidalgo. Here, the Moctezuma River Canyon extends for twelve km and rises 480 meters above the floor.
The climate of the region depends on altitude and the fact that the mountains form a natural barrier against the prominent source of moisture, the Gulf of Mexico. The east side of the mountains gets significant more rainfall than the west, as the altitude extracts moisture from the clouds. Forests and even rainforests are found in the east, while the west is dominated by desert and near desert conditions. In the east, mornings in the high mountain areas usually bring cloud cover and fog. The most moisture falls in the northeastern edges of the regions, where it merges into La Huasteca proper, in San Luis Potosí and Hidalgo. In the entire region, the coldest temperatures occur between December and January, with high temperatures in April and May. Temperatures vary widely depending on altitude with an annual average of 13 °C in the higher elevations such as Pinal de Amoles to 24 °C in lower areas such as Jalpan. In the highest elevations, frosts and freezes are not uncommon. In 2010, the Sierra Gorda had it first significant snowfall in eighteen years in the municipality of Pinal de Amoles, with temperatures of −4 °C. In some places, the cover was 15 cm deep.
Because of its great variety of ecosystems, the Sierra Gorda has one of the diverse ecologies in Mexico, with one of the largest number of species of plants and animals. Species in danger of extinction include the jaguar, puma, the black bear, the green parrot, the Veracruz partridge, and the
Humboldt butterfly, mostly due to human activities. Endangered plant species include the biznaga gigante (Echinocactus platyacanthus), the chapote (
Diospyros riojae), the guayamé (Abies guatemalensis), the magnolia (Magnolia dealbata) and the peyote (Lophophora diffusa). monarch butterflies can be found in the area as well, as they pass through to their wintering grounds on the State of Mexico-Michoacán border . There have been plagues in the forests of the area due to the recent drought conditions. The most serious is a bark beetle (Dendroctonus adjunctus) and mistletoe (Arceuthobium sp.). The drought conditions have been blamed on global climate change. Areas in Querétaro and Guanajuato have been declared as biosphere reserves. The Sierra Gorda in Hidalgo has not, but it still contains a large number of important ecosystems.
Poverty levels are high in the area despite the ecological and cultural richness. A number of indigenous communities still inhabit the region. The eastern part in Hidalgo is dominated by the Otomi . The far north of Querétaro still has significant communities of Pames, and Guanajuato has a number of Chichimeca groups. Tourism has been a recent phenomenon here, as the area’s ecological importance becomes more widely known.
In Jalpan de Serra, there is a museum dedicated to the history and geography of the Sierra Gorda region. The museum building was first constructed in 1576 as a fort and military outpost. It was reconstructed at the end of the 16th century. It was remodeled in 1990 and was inaugurated as a museum in 1991, with a collection of pieces that range from the pre Hispanic era to the Reform War. It has eight halls for exhibits, a bookstore, an audiovisualroom, a temporary exhibit hall, research center and library. It organizes educational, ecological and cultural events.
There is an annual cycling event called "Escalera del Infierno" (Hell's Ladder) which extends over the Sierra Gorda in Querétaro in March. The event begins in Bernal, through Ezequiel Montes, Cadereyta and ends in San Joaquín, for 137 km, 28 km of which are uphill.