El Pinacate and Gran Desierto de Altar Biosphere Reserve

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El Pinacate and Gran Desierto de Altar Biosphere Reserve: A Landscape of Dramatic Contrasts and Scientific Interest

The El Pinacate and Gran Desierto de Altar Biosphere Reserve, inscribed as a UNESCO World Heritage Site in 2013, spans over 714,566 hectares in the Mexican states of Sonora and the Tohono O'odham Nation. This vast reserve presents a unique and visually striking landscape characterized by dramatic contrasts, making it a site of great scientific interest.

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UNESCO Description of the World Heritage Site

The 714,566 hectare site comprises two distinct parts: the dormant volcanic Pinacate Shield of black and red lava flows and desert pavements to the east, and, in the west, the Gran Altar Desert with its ever changing and varied sand dunes that can reach a height of 200 metres. This landscape of dramatic contrast notably features linear, star and dome dunes as well as several arid granite massifs, some as high as 650 metres. The dunes emerge like islands from the sea of sand and harbour distinct and highly diverse plant and wildlife communities, including endemic freshwater fish species and the endemic Sonoran Pronghorn, which is only to be found in northwestern Sonora and in southwestern Arizona (USA). Ten enormous, deep and almost perfectly circular craters, believed to have been formed by a combination of eruptions and collapses, also contribute to the dramatic beauty of the site whose exceptional combination of features are of great scientific interest. The site is also a UNESCO Biosphere Reserve.

UNESCO Justification of the World Heritage Site

Criterion (vii): The property presents a dramatic combination of desert landforms, comprising both volcanic and dune systems as dominant features. The volcanic shield in the property boasts a wide array of volcanic phenomena and geological formations, including a small shield-type volcano. The most visually striking feature is the concentration of a total of 10 enormous, deep and almost perfectly circular Maar (steam blast) craters, believed to originate from a combination of eruptions and collapses. The property is visually outstanding through the stark contrast of a dark-coloured area comprised of a volcanic shield and spectacular craters and lava flows within an immense sea of dunes. The dunes can reach 200 meters in height and contain linear dunes, star dunes and dome dunes, displaying enormous and constantly changing contrasts in terms of form and color. In addition to these predominant features there are several arid granite massifs emerging like islands from the sandy desert flats, ranging between 300 and 650m high. The combination of all these features results in a highly diverse and visually stunning desert landscape.

Criterion (viii): The property’s desert and volcanic landforms provide an exceptional combination of features of great scientific interest. The vast sea of sand dunes that surrounds the volcanic shield is considered the largest and most active dune system in North America. It includes a diverse range of dunes that are nearly undisturbed, and include spectacular and very large star-shaped dunes that occur both singly and in long ridges up to 48km in length. The volcanic exposures provide important complementary geological values, and the desert environment assures a dramatic display of a series of impressive large craters and more than 400 cinder cones, lava flows, and lava tubes. Taken together the combination of earth science features is an impressive laboratory for geological and geomorphological studies.

Criterion (x): The highly diverse mosaic of habitats is home to complex communities and surprisingly high species diversity across many taxonomic groups of flora and fauna. More than 540 species of vascular plants, 44 mammals, more than 200 birds and over 40 reptiles inhabit the seemingly inhospitable desert. Insect diversity is high despite not being fully documented. Several endemic species of plants and animals exist, including two freshwater fish species. One local endemic plant is restricted to a small part of the volcanic shield within the area. Large maternity caves of the migratory Lesser Long-Nosed Bat, which is an important pollinator and seed dispersal vector are found within the property. Noteworthy species include the Sonoran Pronghorn, an endemic subspecies restricted to the South-western Arizona and North-western Sonora and threatened by extinction.

Encyclopedia Record: El Pinacate y Gran Desierto de Altar Biosphere Reserve

El Pinacate and Gran Desierto de Altar Biosphere Reserve is a biosphere reserve and UNESCO World Heritage Site managed by the federal government of Mexico, specifically by Secretariat of the Environment and Natural Resources, in collaboration with the state governments of Sonora and the Tohono O'odham.

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IUCN World Heritage Outlook

The 2025 Conservation Outlook on El Pinacate and Gran Desierto de Altar Biosphere Reserve reports the following assessment:

Source: International Union for Conservation of Nature (IUCN) · View assessment