Pico de Orizaba

It rises 5,636 metres (18,491 ft) above sea level in the eastern end of the Trans-Mexican Volcanic Belt, on the border between the states of Veracruz and Puebla.

[citation needed] This name is not, however, used by Náhuatl speakers of the Orizaba area, who instead call it Istaktepetl (Iztactépetl in the traditional orthography for Classical Nahuatl), meaning 'White Mountain'.

The insolation angle and wind redeposition on the northwest and north sides allow for constant accumulation of snow providing a source for the outlet glaciers.

On the north side of Orizaba, the Gran Glaciar Norte fills the elongated highland basin and is the source for seven outlet glaciers.

The terminal lobe of Lengua del Chichimeco at 4,740 m (15,550 ft), having a gradient of only 140 m/km (740 ft/mi), is a low, broad ice fan that has a convex-upward profile, a front typical of almost all Mexican glaciers.

The retreat of these tongues prior to 1994 produced much erosion downstream and buried their edges by ablation rock debris.

[5] The climate of Pico de Orizaba, like the Sierra Madre Oriental, varies greatly due to the change of elevation and prevailing winds.

Large amounts of precipitation fall on the eastern face of the volcano due to adiabatic cooling and condensation from the trade winds that bring moisture off the Gulf of Mexico.

The southern face mostly experiences a humid subtropical climate, (Cwa) with the highest annual temperatures in the month of April.

Due to katabatic winds the western side is dominated by steppe (BSk) creating a rain shadow below 2,600 m (8,500 ft) above sea level.

Over 4,300 m (14,100 ft) with an annual average low of −2 °C (28 °F), alpine tundra (ET) prevails to the summit; heavy snowfalls and blizzards are common throughout the year.

Snow on the south and southeast melts due to solar radiation, but continually remains on the north and northwestern faces.

Pico de Orizaba evolved in three stages, the most recent initiated about 16,000 years ago during the late Pleistocene and Holocene.

[6] The most violent eruption in the volcano's history is thought to have occurred around 6710 BC, reaching a magnitude of VEI 5, characterized by lava dome extrusion and pyroclastic flow.

A companion peak lying about six km to the southwest of Pico de Orizaba is the Sierra Negra, at 4,640 metres (15,223 ft).

Pico de Orizaba, as part of the Sierra Madre Oriental, forms a barrier between the coastal plains of the Gulf of Mexico and the Mexican Plateau.

During the Spanish Conquest of Mexico, Hernán Cortés passed through the foothills of Pico de Orizaba; the volcano and the surrounding mountains made his journey to Tenochtitlan more difficult and delayed him for many days.

During the mid-19th century Citlaltépetl was explored by many scientists, including the German botanist Hugo Fink, who was the first to record the numerous species of flora found on the volcano.

[citation needed] On December 16, 1936, President Lázaro Cárdenas, in an effort to protect the natural beauty of Pico de Orizaba, created a national park with an area of 19,750 hectares (48,800 acres) that included the volcano with the surrounding area and the settlements of Tlachichuca, Ciudad Serdán, La Perla, Mariano Escobedo, and Calcahualco.

The most frequented route begins from the base camp Piedra Grande Hut ("refugio") via the Jamapa Glacier, located at an elevation of 4,270 m (14,010 ft) above sea level.

The caldera can be circumnavigated with relative ease, although at one point this requires a short, exposed traverse of steep rock and ice above the Glacier Este.

The main peaks and glaciers of Pico de Orizaba
Pico de Orizaba looking south from atop Cofre de Perote
View of the standard route from the Stone Hut (Piedra Grande), shown in the bottom left of this photo - November 2007
Traverse of steep slope above Glacier Este during circumnavigation of crater rim. November 2008