Malpaís de Nealtican, Volcanic terrain in Tianguismanalco Municipality, Mexico

The Malpaís de Nealtican is a field of extrusive igneous rock from Popocatépetl's most recent eruption, forming the volcano's easternmost slope on a plateau about 50 metres above the surrounding valley. It covers roughly 42.6 km² of Tianguismanalco and 1.6 km² of San Nicolás de los Ranchos, between the Xalapexco river to the north and the Apiaxco to the south. Its shallow arenosol and litosol soils support a dense pine-oak-madroño forest.

The malpaís is an extrusive igneous deposit from Popocatépetl's most recent eruption, forming the volcano's easternmost slope and part of the divide between the Puebla-Tlaxcala and Atlixco valleys. Its unconsolidated arenosol and litosol soils proved useless for farming, so the pine-oak forest persisted. In 2014 the municipality of Nealtican consolidated a Municipal Forest Guard to fight fires, curb illegal logging and run environmental education.

The name Nealtican comes from Nahuatl and the malpaís is bordered by San Buenaventura Nealtican, San Nicolás de los Ranchos, Tianguismanalco and San Baltazar Atlimeyaya. Local people collect firewood, produce charcoal and graze livestock on the land. Since 2014 the municipality's Guardia Forestal Municipal has fought forest fires, curbed logging and run environmental education work.

The malpaís sits on a promontory about 50 metres above the surrounding valley, with steep slopes that have long been quarried for tezontle building stone. Trails cross the pine-oak forest and meadows, and the main route climbs Cerro Teteolotitla or Teteólotl (2,550 m), the highest summit in the area. Recreational use remains limited and there is no management plan, so walk with care on the loose, rocky ground.

The rocky ground and poor soil make this place unsuitable for farming, which means the original forest remains intact. These natural conditions have protected the area from conversion to farmland while surrounding regions are heavily cultivated.