Sierra Madre

Sierra Madre, mountain system, Mexico, the country's chief range, enclosing the central plateau of Anáhuac. The Sierra Madre system consists of three major chains: the Sierra Madre Oriental and the Sierra Madre Occidental define the eastern and western margins of the central Mexican Plateau, while the Sierra Madre del Sur extends along the southern coast. Anáhuac, located south of Mexico City, is often included with the Sierra Madre.

The Sierra Madre Occidental stretches SSE from the border between the United States and Mexico, extending more than 1,100 km (680 mi) along the western coast of Mexico towards Guadalajara. The Occidental, the most continuous range, has an average altitude of about 2,440 m (8,000 ft) and contains numerous deep canyons. Its highest points are the Nevado de Colima (4,339 m/14,236 ft) and Volcán de Colima (3,850 m/12,631 ft). The range contains the famed silver mines of the Spanish conquistadores, which are said to have produced the richest yields of silver ever known.

The Sierra Madre Oriental system stretches south-east in parallel ridges from the Big Bend area of the Río Grande to Monterrey, where it continues south to join Anáhuac near Puebla. In the Oriental range occur Pico de Orizaba (5,610 m/18,406 ft), Popocatépetl (5,452 m/17,887 ft), and other volcanoes. Copper, lead, and zinc deposits are found amidst the range's deep caves, sink-holes, and steep narrow valleys.

The Sierra Madre del Sur stretches from the southern end of the Sierra Madre Occidental range east to the Isthmus of Tehuantepec. It has significant deposits of gold, silver, iron ore, and lead. The Cordillera de Anáhuac is an irregular young volcanic plateau 2,743 m (8,999 ft) high, connecting the Sierra Madre Occidental and Sierra Madre Oriental ranges south of Mexico City.

Vegetation in the Sierra Madre varies with elevation and moisture. The primarily temperate climate supports highland oak and pine forests. On some windward slopes, cloud forests contain giant broad-leaved evergreens. Because rainfall varies, lowland vegetation ranges from desert species in the dry north-west to tropical species in the southern and eastern portions.