8 julio, 2024

Sierra Madre del Sur: location, relief, climate, flora

The Sierra Madre del Sur It is the southern part of the extensive Sierra Madre mountain range that stretches throughout Mexico. Although the western region is the one that presents the greatest variety of both inhabitants and fauna and flora, the forests of the Sierra Madre del Sur are rich in small species and plants exclusive to the region.

The Sierra Madre was completely formed approximately 66 million years ago, in a creation process that lasted about 190 million years. The uplifting and creation of all the land that was uplifted to form this mountain range occurred in conjunction with the formation of the American Rocky Mountains.

The shape of the Sierra led to the creation of three different divisions to better identify them: Sierra Madre Occidental, Sierra Madre Oriental and Sierra Madre del Sur. The Sierra Madre del Sur is considered one of the most important high mountains in Mexico, along with the Mesa del Sur and the mountains of Chiapas.



The geological process that led to the creation of the Sierra Madre left an apparent division into three parts.

The Sierra Madre Oriental owes its shape to various earth movements in the rocks that occurred in the Cretaceous period. In central Mexico, there was a great deal of volcanic activity in the past that shaped the region’s mountains.

The Sierra Madre del Sur is divided from the rest of the Mexican mountains and presents peculiar characteristics of the area, although similar to those of the rest.


The southern zone of the mountain range extends over 1,000 kilometers in the southern territory of Mexico, from Michoacán to Guerrero, on the Tehuantepec isthmus located in eastern Oaxaca. The highest point of the Sierra Madre del Sur is almost 4 kilometers above sea level.

This part of the range joins the Eje Volcánico Transversal in central Mexico, but in the west it is divided by the Balsas River, which later connects with the Tepalcatepec River. There is only one highway that crosses this geographical expansion from Acapulco to Mexico City.

Although separated by a river, the southern mountains of Michoacán and Coalcomán are also considered part of the Sierra Madre del Sur mountain range.


The deepest part of the Sierra Madre del Sur is bounded by a narrow, discontinuous coastal plain that spans all of southwestern Mexico and the Balsas River to the north.

A wide variety of narrow ridges and steep valleys with many geological irregularities form the Southern Highlands. Many of the crests of these mountains reach considerable elevations, and are quite irregular in shape with rocks present in various areas.

Volcanic activity

The rest of the Sierra Madre has plenty of evidence of past volcanic activity, but the volcanic cover of the Sierra Madre del Sur has been lost over time and no longer has the high presence it had millions of years ago.

However, at the bottom of these mountains you can find dissected rocks millions of years old. It is perhaps the oldest dissected rock in Mexico.

There are very few flat areas in these mountains, presenting irregularities throughout its entire territory. To the south of this area of ​​the Sierra Madre there is an abrupt cut that divides this formation and joins it with the ocean. That part of the sierra stands out from the rest and towers over the entire Isthmus of Tehuantepec.


The climate of the Sierra Madre del Sur is mainly humid and warm. However, this also varies with altitude. The lower areas of the Sierra Madre tend to have relatively hot weather during the day and a bit cooler at night, dropping to around 22 degrees Celsius.

In the highest areas there are high mountain ecosystems, but it is not completely cold. The temperature remains warm and in some areas it is considered semi-cold.



The Sierra Madre del Sur presents a biodiversity exclusive to this area, especially with regard to its flora. Throughout its extension there are 350 different species of orchids unique to this part of the mountain, which cannot be seen anywhere else in the world.

coniferous trees

It mainly presents a gigantic expanse of coniferous trees, such as the pine-oak forests of the Sierra Madre del Sur. This forested extension has an expansion of approximately 61,000 square kilometers, being the main habitat of hundreds of plants and small animals exclusive to the region.

This forest expands along the entire coast of Mexico and occupies almost the entire Sierra Madre del Sur.

The most common plants in the region are holm oak forests, cloud forests, pine-oak forests, and spruce forests. However, its frequency changes depending on elevation and rainfall.

Each type of tree grows at different altitudes, between 1,900 and 3,000 meters above sea level. The forest is categorized as a coniferous subtropical ecoregion and is one of the most extensive forested expanses that can be found throughout the Mexican territory.


The Sierra Madre del Sur presents a great biological variety in its complex rock formations.

Butterflies, beetles and reptiles

This area has one of the most diverse populations of butterflies and beetles in all of Mexico. In addition, it has a large number of unique reptiles with its exclusive species of toads, frogs and salamanders.


The mammals of the Sierra Madre del Sur are similar to those of the western cordillera, but it also has exclusive species of bats, mice, skunks, and shrews.


The region is especially rich in bird species: it features unique species of orioles, eagles, and nutcracker birds.

All this makes the Sierra Madre del Sur one of the richest biogeographical zones in the world.


Sierra Madre Mountain System, Henry J. Bruman George C. Engerrand, (nd). Taken from Britannica.com
Mexico, Gordon R. Willey Michael C. Meyer Howard F. Cline Angel Palerm Ernst C. Griffin Henry Bamford Parkes, February 3, 2018. Taken from Britannica.com
Sierra Madre del Sur pine-oak forests animal and plant species, (nd). Taken from globalspecies.com
Sierra Madre del Sur – Physiographic Province. (n.d.). Taken from paratodomexico.com
Sierra Madre del Sur pine-oak forests, (nd). June 24, 2017. Taken from Wikipedia.com
Sierra Madre del Sur pine-oak forests, (nd). June 24, 2017. Taken from Wikipedia.com

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