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Sierra Madre Occidental

geography Maturity 5-7 Next article →

The Sierra Madre Occidental is a massive mountain range system in Mexico.

It runs from the northwest to the southeast through northwestern and western Mexico. The range follows the Gulf of California. Its name means "Western mother mountain range" in English. This system is part of the American Cordillera. That is a nearly continuous chain of mountains. It forms the western backbone of the Americas. It stretches from Alaska all the way down to Chile.

The landscape is defined by a high plateau. This plateau sits on top of volcanic rock. Below this volcanic layer is a basement of metamorphic rock.

Durango volcanic field
Durango volcanic field

Rivers have cut deep valleys into this plateau over time. These rivers follow folds in the rock. This process has created many steep canyons. The most famous is Copper Canyon in Chihuahua.

Barranca del cobre 2
Barranca del cobre 2

This canyon is larger and sometimes deeper than the Grand Canyon. The western slopes are often more eroded because they are wetter.

Geological history explains how these mountains formed. During the Cretaceous period, an event called the Laramide orogeny increased magmatism. Magmatism is the movement of molten rock. This created the first major igneous series in the area. Later, during the Eocene, volcanism created andesitic and rhyolitic formations.

Sierra.madre.occidental.volcanics
Sierra.madre.occidental.volcanics

These rocks often contain gold and silver. In the Oligocene, ash flows became the main type of deposit. These ash flows created a series of ignimbrite formations. Ignimbrite is a type of rock made from volcanic ash. These formations cover a very large area. There are ten identified calderas in this province.

The mountains play a vital role in the local climate. They act as a barrier that changes weather patterns. The range forces air upward, which increases rainfall.

Cascada Basaseachi
Cascada Basaseachi

This extra water creates wet ecosystems in an otherwise dry land. These wet areas act like islands of biodiversity. They are very different from the surrounding desert landscapes. Oak forests are the most common plants here. These forests extend from the mountains down into the lowlands.

Water from these mountains is essential for life. The mountains provide 90% of the water used for irrigation in the watershed. Rivers like the Yaqui, Fuerte, and Humaya drain into the Gulf of California.

Rio Santiago
Rio Santiago

Other rivers, like the Nazas and Aguanaval, drain into a closed basin. Humans have built many dams to capture this water. For example, the Aguamilpa Dam was started in 1991. However, damming rivers has caused environmental concerns. In some areas, damming has led to soil depletion and drying lakes.

Many different groups of people call these mountains home. The Tarahumara people live in the northern region near Durango.

Tarahumaras1
Tarahumaras1

Further south, the Cora people live in towns like Jesús María. Some people live in small family groups near farms. Others live in mining communities, such as San Martín de Bolaños. The town of Creel in Chihuahua has about 5,000 people. It is a stop on a train line. Traveling can be difficult because there are few paved roads.

Today, the region faces many modern challenges. The main industries are agriculture and forestry. These industries can cause land degradation. Many native populations oppose some of these practices. Logging has also caused more erosion on the hillsides. This shows how human activity and nature are closely linked in the Sierra Madre Occidental.

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🖼️ Images & Media (8)
File:Barranca del cobre 2.jpg
Barranca del cobre 2.jpg
File:Cascada Basaseachi.jpg
Cascada Basaseachi.jpg
File:Rio Santiago.jpg
Rio Santiago.jpg
File:Durango volcanic field.jpg
Durango volcanic field.jpg
File:Sierra.madre.occidental.volcanics.JPG
Sierra.madre.occidental.volcanics.JPG
File:Sierra Madre Occidental....jpg
Sierra Madre Occidental....jpg
File:Tarahumaras1.jpg
Tarahumaras1.jpg
File:Villa close up.jpg
Villa close up.jpg
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