Sierra Madre Occidental facts for kids
Quick facts for kids Sierra Madre Occidental |
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| Highest point | |
| Peak | Cerro Gordo |
| Elevation | 10,863 ft (3,311 m) |
| Dimensions | |
| Length | 932 mi (1,500 km) NW × SE |
| Width | 150 mi (240 km) W × E |
| Geography | |
| Country | Mexico |
| State | Sonora, Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes |
| Region | Northwestern Mexico |
The Sierra Madre Occidental is a huge mountain range system in northwestern and western Mexico. It stretches alongside the Gulf of California and the Pacific Ocean. This giant wall of mountains belongs to the American Cordillera, which is a vast chain of peaks running through the Americas.
High mountain peaks and giant river valleys shape this awesome region. Cool pine woods and oak trees thrive on the high lands. Down below, dry desert plains stretch out for miles. Rivers flowing from the peaks give fresh water to towns and farms. Native groups, like the Tarahumara, have lived in these canyons for centuries.
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Meaning of the Name Sierra Madre Occidental
The words come from the Spanish language. In Spanish, sierra madre means "mother mountain range". The word occidental means "western". Putting it together gives us the "Western Mother Mountain Range".
Across Mexico to the east stands another big mountain wall. It is called the Sierra Madre Oriental, which means "Eastern Mother Mountain Range". It runs along eastern Mexico near the Gulf of Mexico. Between these two giant mountain chains sits the high and wide Mexican Plateau.
The Sierra Madre Occidental starts in northern Sonora near Arizona along the Mexico–U.S. border. It stretches all the way southeast to meet the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur.
Geography and Amazing Landscapes of the Range
The mountain system runs northwest to southeast across northwestern Mexico. Giant rushing rivers have carved massive canyon networks into the western slopes. The famous Copper Canyon system is even bigger and deeper than parts of the Grand Canyon.
Where Are These Mountains Located?
These peaks run parallel to the sunny Pacific coast. They stretch across 1,250 km (780 mi) of land. The range covers parts of Sonora, Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes, and Guanajuato.
At its northern end, the chain sits about 300 km (190 mi) inland from the sea. As it moves south, it gets much closer to the coast. Near the southern end, the mountains are within 50 km (31 mi) of the salty waves.
Scientists consider these peaks part of the enormous American cordillera. This giant spine of mountains reaches from Alaska down through the western parts of North America.
Exploring the Mountain Regions and Tallest Peaks
The northern part of the mountains is called the Sierra Tarahumara. It takes its name from the local Tarahumara people. This high volcanic plateau stands at an average elevation of 2,250 m (7,380 ft). Rushing mountain water has worn deep gorges into the rock over millions of years.
The tallest peaks in the entire range rise in this northern Tarahumara zone. Measuring these remote, wild mountains can be tricky for mapmakers. The highest point is likely Cerro Mohinora. Its height is estimated between 3,040 m (9,970 ft) and 3,300 m (10,800 ft). Another peak called Cerro Barajas might also reach around 3,300 m (10,800 ft). Cerro Gordo is another giant peak reaching around 3,340 m (10,960 ft).
In the south, the mountains are known as the Sierra Huichola. Here, the range meets the rugged Basin and Range Province. Several smaller subranges branch off here, including the Sierra Pajaritos, the Sierra los Huicholes, the Sierra de Morones, and the Sierra Fría.
Rivers, Waterfalls, and Water Supply
These tall mountains act like giant rain catchers in a very dry land. Cool peaks force clouds to drop rain, creating an important source of water. Rushing rivers flow down to provide irrigation for crops grown in the valleys.
In the dry north, the Yaqui River carries vital water through Sonora into the Gulf of California. Other big rivers flowing to the sea include the Fuerte River and the Humaya River. Further south, the huge Río Grande de Santiago drains over 100,000 km2 (39,000 sq mi) of land.
On the eastern side, rivers like the Nazas River and Aguanaval River flow toward an inland dry basin. Up north, the long Conchos River joins up with the famous Rio Grande.
People have built huge barriers along these waterways to store water. A large dam creates a reservoir that supplies farms with water. The Yaqui River has three big reservoirs. On the Santiago River, engineers built the Aguamilpa Dam and the El Cajón Dam. These dams help farmers, but they also change natural river habitats. Stopping natural floods can cause soil depletion, while cutting down trees causes erosion on steep hills.
Mountain Towns and Travel Routes
Many small villages and farms sit tucked inside the giant canyon walls. Creel, Chihuahua is an important mountain town with about 5,000 residents. It serves as an active stop along the scenic mountain railroad. Further south sits the logging town of El Salto, Durango, and down near the coast lies Copala, Sinaloa.
Indigenous groups live in towns like Jesús María, while others live in Huajimic. In the Bolaños River valley, historic mining settlements like San Martín de Bolaños have thrived for centuries.
Traveling across these rugged, rocky mountains takes a lot of time. Few paved roads cross the steep cliffs. In the north, Mexico Federal Highway 16 connects Hermosillo with Chihuahua. Farther south, highway 40 winds across dramatic peaks to connect Durango and the coastal city of Mazatlán. Builders have also worked on the La Entrada al Pacifico route to link Los Mochis with inland cities.
Geology and the Making of the Mountains
The Sierra Madre Occidental is a high volcanic plateau. Underneath the volcanic rock lies a thick foundation of ancient plutonic and sedimentary rock. Rivers cut deep paths through the layers, following natural breaks and folds in the stone.
Ancient Geological History
The deep basement rock formed hundreds of millions of years ago. It includes pieces of Earth's crust called accreted terranes that smashed into North America. Over time, heat and pressure created tough metamorphic rocks like slate, schist, argillite, and greywacke. Deep ancient ocean basins left behind layers of limestone, shale, turbidites, and pillow basalt.
During the age of dinosaurs, an event called the Laramide orogeny caused powerful underground magmatism. Deep pockets of magma cooled to form granite and granodiorite. Later volcanic eruptions spread out flows of andesite and rhyolite.
During the Oligocene epoch, massive supervolcanoes erupted. This huge event is known as the Mid-Tertiary ignimbrite flare-up. Glowing clouds of superheated ash and gas settled down to create thick ignimbrite sheets and tuff. Geologists have found ten giant calderas here, including three inside Copper Canyon. These volcanic ash layers are so massive that geologists compare them to rocks in Death Valley. Later eruptions during the Miocene added alkali basalt and dark mafic lava rock.
Faults and Earth Structures
Tectonic forces pulled and cracked the Earth's crust across the range. A fault is a fracture where huge blocks of rock shift. The eastern side features high, cliff-like escarpment walls overlooking deep valleys.
When blocks of land slip downward between two faults, they create deep trenches called grabens. Cracking in the crust produced normal faults and sideways lateral faults. In some places, rocks were pushed upward by a deep underground pluton.
Valuable Minerals in the Rocks
The ancient volcanic and hot-water activity created rich ore deposits. These underground mineral veins hold lots of valuable gold and silver. For hundreds of years, miners have dug deep shafts to collect these precious metals.
The mountains also hold useful stores of copper, lead, and zinc. Other deposits include tin found inside cassiterite, along with iron, manganese, and molybdenum. In Durango, rich iron occurs in the form of black magnetite lava flows and red hematite layers.
Mountain Soils
Rich organic material covers deep layers of heavy clay across the highlands. A common dark, fertile soil found here is called phaeozems. Another type is cambisols, which provides good water drainage. On rocky cliff tops, very thin and stony soils called lithosols appear.
Heavy rains at high elevations wash minerals downward through a process called leaching. When trees are removed, bare dirt washes away easily. Protecting natural plant cover prevents serious problems like soil degradation and dangerous land slides.
Weather and Mountain Climate
Weather changes greatly from the cold snowy mountain tops down to the hot canyon floors. Because the mountain chain is so long, weather in the north is quite different from the south. Moisture arrives from both the Pacific Ocean and the warm Gulf of Mexico.
Temperature, Air Pressure, and Winds
During the winter months, an area of high pressure area sits over the mountains, bringing cool, quiet days. As summer approaches, this high pressure shifts north toward New Mexico. This seasonal change is connected to the famous Bermuda High weather system.
Mountain air stays pleasantly mild in the summer. July daytime highs reach around 31 °C, with average temperatures near 16 °C. Up on high peaks, freezing temperatures bring winter snowfall. When summer arrives, warm breezes blow in from the ocean, creating a pleasant onshore flow. As warm air rises up the mountain slopes, it forms towering clouds that bring crackling lightning storms.
Seasonal Rains and Moisture
Rainfall changes dramatically between the seasons. A wet summer monsoon brings heavy rainfall starting around June. Moist air blowing in from the Gulf of Mexico fuels afternoon thunderstorms. On the western slopes, monthly rainfall can reach over 300 mm (12 in).
In winter, weather can change depending on the El Niño-Southern Oscillation. An El Niño pattern brings wetter conditions to the northern mountains. The winter wet spell is separated from the summer monsoon by dry spring and autumn months.
Air moisture also changes throughout the day. High humidity often blankets the mountain tops at dawn with thick fog. As the morning sun warms the rocky slopes, clouds lift and the air dries out. High peaks often have a much higher dew point than the desert plains down below.
Amazing Wildlife and Natural Plants
The mountains form a cool island of life surrounded by dry plains. The famous Sierra Madre Occidental pine-oak forests grow between 1,500–3,000 m (4,900–9,800 ft) above sea level. This special place has remarkable biodiversity and shelters many endemic species that live nowhere else.
Plant Life from Lowlands to High Peaks
Plant communities change as you climb higher up the rocky slopes. Along lower slopes around 1,000 m (3,300 ft), sturdy oak trees form open woodland areas. Shady valleys on the western slopes shelter misty cloud forest habitats.
As you hike higher, tall pine trees mix in with the oaks. Near the top of the mountains, cold-hardy coniferous trees take over. These mixed conifer forests feature evergreen pines and fir trees. Some flat mountain summits are covered in natural open grasslands.
Plants time their growth around the summer monsoon rains. Many shrubs burst into bloom right before the rainy season arrives. Soon after the rains begin, plants produce juicy fruit and release their seeds. In damp valleys, trees stay green all year round.
Wild Animals of the Canyons and Forests
These mountains serve as an essential wildlife highway for animals traveling north and south. Predators like the mountain lion and the bobcat hunt in the rocky cliffs. Smaller hunters include the coyote, the gray fox, and the American badger. Secretive jaguars and spotted ocelots also roam the dense canyons.
Many plant-eating mammals live in the woods. Families of white tailed deer, large mule deer, and pig-like collared peccary herds feed on roots and acorns. Playful ring-tailed cats, white-nosed coatis, raccoons, and striped hooded skunks forage in the forest undergrowth. Small animals include the eastern cottontail, cliff chipmunk, rock squirrel, Mexican fox squirrel, and many species of the Cricetidae family of mice and rats. Flying through the night sky are dozens of types of bats.
Reptiles and amphibians thrive in the varied landscape. The aquatic Tarahumara frog lives along fast-running mountain streams. Colorful snakes, such as the Sonoran mountain kingsnake, slide through the rocky hillsides.
Birds love these pine-covered peaks. Migrating flocks use the western slopes as a safe migratory path to reach their winter homes. Rare species found here include the bright green thick-billed parrot, the crested eared quetzal, the colorful red warbler, and the loud tufted jay. The giant imperial woodpecker once lived in these old forests, but it may now be extinct. Down in the clear mountain rivers swim rare native species of trout.
Surrounding Habitats
The lower edges of the mountains blend into completely different landscapes. To the northwest lies the arid Sonoran Desert, while the dry Chihuahuan Desert stretches along the eastern side. Toward the south, dry shrublands called the Central Mexican matorral and Meseta Central matorral take over.
The warm foothills feature dense Sinaloan dry forests and tropical deciduous forest. Trees here, like the aromatic Bursera and various legume plants, drop their leaves during the dry months. Open transition zones are called savannas.
Protecting Mountain Nature
Dedicated people work hard to protect these magnificent mountains. Conservationists like Edwin Bustillos worked to save wild habitats and support local communities. Groups like Conservation International help protect rare forest wildlife.
Mexico has created several beautiful national parks in the range. Basaseachic Falls National Park features the second-tallest waterfall in Mexico. Another park is Cumbres de Majalca National Park, known for its giant, naturally sculpted rock pillars. Other large wild refuges include La Michilía, Tutuaca, and the Campo Verde Flora and Fauna Protection Area. The massive Cuenca Alimentadora del Distrito Nacional de Riego 043 Estado de Nayarit protects essential mountain watersheds and forests.
People and Rich Cultural History
People have called these rugged mountains home for thousands of years. Indigenous nations speaking Uto-Aztecan languages include the Tarahumara, the Huichol, the Cora people, and the Tepehuan people.
Ancient Peoples and Early Farmers
Ancient hunters and gatherers during the Archaic period left behind stone tools in the canyons. Around the first century AD, early farmers of the Chalchihuites culture began cultivating corn and beans on small farms. They developed better farming methods and built larger settlements until their culture declined in the ninth century.
In the northern foothills, builders from the Mogollon culture built villages between 900 and 1100 AD. Along riverbanks, later people of the Rio Sonora culture built pottery and lived inside round pit houses. Around 1200 AD, they began constructing stone and mud homes on the ground surface.
The Spanish Colonial Era
In 1554, Spanish explorer Francisco de Ibarra arrived to explore the region. European miners quickly flocked to the mountains when rich silver ore was discovered at Santa Barbara in 1567. Spanish missionaries arrived to convert the local native people.
Local native groups fought hard to keep their ancestral lands and traditions. In 1616, the major Tepehuán Revolt broke out, lasting two years. Other conflicts arose when European diseases like smallpox spread into the mountains. In 1631, miners found huge silver deposits at Parral. Catholic Jesuits ran mountain missions until the Spanish king ordered them expelled in 1767. Spanish leader José de Gálvez later reformed mining laws, triggering a major mining boom in the 1770s.
Modern History and the Mexican Revolution
Famous leaders found safety in the deep, maze-like canyons of the Sierra Madre. In the 1880s, the Apache leader Geronimo and his warriors moved into these mountains. American General George Crook traveled into the range in 1883 to meet with Geronimo. Years later, Mexican folk hero Pancho Villa used the rugged mountain trails to hide from pursuers.
During the late 1800s, engineers built new railroads to carry ore from mountain mines. Loggers arrived to harvest timber from the high pine forests. In the 1910 Mexican Revolution, mountain fighters joined the struggle across northern Mexico.
In 1961, builders completed the famous Ferrocarril Chihuahua al Pacifico railroad, also known as "El Chepe". This railroad crosses daring bridges and winds through dozens of tunnels along the cliffs of Copper Canyon. Today, travelers from all over the world ride the train to see the breathtaking beauty of the Sierra Madre Occidental.
See Also
In Spanish: Sierra Madre Occidental para niños
- List of birds of the Sierra Madre Occidental
- Sierra Madre
- Sierra Madre Occidental pine-oak forests
- Sierra Madre Oriental
