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The Andes Mountains - a case study of how Fold mountains are used

About the Andes Mountains

The Andes Mountains run the length of the West Coast of South America, rising in the North in Colombia and finishing in Chile and Argentina in the South.   They are world's longest mountain range running for over 7,000km and covering 6 countries. 

The mountains have been formed as a result of the convergence of the Nazca plate and the South American plate.  The heavier oceanic crust of the Nazca plate is pushed towards the South American plate, and because it is denser is subducted underneath.  The South American plate is less dense so sits on top of this subduction zone, but the rocks of the South American plate have been folded upwards and crumpled into fold mountains.  There are also Volcanoes and earthquakes along this destructive plate boundary - earthquakes caused by stresses building up as the 2 plates try to move past one another, and volcanoes caused by magma working its way up through vents in the Earth's crust.  This has created a sequence of volcanoes and fold mountains, rising up to 6962m at Aconcagua.  The trench (marking the boundary between the Nazca and South American plates) to the West of the Andes mountains is called the Peru-Chile Trench, and reaches an incredible depth of 8066m under the sea level.

These areas are very hard to live in because of the physical geography.  The relief is very steep making farming difficult, and the high altitude makes breathing difficult.  The mountainous terrain make it difficult to construct roads and railways to allow for communications.

How the Andes Mountains are used

A map of the Andes mountains


Find out More

Complete the chart on this sheet using the website links below:

Wikipedia article on Yanacocha gold mine

BBC article on the Yanacocha Gold mine

Info about a mercury spill at the Yanacocha mine

No Dirty gold website about Yanacocha

Background to the Yuncan HEP plant

Protest over the Yuncan HEP plant

Some information about the pros and cons of dams (just look at the 2 tables)

Information on responsible tourism in Peru

The pros and cons of tourism to Machu Picchu

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   Farming in the Urubamba valley

 

Farming

The mountain slopes of the Andes are used for a variety of farming practises.  The best land can be found on the valley floors, but an ingenious system of terraces dug into the valley sides and held up by retaining walls has been used to bring the lands on the valley sides into food production.  The flat terraces help to hold up water in a region where there are marked shortages. Most crops are grown in the lower areas and include soya, maize, rice and cotton. However, the main staple crop of the Andes is the potato, and there are hundreds of different varieties found in the mountains.

Most farming is subsistence, with the food grown for personal consumption, but there is some commercial farming.

Llamas have historically been used a lot in the Andes, as a form of transportation and to carry goods.  Alpaca, a relative of the Llama, has been used to produce some of the finest cloth known to man, and is also produced in the Andes mountains.

Mining

The Andes mountains contains a rich mix of minable materials that are both very valuable and very useful to man.  When the Spanish conquered South America their prime objective was to prospect for gold.  Potosi in Bolivia was one of Spain's principle mines and produced lots of silver. There exist large deposits of Coal, oil and natural gas, iron ore, gold, silver, tin, copper, phosphates and nitrates and Bauxite (for aluminium) within the Andes mountains.  The Yanacocha gold mine in Peru is the largest gold mine in the world.  It is an open cast mine and the rocks containing the gold are blasted with dynamite.  The rock is then sprayed with toxic cyanide and the gold extracted from the resulting solution.  This can contaminate water supplies.  The nearby town of Cajamarca has grown from 30,000 when the mine started to 240,000 people in 2005.

The gold mine at Yanacocha
The Yuncan dam

Hydroelectric power

The deep valley and rivers of the Andes give it huge potential as a region to produce hydroelectric power.  The narrow valleys are ideal to dam as it cuts costs, and the steep relief increases water velocities allowing electricity generation.  Snow melt fuels most of the water provision, but this means that HEP production can be reduced to small amounts in winter.  The Yuncan dam project dams the Puacartambo and Huachon rivers in northeast Peru, while the el Platinal project will begin construction in 2009.

Tourism

Tourism is a massive industry for Peru and the country has a lot to offer.  In the East you can take part in Eco-tourism activities in the Amazon Basin, as found along the Madre De Dios River near to Puerto Maldonado.  Peru has some fantastic coastline as well, but the highlight of Peru is undoubtedly the Inca Trail. You can take a virtual field trip of the Inca Trail here.  The trail basically covers 43km of old pathways linking together old Inca settlements in the inhospitable mountains of the Andes.  It is South America's best known trek and is one of only 23 World Heritage Sites (as deemed by UNESCO) to be classified as important both naturally and culturally.  The trail is covered in 4 days and covers around 43km, and finishes with sunrise at the "Lost City of the Incas" at Machu Picchu.  The trail is strictly controlled, and only 500 trekkers are allowed to start out on the trail every day.

Machu Picchu
 
Some images of the Andes mountains

A short video inside the Yanacocha gold mine