The Andes

The Andes Mountain range is a fascinating site on the geologic map. The way it snakes from the top of the South American continent starting in Venezuela and continuing to Cape Horn, Chile. It actually continues out past the continent forming an underwater mountain range and forming many islands. The highest mountain is Mount Aconcagua located along the Chile and Argentina border. It is 22,834 feet high and the highest mountain in the Western hemisphere. The Andes run along the continent for 5,500 miles through Venezuela, Columbia, Ecuador, Peru, Bolivia, Chile, and Argentina. The mineral deposits in the mountains have shaped the history and culture of the continent and the world.

About 450 to 250 million years ago, eroded sediments from an ancient granitic continental fragment in present day Brazil were deposited on the western side of the continent. The weight of these deposits over the millions of years eventually weighted down the western side. This forced a subsidence of the crust, and the pressure and heat metamorphised the sediment deposits like sandstone, limestone, and siltstone into a more resistant metamorphic rock like quartzite, shale, and marble. Then 170 million years ago, the Nazca oceanic plate collided with the western side of the continental South American Plate. The heavier oceanic plate sub-ducted under the continental plate. This gave rise to mountain building activity along with magma intrusion from the mantle. The period of rise started about 25 million years ago and continues today. There is considerable volcanic activity which is part of the Circum-Pacific “Ring of Fire”. Earth quakes are also common along the mountain range.

The Andes can be divided up into the Southern, Central, and Northern Andes. The South section starts with the Fuegian Andes at Staten Island through Grand Island. Next is the Patagonian Andes which is where I wish to live for about a year in the near future. It starts at the Strait of Magellan and continues to the North Lake of Alumine in Argentina. This section is full of ice fields, glaciers, rivers (kayaking?), lakes and fjords. It is a grown-up’s playground. Thankfully, Argentina and Chile have created national parks to preserve the beauty of this patagonia area. The Central Andes begin here and traverse into Southern Ecuador. This section is very different compared to  the Southern section. It is wider, arid, and higher with difficult passes. Mount Aconocagua is located here along with many other high mountains that include Mount Tupugatu at 21,555 feet and Mount Mercedario at 22,211 feet tall. Here also starts the high plateau region called the Atacama Plateau. The Atacama Desert is located on the western side along the coast. The Northern section starts with the Ecuadorian Andes which is made up of a long narrow plateau from the north to the south and bordered by many volcanoes. In the west, there are nineteen volcanoes and seven of these exceed 15,000 feet tall. In the east, there are twenty volcanoes with Chimbrazu being the tallest and having a permanent snowcap. The Venezualan Andes continues and ends the range in the city of Barquisimeto. Much erosion has exposed granite and gneiss rocks, but there is still much fertile land for agricultural needs.

Reference: Encyclopedia Britannica

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