Plate Boundary Essay

Plate Tectonic Essay: South America

The idea that earth used to be one giant continent seems farfetched, but due to Alfred Wegener and Alexander du Toit theories of continental drift and sea floor spreading that idea seems more possible. Alfred Wegener was German geologist who first proposed the theory of continental drift which stated that the world was made up of one giant continent called Pangaea, which eventually separated and drifted apart forming into the seven continents we have today. According to plate tectonic theory, the earth's surface is broken into a certain number of shifting plates which moves relative to one another above a deeper and hotter zone at a average rate of a few inches per year. The South American Plate is one of Earth's tectonic plate which covers the continent of South America and extends eastward on towards the Mid Atlantic Ridge. The east side of the South American Plate is a divergent plate boundary with the African plate boundary forming the south part of the Mid Atlantic Ridge. The South side of the South American Plate boundary comes together with the Scotia Plate and the Antarctic Plate, and the west side of the South American Plate boundary is subducting with the Nazca Plate boundary.

South America's plate tectonics are responsible for the massive Andes Mountains and the massive volcanoes that go on there. The reason why is because the Farallon Plate splits into the Nazca plate and the Cocos Plate which are subducting under the western part of the South American Plate which is what lifts the Andes mountains. The eruption of the Colombian volcano Nevado del Ruiz in 1985 is an example of an event which happened in south America due to its specific plate tentonics. Nevado del Ruiz is a stratovolcano located within the pacific ring of fire, and is also part of the Andes Mountains. Nevado del Ruiz is a broad and glacier covered volcano which is composed of mainly andesitic and dacitic lavas and andesitic pyroclastics. Nevado del Ruiz's cone consists of a broad cluster of lava domes built within the summit caldera of an older Ruiz volcano. The eruption of Nevado del Ruiz in November 13, 1985 ejected materials during the eruption which melted part of the glacial ice cap at the summit of the volcano which released a series of volcanic mudflows and debris flows. The lahar swept down the valleys of the River Guali and the River Lagunillas with speeds of 445 km/hr killing over 23,000 people. The lahar flow descended from the eastern side of the volcano and devastated the city of Armero by destroying about 400 houses and causing as many as 1,800 deaths near the town of Chinchina.

South America's plate tectonics are not only responsible for massive volcanoes but also massive earthquakes as well due to its specific plate tectonics. In fact, one of the largest earthquakes ever to happen happened on May22, 1960 off the coast of south central Chile.