Tuesday, February 15, 2011

The Andes Mountains

Patagonia is a main attraction for the tourists, and a home for the locals in Argentina.  Surrounded by glaciers and volcanoes, this vast region is found in the Andes Mountains.  These mountains were formed by the process of convergence and subduction.  In these processes, ocean crust (composition of basalt) collided with continental crust (composition of granite).  As a result, the Andes mountains were thrust upwards from the oceanic and continental plate's collision.


      The Andes continue to grow as the lithosphere begins "rafting" on the asthenosphere.

                         Caption:  A aerial view shot of Patagonia taken from Chile.


Caption:  The picture above shows a fault-line scarp of a normal fault in the Andes.

This normal fault was formed by the process of extension.


The Copahue Volcano below is an active stratovolcano.  It is composed of andesite and has a composite cone with a caldera of twelve miles in diameter.  Since this volcano is near a lake, many geysers exist due to the geothermal activity.  During an eruption, this stratovolcano expels lava with high viscosity.  In the last eruption of Copahue, pyroclastics such as tephras, cinders, and bombs were emitted.  Being near the eruption, locals and tourists inhaled this dangerous ash.  With this volcano surrounded by snow, it is probable that there were lahars.


Caption Below:  The video below gives a great 360 degree view at the solfatara field of the Copahue volcano and shows numerous, basalt-lava flows and dikes.


Caption Below:  A great example of isostatic balance is shown in the glaciers near Patagonia.


            As the glacier recedes and the ice melts, the crust (lithosphere) shows isostatic rebound.           

               Below: Perito Moreno Glacier


Works Cited