Shifting the Landscape

Home to many indigenous people, the Sierra Madre del Sur mountain range runs along the coast of Oaxaca and is one of three main mountain ranges found in the state.  Due to its location on the border of the North American and Cocos tectonic plates, we are lead to believe that it formed through an oceanic and continental crust convergence.  Upon collision, the denser composition of the oceanic crust of the Cocos plate caused it to subduct beneath the less dense continental crust of the North American plate.  The friction from this interaction created extreme heat, and along with tremendous pressure, melted the oceanic crust and lithosphere, which eventually cooled, moved to the surface, and created the Sierra Madre del Sur.

    

Oceanic - Continental Convergence

Tectonic plate map displaying the
 subduction zone along the Mexican coast

This image of the Sierra Madre del Sur exhibits a fault line
and scarp due to extension faulting

At the base of the Sierra Madre del Sur, La Punta del Cometa overlooks the Pacific Ocean.  This rock formation exhibits the distinct layers of clastic sedimentary strata, which is formed by the compaction of eroded and weathered rock sediments. 

La Punta del Cometa
In the center of this picture, a possible fault line can be seen.
Hypothetically the lighter, felsic metamorphic or igneous
rock was uplifted in compression, creating a reverse fault. 

Not only do these geographical landmarks serve as tourist destinations, the mountains of the Sierra Madre del Sur are also home to many small scale farmers.  While some grow native produce such as coffee and sugar cane, the high demand of drugs from cartels persuades many farmers to grow opium and marijuana.  The seclusion and vastness of the landscape of the Oaxacan mountains provide farmers with a safe place to cultivate the poppy plant, which cannot thrive below 1000 meters. With elevations ranging from 1500 - 3500 meters, the poppy plant can grow in abundance anywhere in the mountain range. While this is monetarily beneficial to the farmers, it has a devastating impact on the civilians of Mexico who are suffering from decreased food supply and tourism, and increased violence and drug use (Humphrey, 2003).

References

Humphrey, C. (2003). Narcotics, Economics, and Poverty in the Southern States. Retrieved from http://lse.academia.edu/ChrisHumphrey/Papers/292223/Narcotics_Economics_and_Poverty_in_the_Southern_States