Tuesday, March 12, 2013


Chile displays examples of rock weathering and erosion throughout its landscape.  The iconic archway, La Portada, is a rock form surrounded by ocean, located in Chilean territory.  The photo below provides a visual of the archway and the multiple weathering processes that have affected its appearance over the years. Mechanical weathering has occurred through waves crashing into the sides of the rock repeatedly, gradually causing small pieces of rock to fall away from the main form.  The salt within the water has aided in this physical process.  The two color tones (charcoal color close to the bottom of the form and the white on top) can indicate that the charcoal-colored rock is a weathering rind (a color change due to weathering) if in fact the white rock is the true color.  If not, the white color could be salt residue due to the large amount of salt that is present in the water when it hits the rock. 
                                                       La Portada Archway in Chilean Territory

A more hydrated region of the Atacama Desert is the National Flamenco Reservation, shown below.   As part of the O Horizon, (the outermost horizontal layer of soil on the earth’s surface), the water reserve is an ecosystem where the water can be classified as capillary water, the type of water that is essential for vegetation to grow.  There’s evidence of soil erosion in how the small peninsulas of land are reaching across the water way; the entire area pictured was once a dry surface without water.  The small land mass could be the remnant of the land that was once there.  To further this assumption, there are moderately sized white chunks of rock in the water way that suggest weathering and erosion of a larger rock form that once existed in the area.  The smaller pieces of rock in the photo could have detached through weathering and then were transported by erosion.
                                                  National Flamenco Reservation, Chile
 
References:
http://wanderingtrader.com/travel-photos/pictures-of-chile/salar-de-tara-atacama-desert-chile/

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