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.
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.
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