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1. After
walking through the gorge, is the bottom of the
strait made up of loose rocks, compact rock bottom,
or both? What is the predominant color of the rocks
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2. What is the most important
factor in the formation of straits, dissolution or
entrainment?
3. What acid is responsible for
the dissolution of limestone rock? Where does it
come from?
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Location
The Matarraña River gorge, also known as the Parrisal,
offers us highly attractive natural places and a mountainous
landscape of abrupt limestone formations. The Puertos de Tortosa
and Beceite Natural Hunting Reserve protects a large part of the
mountains, ravines, valleys and rivers of the region. They are
home to spectacular flora and fauna typical of a river
environment.
Although it does not show signs of it, the Matarraña River is one
of the Mediterranean-type river systems with the greatest
biological diversity in Europe, having cataloged more than 300
species of algae, more than 200 aquatic invertebrates, and nearly
200 vertebrates. Furthermore, it is a region with great historical
value, since in this area, near the river, we can admire some cave
paintings.
The route runs parallel to the Mataesrraña River and sometimes we
will advance along some wooden walkways anchored in the rock and
we will reach the Straits, where to continue we will have two
options: swim across a series of badinas or leave the riverbed and
use the equipped step of the Romeret, suitable for beginners. This
excursion is very popular, short and aquatic, recommended
especially in summer, when swimming is more pleasant, although it
is necessary to avoid very dry periods in which we may find the
final stretch of the Straits without water, thus losing the
excursion a good part of its charm.
Periods of heavy rain must also be avoided, in which passage
through the Straits can be very dangerous. So, the Romeret path is
an interesting alternative that allows you to overcome this
delicate step above without having to soak, only recommended for
people without vertigo.
The Parrisal marks the birth of the Matarraña River that gives its
name to the region, forming a deep canyon two hundred meters long,
sixty meters high and two meters wide. It is a relief of limestone
rock where streams and springs abound. These are large rock
faults, waterfalls and natural wells, transparent waters and
native forests. As you advance through the gorge, the canyon walls
become increasingly taller and more vertical, sometimes forming
spectacular needles.
They are the famous Gubies (grayish and orange limestone rocks,
with vertical shapes with a sawtooth appearance due to erosion).
The walls of the canyon finally come closer together, leaving a
crack about twenty meters wide and more than a hundred meters
high: the Parrisal Narrows.
Geomorfology
Formación
A gorge is a narrow, elongated opening like a gorge between the
mountains and at some remote time was the channel of water, is
also called mountain pass, throat, port, step, sickle or open,
according to dimensions that characterize it in a given region
River erosion as a determinant factor
The water of the continents often runs as rivers do on the surface
of the earth, or in the form of underground currents (or
groundwater) producing a continuous friction against sedimentary
materials and eroding them. In turn, while the water continues to
run, it drags with all the resulting residues, transports them
towards the lower areas of the relief and deposits them in
different spaces. In this way, sedimentary platforms such as river
terraces, dew point cones and other geographical features are
formed. Simultaneously, the water that flows in the fluvial
streams generates waterfalls, caves, meanders, deltas, estuaries,
and so on. All these processes as a whole end up configuring
landscapes and supplying the environment of a superior beauty.
Dissolving is easier than dragging, dissolution mechanism:
The carbonic acid that causes these formations is formed when rain
passes through the atmosphere and collects carbon dioxide (CO2),
which dissolves in water. Once the rain reaches the ground, it can
pass through the soil and provides much more CO2 to form a weak
carbonic acid solution, which dissolves the calcium carbonate from
the rock
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