GEOCACHING POINT
GC8RN61-#4 PR3-MAC - SOS4 - MEIOS TERRESTRES
POINT 1: 39.605863, -7.933127
This geosite features a succession of Silurian lithologies (Vale da Ursa Formation), where the layers are arranged one on top of the other, but very close to the horizontal.
At the base of the sequence, there are massive metasilt-pelitic strata with a spheroidal shape, interspersed with layers of schist. This succession passes vertically into a regressive sequence, which begins with alternating layers of schist and quartzite and ends with thick quartzite benches. The outcrops of the described succession contain numerous discontinuities, from vertical to horizontal, as a result of the accumulated stresses in the rock masses. It is through these discontinuities that rainwater begins to flow, altering and disintegrating first the layers of schist and then the thinner quartzite beds.
Given the organization already described, the disintegration of the lithologies begins from the bottom up, since it is easier to alter the thin strata of schist and quartzite found at the base of the sequence than the thick quartzite beds that occur at the top.
In the early stages of alteration, preferential zones for deep water drainage developed, gradually widening towards the surface of the rock mass. As they grow and reach the surface, however, the quartzite zones are not easily disintegrated due to their vertical thickness, creating arches under which water drains. At a later stage of evolution, the arches eventually collapse as a result of the load limit of the quartzite benches being exceeded in relation to those supporting them, producing a rapid collapse.
The modeling of the landscape continues to this day, where two well-marked water lines can be observed, wider in depth than near the surface, and fragments of quartzite in their bed, a consequence of their collapse.
POINT 2: 39.607130, -7.935623
Sandy benches characterized by their white color, micaceous composition, and disorganized structure. They are usually massive with faint or even absent traces of stratification. Associated with these benches are synsedimentary folds, slumps, and water escape structures.
These disorganized benches are restricted to strata located at the bottom of a regressive succession, integrated into the Vale da Ursa Formation, from the Silurian period. They have been interpreted as the result of mass fluidized transport, as a consequence of the rapid melting of glaciers.
In terms of native flora, on the Carvoeiro route you can find a rare Azereiros forest, a tree dating back to the time of the laurel forests in Europe.
Other species such as willow, myrtle, purple heather, Lusitanian heather, alder and cork oak can appear on the way. On the banks of the streams you can find the giant royal fern which, when in favourable conditions, reaches heights of 2 to 3 metres. In these mountain streams we can find the Iberian frog, an endemic species from the northwest of the Iberian Peninsula. In this area you can find the 3 species of woodpecker that exist in Portugal. The green pectoral, the lesser spotted woodpecker and the greater spotted woodpecker. We can also be surprised by the rare black stork or by more common species like the blackheaded warbler. With luck, you may also spot animals such as the doe, the squirrel or the lonely bluebird on top of a rock.
There is a diverse geology with the presence of the Aziral folds and the sedimentary structures in Balancho ball. These structures have been related to the movement of glaciers, when this region was located near the South Pole! The Fraga dos Degolados also stands out, when all this region would be located in the southern hemisphere of the Earth.V