Geo adventures at Santa Luzia, 2020
It was a cold but sunny January day back in 2020, when we decided to go climb a via Ferrata at Santa Luzia Dam near Pampilhosa da Serra. Our early arrival wasn’t in fact that early, but was really a cold day! Usually on weekends if not difficult to find rock climbing the northern side routes were already crowded (Photo Below). But on this day we were by ourselves! All alone on this amazing rock face with an amazing geo History.
To put it simple, the rocks exposed here are Ordovician in age (Arenigian to Llandeilian), i.e. were deposited 485 to 458 million years (Ma) ago, during the first part (Lower) of the Paleozoic Era.
At this time, large areas of sandy to muddy beach and shelf environments were being deposited in this region. In fact during the Lower to Middle Ordovician much of central Europe, Iberia and North Africa and America shared these same environments. These were the seas where the trilobites lived, and where it is possible today to find their fossil tracks (Cruziana ichnofossils, aka trace fossils)
For the next 100 Ma, still during the Paleozoic Era, the sands and shales were buried and gently heated, being transformed in sandstones and shales.
Later during a mountain building process called Variscan/Hercynian orogeny, at the end of the Paleozoic Era, the sandstones and shales were buried even more and folded at the same time. This led to metamorphism, i.e. changes in the composition and structure of the rock by pressure and temperature, that transformed the original beach and shelf sediments into quartzites and schist.
During this orogenic process the rocks were “squeezed”, folded and faulted, reason why nowadays the rock units, such as the quartzites in the photo, are tilted near vertical and faulted.
From then to the present day, the softer schists sequences were eroded more easily than the rigid quartzite units, leading to what is known as differential erosion. That explains the origin of the Santa Luzia.
Come with us on a Geoadventure of a lifetime❣️🌍
