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The Explosive History of Praia da Luz BY LUĂ?S AZEVEDO RODRIGUES
All the multicoloured layers of Praia da Luz are pages of a book, in which each page tells us a moment of the geological history of the Algarve. 4
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The multicoloured rock sequences reveal the composition of the sedimentary rocks. Still, they also show us 120 million years of history, stories of advances (transgressions) and retreats (regressions) from the sea, a coastline that is constantly changing. The strata of fine sediments, such as marl and clay (green, red and violet tones) were deposited in environments further from the coastline. In contrast, the sandstones (yellow tones), where, for example, we can observe the Nerineas (fossil shells), and are sediments deposited near the shoreline height, in an environment similar to a beach. The cliffs of beautiful coloured layers close to which we now place our towel were once a deep seabed or a coastal area close to the continent of that time, or even a beach environment. How do we know this? We can see this from the characteristics of the rocks, for the size and types of its minerals, and its colours. If we walk east, with the sea on the right, we reach the natural limit of Praia da Luz, a dark rocky barrier, almost black in some places, that almost prevents the walk. This barrier is Ponta das Ferrarias, popularly called Rocha Negra (Black Rock). These are the remains of an ancient volcano, which was created around 70 million years ago, making it the same age as the Monchique formation, which is not volcanic. Despite not being as big or impressive as Vesuvius or Etna, we are still able to recognise part of the walls of the Luz volcano dating from the upper Cretaceous. This period of the earth's history immediately follows the famous Jurassic.
