The oldest materials of Formentera are from the Late Miocene period, specifically from 11 to 7 Ma.
During this period great coral reefs were formed that typically grew around the pre-existing reliefs arising during the Alpine Orogeny. In Formentera, although these reliefs do not rise above the surface, the fossil reefs do so extensively, Cap de Barbaria being one of the best areas to observe them.
Representative diagram of the coral reef environment that later has given way to the cliffs of Cap de Barbaria.
The cliffs of Cap de Barbaria comprise, in a large part, layers of coral colony structures that grew in successive generations during the life of the reef.
These reefs have become subaerially exposed due to a system of faults travelling ESE-WNW causing the elevation of the Promontory of Cap de Barbaria above the flatter part of the rest of the Promontory.
Cap de Barbaria lighthouse on top of the Late Miocene cliffs.
As is normal in these ecosystems, there is a great diversity of marine species, molluscs (bivalves and gastropods) being typical, as their shell tends to fossilize easily. However, at Cap de Barbaria these fossils almost always appear as internal moulds, a very common preservation of the coral beds of the Balearic Islands.
This is because the original calcium carbonate shell dissolves after the sediment has hardened and thus the part that was inside the shell is preserved.
Accumulation of gastropod fossils.
Other fossils found in the area are calcareous algae and sea urchins, together representing a shallow water environment that is laterally replaced by a set of coastal and continental deposits that emerge in the north of the described sector.
