Geoturism Balearic Islands

The Sedimentary rock whose main component is calcium carbonate (CaCO3). Its origin can be chemical, organic or detritic.</p><p><br></p></div>">limestone outcrops on the Binimel·là massif are characterised primarily by their tectonic and palaeontological interest as a consequence of their very well configured folds and by the presence of remains of fossils of crinoids.

Close up, we can see that the ash grey-coloured limestones display a very fine texture and are made up of small laminations that are related with filamentous cyanobacteria, which were responsible for the precipitation of the calcium carbonate particles that formed the rock. The levels generally display thicknesses of nearly 1.5 metres, but they are usually displayed in sets of layers of between 10 and 15 cm.

The highest part of the levels show fossilised plates of crinoids, of the Balearocrinus breimeri species. Crinoids are known as sea lilies due to the ramified appearance of their arms. They are considered to be the oldest group of echinoids (such as sea urchins) that exist, as they appeared over 475 million years ago. 

Crinoids are comprised of a calyx, which contains the animal’s body and from which emerge arms that serve to trap food particles, and a stem anchored to the seabed by roots. These elements are made up of calcite plates that can become fossilised. The ones on the calyx are in polygonal shapes, while those on the stem, which are both polygonal and circular, are characterised by being perforated. This species of Echinoderm equipped with a calyx in its centre, surrounded by articulated arms, covered by regularly-arranged plates. Some species also have a stalk (peduncle) which fixes them to the substrate.</p><p><br></p></div>">crinoid was described by science for the first time at this stopping point.

The sedimentation of these rocks occurs in shallow seas due to the fact that the Sedimentary rock whose main component is calcium carbonate (CaCO3). Its origin can be chemical, organic or detritic.</p><p><br></p></div>">limestone components dissolve beyond a certain depth due to the decrease in temperature and increase in pressure. In addition, it should also be remembered that the filamentous cyanobacteria responsible for the formation of the rock need light for photosynthesis. Similarly, the presence of crinoids and the absence of other fossils indicates that these organisms dominated the rock formation ambience, a seabed of calm and shallow waters. On the surface, we usually find accumulations of iron oxides, which indicate times when no sedimentation occurred.

Today, it is difficult to find fossils of the plates forming these animals as their popularity has led to fossil-hunting in the area. We should not forget that fossils are exceptional and essential elements in knowing the history of our planet and that fossil remains should never be removed indiscriminately: their place is in situ.