Geography of the archipelagos
The autonomous community of the Balearic Islands is geographically made up of a group of islands divided into two distinct archipelagos: Majorca and Minorca make up the archipelago of Gymnesia ("Great Balearic Islands"), while Ibiza and Formentera together form the archipelago of Pitiüses (“Little Balearic Islands”), which in Catalan means “covered with pines”, in reference to the primitive pine forests that cover their territories. The four main Balearic Islands, Mallorca, Menorca, Ibiza and Formentera have a total area of almost 5,000 km².
The largest island in the community, Majorca measures 100 km from east to west and 80 km from north to south for an area of 3,640 km². It is the island that has the greatest variety of landscapes, with sandy and rocky coasts, but above all two mountainous cordilleras whose peaks climb, for the Serra de Tramuntana, to more than 1,400 m, with the highest point as the aptly named Puig Major (1,445 m). Between the two sierras, there is a vast depression where the main, but modest, agglomerations of the island are located. The rest of the space is dedicated to agriculture and especially to arboriculture (orange trees, lemon trees, fig trees, etc.). The other large island of the northern archipelago, Menorca (695 km²), is almost six times smaller than its imposing neighbour, but nevertheless remains the second island by area of the autonomous community. About 48 km long and reaching 20 km at its widest point, it is extremely windy and crossed by low walls which give it its charm. With a modest vegetation cover, Menorca is dominated by a summit, also modest, Monte Toro, which culminates at 357 m. The island has two large agglomerations, Maó to the east and Ciutadella to the west, which account for two thirds of the population. Surrounding Mallorca and Menorca is a scattering of small islands, the largest of which are Sa Dragonera and Cabrera, to the west and south of Mallorca respectively.
The second archipelago of the autonomous community is that of the Pitiüses or Pityusas, composed mainly of the islands of Ibiza and Formentera. Ibiza is, by area, the third island of the Balearic Islands with 570 km². 40 km long and 20 km wide, it is extremely mountainous and still covered, in some places, with a primitive forest of pines, the trees that gave their name to the archipelago. There are rare plains, dominated by Mount Sa Talaiassa, 475 m high. The other mountainous massifs, mainly composed of limestone rock dating from the Cretaceous, are those of the Serra dels Mussols climbing to 347 m, the Serra Grossa and its 398 meters of altitude and the Mala Costa reaching 410 meters high. Ibiza is attached to its neighbor Formentera by a series of rocks and islets. The two islands are separated by a 3 km strait dotted with islets, classified as a nature reserve (the strait of Es Freus). It is the second most important marine reserve in Spain, named Ses Salines Natural Park. It is renowned for the richness of its seabed, where Posidonia meadows flourish, listed as a UNESCO heritage site since 1999. Formentera (83 km² and 69 km of coastline) resembles, in its shape, Guadeloupe and is known as the smallest island in the Balearic Islands, but it is also the flattest and driest. It is made up of two very distinct parts, one very flat to the west, and the other mountainous to the east, dominated by the 192 meters of Puig La Mola, the highest point of the island. The two ends of Formentera are connected by a narrow strip of land lined with beaches. To the south of the island, Cape Barbaria forms an arid semi-desert promontory dominated by a lighthouse serving as a landmark for ships entering the Mediterranean Sea through the Strait of Gibraltar, as for the east, the Mola plateau reveals windswept rural landscapes that culminate in steep cliffs. The east coast is also cut by several points, from Punta de sa Creu in the north to Punta Roja in the south.
The posidonia herbarium: treasure of the seabed
A pure treasure of the seabed, Posidonia oceanica is not an algae, but a flowering plant which, almost 100 million years ago, adapted from the land environment to the ocean environment. Endemisms of the Mediterranean, they form what are called “meadows” or “herbariums” of Posidonia. Considered true “ecosystem engineers”, they play an essential ecological role within the Mediterranean coast. If they cover a good part of the Mediterranean, the Posidonia meadows which are concentrated in the Ses Salines Nature Reserve, between Ibiza and Formentera, are among the best preserved.
The plant consists of roots buried in sediment and erect stems, both called rhizomes. These are real nutrient reserves! The upright rhizomes produce scale-like leaves all year round. These leaves serve as a refuge for many animal and plant species that find a natural habitat in these herbaria. When they fall, the leaves produce a large mass of plant matter necessary to feed a large number of animal species: carried by the current, they serve as food for sea urchins and crustaceans, certain fish, but also sea turtles. It is in autumn that the flowering of the plant begins (which does not necessarily flower every year, it depends on the temperature of the water), which then gives a sometimes very dark fruit, visually close to the olive. , after about eight months of maturation, earning it the nickname in some corners of the Mediterranean of "sea olive".
An important source of oxygen. A veritable "lung of the sea", Posidonia oceanica is a major source of water oxygenation, favorable to the biodiversity of its ecosystem. It is said that a square meter of posidonia produces more oxygen than a square meter of Amazonian forest! It also plays a role of purification by "trapping" the sediments present in the water in the form of fine particles. Stored in what is called “the matte”, the sediments contribute to the growth of the Posidonia rhizomes. It is thanks to this mechanism that the plant in turn contributes to the transparency of the water. In addition, the presence of Posidonia meadows slows hydrodynamics, and therefore limits the presence of particle suspensions in the water, favored by the various marine currents.
A protected species. For many years, Posidonia meadows have been in decline. The development of construction along the coasts, the dumping of harmful chemical substances into the sea and uncontrolled fishing in sensitive areas have long favored the regression of this natural regulator of the Mediterranean seabed. The Posidonia meadows are now protected, as is the case for the meadows that flourish off the coast of Ibiza and Formentera: the Ses Salines reserve was thus classified as a UNESCO heritage site in 1999. Posidonia is today the subject of special monitoring because of its precious ecological virtues, throughout the Mediterranean basin.