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NATURAL LANDSCAPE
/The geological substratum and reliefs
The geological materials that compose the Tramuntana area cover a period spanning the end of the Palaeozoic Era (Carboniferous Period) and the lower Miocene, that is to say a period of time of between 240 and 15 million years. In general, the mountain range is made up of sedimentary rocks, predominantly Jurassic limestone (Secondary era), which give rise to the characteristic greyish colour of the range´s summits and cliffs.
These rocks are formed by sedimentation occurring at the bottom of former sea basins that were subsequently – around 15 million years ago – affected by what is known as the Alpine orogeny. This was a long mountain-formation process that took place as a result of the collision of the African and European continents, causing the slow folding of big marine sedimentary rock masses that now constitute the Mediterranean´s most important mountain ranges, such as the Atlas Mountains, Baetic Mountains, Alps or Pyrenees.
The rocks that today compose the Tramuntana Mountains were therefore subjected to a process of compression in a north-westerly direction. This gave rise to the range´s successive folds and thrusts, aligned in a north-easterly/south-westerly direction and stacked towards the northwest. Consequently the northern face of the range has more energetic reliefs, corresponding in general terms to the thrust fronts, whilst the southern face is gentler in relative terms, since it adapts to the general southeast inclination of its rocky materials.
Another characteristic of the reliefs of the Tramuntana Mountains is the alternation of large cliffs and summits with valleys and faces that are not so steep, due fundamentally to lithological differences: the cliffs and massifs are formed by the hardest limestone rocks, whilst much softer materials have settled at the base, such as clays or calcarenites – materials characteristic of mountain slopes and valley bottoms. This alternance of hard and clayish materials is also important because it explains the emergence of water in the form of numerous springs and sources.
This general north-easterly/south-westerly layout of its reliefs is interrupted by perpendicular cuts caused by faults that occurred during the aforementioned orogeny, but also as a consequence of the expansion process that took place after it had concluded. This is how the valleys of Valldemossa, Puigpunyent or Sóller appeared. At other points, these fracture lines are places where large karstic canyons and gullies have formed, due to the physical disintegration and chemical dissolving of the limestone rocks.
On this mainly limestone lithological base, there is an immediate succession of erosive processes that give rise to a distinctive geomorphology, since they cause the rupture, transportation and sedimentation of rocks. In the Tramuntana Mountains four main modelling typologies can be observed: a fluvio-torrential system, associated with gullies and torrents, a facial system in the form of cliffs and slopes, a coastal system, typical of the coastal area, presenting morphologies such as coastal cliffs and coves, and a karstic modelling system, the result of the chemical action of water dissolving limestone rock: an essential factor in the landscape´s singular features.
The fluvio-torrential system is extremely well represented in the Tramuntana area, through the presence of an extensive network of torrents, gullies, streams, torrent beds and streambeds. In Mallorca, the concept of a torrent is used to refer to a short watercourse where water flows intermittently or temporarily along a fixed channel. Its main characteristic is that it is episodic, and may dry out for part of the year. In general terms, the fluvio-torrential system makes use of soft materials found on the base of the limestone massifs to create broad longitudinal valleys through which the network of torrents is organized. Even so, it is frequent in headwater areas to find torrents carved out of limestone packets, taking advantage of structural fractures or weaknesses, creating deep cuts in the rock and turning into spectacularly-shaped karstic canyons.
The watercourses in the Tramuntana Mountains – torrents, as they are called locally – are for the most part positioned longitudinally, following the direction of their geological structure, although they are also often positioned in short crosswise sections that carve out gullies and small canyons (so-called estrets), such as those of the Ternelles valley, Cúber plain, connection between the Orient valley and central plain of Mallorca via Es Freu and Coanegra, and the emblematic Valldemossa strait. The coastal face is made up of extremely steep, brief streams and torrents that descend almost directly from the line of summits down to the sea.
The modelling of the facial system encompasses a wide range of processes and forms caused by the action of meteorization processes on the slopes and peaks of rocky mountains. Modelling processes related to large falling boulders are well represented in the mountain range, as is the slow dismembering of slopes, forming small or large areas of scree, due to the accumulation of boulders that have come loose from the sides of the mountains.
Thirdly, the coast is a highly dynamic environment in which modelling takes place by means of mechanical processes (abrasion caused by wave movement) and bio-erosive processes caused by the organisms typical of these environments.
Nonetheless, the most interesting system and landscape in geomorphological terms in the Tramuntana area is the karstic system. It is an erosive system typical of carbonate rocks (as indeed limestone rocks are), composed for the most part of calcium carbonate. They are attacked chemically by water in the presence of carbon dioxide, in a process known as karstification. These rocks give rise to a wide variety of morphologies both on their exterior (exokarst) and on their interior (endokarst, which forms underground galleries, caves and chasms).
In the Tramuntana area, the exokarst is apparent in the form of external morphologies such as sink holes, karren fields and karstic canyons. The Torrente de Pareis, in the municipality of Escorca, is an excellent example of this latter morphology. Karren produces a landscape with a striated appearance, popularly known as rellar or esquetjar, words that appear repeatedly in the Tramuntana toponymy. The most spectacular shapes include those of the Ses Monges field or Es Pixarells, in the Lluc area (municipality of Escorca). Superficial karst modelling also gives rise to the presence of closed depressions – sink holes – which dissolving processes have helped form. Meanwhile, endokarstic signs are also extremely frequent in the mountain range. There is a remarkable abundance of vertical underground cavities (chasms or avencs according to popular Catalan terminology), which can reach depths of up to 100 m. You can also find typical caves, which form a complex series of cavities through which an underground water drainage system can be traced.