Mallorca's Caves and Coves

MONOGRAPH The Enchanted Cove

MALLORCA’S CAVES AND COVES THE GENETIC AND HYDROLOGICAL RELATIONSHIP BETWEEN COVES AND CAVES

FRANCESC GRÀCIA, BERNAT CLAMOR, PERE GAMUNDÍ, JOAN J. FORNÓS AND DAMIÀ VICENS

The exploration and documentation of the coastal caves in Migjorn, Mallorca –many of which have large underwater galleries– would suggest a genetic and hydrological relationship between these coves and endokarst. These caves are an essential part of Mallorca’s natural heritage.

To begin with we should point out, as Rosselló stated for these caves, which considers the formation of (2005), that if we move from the toponymic –or primordial voids, caused by dissolution in the water popular– ambit to the scientifi c one, not all coves table due to the aggressiveness of the mixture of are calas (coves) strictly speaking, nor all those fresh inland waters and marine waters within highly called so. On the one hand, authors such as Gràcia permeable rock, given signifi cant primary porosity. et al. (2011) deduced from the collapse of the roof Many of the galleries and chambers forming these of a cave forming a more or less narrow and long cavities are now located below sea level and have kind of inlet called a caló. On the other hand, many been invaded by water. It is very interesting that coastal cavities are related to seawater fl ooding of there are different levels of cavities, corresponding to varying proportions. Rosselló et al. (2002) discuss different periods of speleogenesis. The planimetric the complexity at the average pattern of caves like these would scale of the east coast of indicate the somewhat random Mallorca and southern Menorca, coalescence of more or less «COASTAL KARST CAVITIES precisely by the concurrence independent units, which have of coves and caves in Upper APPEAL TO TRAVELLERS AND grown three-dimensionally, Miocene limestone, which NATURALISTS, ESPECIALLY connecting with each other are very sensitive to karst- AFTER THE DISCOVERY OF to give rise to a branching driven evolution. The coves are THE CURRENT TOURIST formation. associated with the mouths of Besides the aforementioned ATTRACTION COVES DEL river courses, but their shapes caves resulting from marine may have been affected by DRAC» abrasion –non-karst– a type subsidence, driven by fracture of cavity abounds on the and karstic dissolution processes coast, which is the result of that have occurred at different levels. the caves being captured within the coastal mixing zone, namely, karstic processes, due to the eating away of cliffs by sea-driven mechanical erosion. ■ COASTAL NOTCHES IN MIGDIA DE MALLORCA Given the combination of processes, these caves are Notches and hollows generated by coastal erosion known as karstic-marine captures. Quite complex processes, namely caves related to marine abrasion, sedimentary deposits abound, which are interspersed abound along the coast, although they are often by speleothems (mineral deposits) with ossiferous rather modest in size. Moreover, the most important deposits of terrestrial vertebrates and marine detritus, coastal karst cavities belong to the type of caves in which provide chronological records of great interest. the coastal mixing zone. Indeed, these are the type These deposits depend entirely on Quaternary appealing to travellers and naturalists, especially variations in sea level, due to glacio-eustatic factors. following explorations carried out for over a century The current Mediterranean sea level is also a factor in the tourist attraction Coves del Drac, namely determining the existence of underground lakes of «Dragon’s caves», in the Manacor municipality. In brackish groundwater, which fi ll lower reaches of the recent decades, a genetic model has been put forward caves.

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During the Pleistocene, glacio-eustatic sea level declines precipitated the collapse of cave walls and vaults, while later extreme phases of speleothem deposition contributed to masking the 2 characteristics of primeval cavities and collapsed matter. It should be noted that the magnitude of the rock fall and mechanical alteration of the rock mass largely determines the appearance of most galleries and cavities, while also being responsible 4 for the formation of exterior openings due to surface subsidence. In Mallorca these formations are known as abisaments in the Manacor region and esfondrats in Ses Salines. Meanwhile other galleries, usually found in less permeable rock dating to the Upper Miocene, are hardly affected by subsidence and here water corrosion morphology dominates, as in the case of external lagoon facies. 3 ■ THE PLAY BETWEEN COVES AND LITTORAL CAVES In Manacor harbour, the Genovesa cave is just over a hundred metres from the sea at the end of the Cala Anguila beach. The cove mouth measures 140 m in width, and it is 250 m in length (main polygonal axis of the cove) with an average width of 95 m. The cavity, a cave in the coastal mixing zone, runs 2,415 m and penetrates just over 500 inland, measuring © Grup Nord de Mallorca from the beach. Although a degree of protection is The Felanitx region (Mallorca) has a very rugged coastline, forming afforded by its classiﬁ cation as an EU landmark of many bays and headlands, like Cala Sa Nau, which opens onto a community interest and as a site of cultural interest 100-metre gorge and Cala Mitjana. Yellow indicates the location of by the Council of Mallorca, wastewater from the the underwater cave in Cala sa Nau (1), the Ses Barraques cave (2), villegiatura pours directly into the cavity. This is a Cala Mitjana cave (3) and En Bassol cave (4). good example of how coastal fragility is facing the onslaught further inland and could reach of coastal urbanisation, not only «THE ONSLAUGHT OF almost another 50 metres. on the surface but also below Further south is Falcó cove, COASTAL URBANISATION ground with the pollution of 300 m wide and 175 m long. groundwater and –via drainage– NOT ONLY AFFECTS THE It presents several karstic- of the sea. SURFACE BUT ALSO BELOW marine captures of considerable The cave known as Cova del GROUND WITH POLLUTION importance, such as the Es Pilar, also on Manacor coast, OF GROUNDWATER AND –VIA Coloms cave in Falcó cove and is a cave of great beauty with the Cala Falcó cave, along with its grand entrance and large DRAINAGE– OF THE SEA» other associated cavities. The columns or pillars, covered with Cala Falcó cave is believed to be blue seaweed stirred up by the related to the well-known Pirata- waves during bad weather, visible from ships sailing Pont-Piqueta underground system, measuring 3,091 along the coast. It is a good example of karstic-marine m in length, which less than 200 m away and runs capture with large speleothems that are eaten away 700 m inland. The subsidence of ancient galleries by erosion wrought by waves, and is a paradigmatic has separated this cave from the endokarstic system. example of the sea penetrating inland as the cavity Moreover, the encroachment of Es Coloms cave by recedes. At present, the sea inlet, besides the roof the sea has visibly shifted the line of cliffs inland, and of the cave, measures about 40 m, but the sea goes left layers of quaternary loamy sediments hanging on

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the sea cliff, which cling to the walls of the huge sea Marina de Pont cave. Of all these, the Cala Varques inlet. In addition to the beautiful lakes, this cave is B cave is the largest, running 1,068 m and with a notable for the presence of marine sands at the bottom maximum depth below sea level of more than 30 m. of a large dry gallery. Its location, at the back of the beach, is an indication 1 Just a short distance away and heading south, still of how the cave and Varques cove might eventually within the Manacor region, we ﬁ nd Cala Varques. The evolve in the event that the roof of the gallery, which mouth measures some 200 m is located at an altitude much in width, 320 in length and is below sea level, collapses. an average of 160 m wide. The In Felanitx harbour, the cave «COVA GRAN HAS RECEDED caves lining the cove shoreline known as Cova Gran, is a large and in direct or near contact MORE THAN 70 METRES FROM hollow cavity formed by marine Magnetic with the sea are: Cala Varques B THE COAST LINE, FORCING abrasion, which has retreated North cave, Cala Varques ACD or Es URBAN GROWTH PLANS TO BE over 70 m with respect to the Xuetes cave, Es Genet cave, Es CHANGED» coastline and whose entire roof

➞ Coloms cave in Cala Varques or is susceptible to collapsing and the Es Coloms II cave and the forming a recess measuring more than 120 m. This has forced the change of urban planning near the cave. Cala Sa Nau and Cala Mitjana are located between Portocolom and Cala Herrera, although closer to the latter, and about 5 km from the town of S’Horta. They are part of the Felanitx bay, lined by Neogene calcareous rock measuring up to 4 km wide. It is a very rugged area of coastline forming many bays and sharp headlands. Cala Sa Nau opens onto a 100-m gorge, measuring 500 m in length and with an average width of 55 m. An outstanding landmark in the area is the En Bassol cavern, located in the coastal mixing zone, lying in a NE-SW direction and measuring 1,491 m in length. It was found by chance during water prospection, and has no natural entrance. The abundance and beauty of the speleothems and the size of the galleries make it a major attraction. As the caves peter out and the sea encroaches inland, signiﬁ cant changes arise in the cove. In the Magnetic southeast, where there is a small sea inlet, the cliff North seems to have receded and the cove has eaten into En Bassol cave. Currently, marine sedimentation has ➞ closed direct communication between the cave and the sea on a human scale, although there is evidence that marine polychaetes and some crustaceans can still get into the cave. Other neighbouring caves are the underwater cave in Cala sa Nau and the Ses Barraques cave. The ﬁ rst is located in a geographical promontory and would pass right through the tip, from one side to the other, were it not for the sedimentation that accumulated during a Quaternary 200 m marine regression, blocking one of the entries with eolianite (consolidated dune). © Grup Nord de Mallorca Part of the En Bassol cave runs south, towards Cala The dolços (submarine springs) found in many coves and harbours in Mallorca are another example of the crosstalk between karst and Mitjana, which is just 170 m away. The cove mouth sea. The picture shows the Es Coll cave in Portocolom (Felanitx), a measures some 230 m and is 500 m in length, with an 7-kilometre-long formation found on a bend of the Es Rivetó. average width of 75 m. Just 180 m from the cove is the

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Cala Mitjana cave, running some 340 m, which was found during water prospection, when a 13-m-deep well was dug in the past. The surface water is used to irrigate a large grassy area, near the sea, which –among other things– currently characterises Cala Mitjana Creek. The situation of El Bassol cave suggests it is part of one system and landfall has rendered it impenetrable and isolated both cavities. In Cala Santanyí, located in the municipality bearing the same name, we ﬁ nd Es Riu cave, whose mouth is 260 m wide, length is 360 m and average width is 90 m. Es Riu is the sea upwelling of the Es Drac cave in Cala Santanyí, of which it forms part. It is located in the northwest, within a recess of the bay, measuring 27 m wide and 31 long and continues under the water until the accumulation of sand and stone closes off the connection with the rear cavity. It was formerly part of the Es Drac cave in Santanyí cove, an 803-m cavity running 228 m inland with respect to the sea. Due to subsidence and marine © M. A. Perelló. GNM sedimentary deposits, it was cut off from the rest, Cavities lining the coastal strip are a valuable natural heritage. while external subsidence –clearly noticeable in Many endemic troglobitic species live in the groundwater. In addition, geomorphological, palaeontological, chronological and aerial photographs– formed the sea inlet and played aesthetic wealth is very high. a role in the evolution of the creek itself. Moreover, noteworthy are the numerous underwater caves found at the mouth of the cove, where they form a complex

«SUBMARINE SPRINGS, CALLED DOLÇOS IN MALLORCA, TEND TO BE FOUND IN CAVITIES ACCESSIBLE TO PEOPLE USING UNDERWATER CAVING TECHNIQUES»

of tunnels with abundant entrances and associated forms of marine abrasion. Progressive landfall-driven disintegration of the Es Drac cave in Cala Santanyí, or other underwater caves, favours further sea inlet and encroachment of these spots, greatly affecting the evolution of the cove. Not only in the east of Mallorca are there genetic relationships among marine cavities and recesses. In Migdia, speciﬁ cally in the town of Las Salinas, on the Es Dolç beach (near Colonia de Sant Jordi) the Grup Nord de Mallorca team is studying an underwater cavity, discovered in 2011. This unprecedented cave has been created by processes of subsidence and sea erosion, and is known as the Es Dolç pond, as named by Cosme Aguiló. This gulf, penetrating over 40 m, has been formed by the retreat of the cavity and

is another example of karstic-marine capture in the © M. Luque

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coastal mixing zone, in this case composed of more recent matter (from the Pliocene) than in the eastern Mallorca (Miocene).

■ SUBMARINE SPRINGS IN COVES Submarine springs, called dolços in Mallorca, are not unique to coves but are commonly associated with them, and are often present in cavities accessible through underwater caving techniques. Cala Murta, in the Manacor region, has a mouth measuring 100 m in width, is 225 m in length and 45 m average width. The spring wells up on the north side near the bottom of the cove, just a few metres deep, coming from a cavity measuring approximately 100 linear metres. In periods of heavy rains followed by high seas, the upwelling water ﬂ ows in abundance. In addition to the freshwater drainage inﬁ ltration, the decline in sea level under high barometric pressure © A. Cirer. GNM

Above, groundwater speleothems (carbonate deposits of precipitation) from the ceiling of the cave Es Drac at Cala Santanyí indicate ancient Mediterranean sea levels. «THE ALGERIAN EARTHQUAKE, IN 2003, LEFT ES RIVETÓ DRY, CAUSING STRONG Below, the sea cave Es Pont in Cala Varques (Manacor) is a good example of karstic-marine capture where there is a clear WATER CURRENTS TO ARISE FROM DOLÇ interaction between karst processes and coastal dynamics. AND DRAGGING FISHING BOATS UP THE SLIPWAY»

conditions is a major factor underlying the water fl ow, which is quite spectacular and gives rise to turbulence that is visible even from the headlands. By contrast, the deposition of marine sediments, especially sand, due to storms and ocean currents, can block the underground conduit. However, when weather conditions change, the water gushes out with such force that it fl ushes the sand out leaving the gallery empty again. This water source is undoubtedly related to the Es Drac caves, which are just a few metres away. Further south is the Es Coloms cave in Cala Varques, which is genetically related to Genet’s cave and separated by a landfall. Then in Portocolom in the Felanitx Marina, we fi nd Es Rivetó, name given to a bend in the harbour that resembles an inland creek. This name is usually associated with underwater springs, like S’Esdolç or Aigo Dolça, located within Es Rivetó. The spring, which issues from dry dock, is the underwater entrance to the cave of Es Coll, an important endocarstic formation measuring 7,090 m in length with strong structural organisation, where permeability associated with the fracture is important

Cova del Pilar, in Marina de Manacor. The progressive collapse of the cavity is giving rise to inland sea encroachment, which is currently about 40 m, although the sea could come inland by almost 50 m more. in that these materials are signifi cantly less porous Cala Sa Nau is 2.5 km to the south, where we have than reef deposits found in other parts of Migdia. another rivetó place name. The water fl ows under the The barometric changes translate into current output sand of the sea bed on the south side of the beach, or input, by way of ducts, to compensate for the just over a metre deep. This dolç –freshwater spring– difference in sea level and groundwater. Thus, when comes from the Ses Barraques cave, very close to the the sea rises due to this direct En Bassol cave, and characterises connection with the cave, the the beach given the signifi cant water enters. The opposite thermal contrast it creates. In «ES COLOMS CAVE IS NOTED phenomenon occurs when the summer, the water leaving the sea level drops, as the water FOR ITS BEAUTIFUL LAKES endokarstic system can make runs out of the cavity searching AND THE PRESENCE OF a difference in temperature for hydrostatic equilibrium. An MARINE SANDS LINING THE between the sea and groundwater extraordinary event happened LARGE DRY GALLERY» of 6 to 10 °C. Also Es Riu cave in the aftermath of the Algerian in Cala Santanyí was inspired by earthquake on June 4, 2003 this place name, corresponding at 18.33, when the sea water to the freshwater spring from the

withdrew totally, leaving Es Rivetó dry. This Es Drac cave in Cala Santanyí. © M. A. Perelló. GNM phenomenon resulted in incredibly strong currents Dolç is situated in a completely different coastal that arose from Dolç and even dragged the ﬁ shing landscape, without cliffs, like the beaches of Colònia boats that were moored near the slipway. de Sant Jordi (Ses Salines). The beach goes by the

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same name, due to the lower salinity of the sea and the shocking temperature contrast between sea water and the groundwater that emerges in the Es Dolç pond. There are many factors and processes involved in the formation and evolution of coves. The presence of karst cavities captured by marine erosion and then progressively dismantled is an additional factor to consider. In some small coves or inlets making small indentations in the coastline this may have been a determining and almost exclusive factor. Meanwhile, its contribution to the evolution of larger coves and even natural harbours may have been more or less important. Many freshwater upwellings –known as dolços– come from karst cavities, from which continental waters drain and interact hydrologically with the sea, representing an inland encroachment of the sea.

«THERE ARE MANY FACTORS Blocks accumulated due to the progressive caving in of Genovesa cave, a formation reaching just over a hundred metres from the AND PROCESSES INVOLVED sea in Cala Anguila Manacor. IN THE FORMATION AND EVOLUTION OF COVES»

ACKNOWEDGEMENTS Thanks to Toni Cirer and Miquel Àngel Perelló, from Grup Nord de Mallorca, for the underwater photographs and Miquel Àngel Perelló, GNM, and Manolo Luque, GELL, for the aerial photographs. These studies have been carried out over recent years, thanks largely to Obra Social de Sa Nostra funding within Biodiversity Conservation Projects.

BIBLIOGRAPHY AGUILÓ, C., 1991. La toponímia de la costa de Felanitx. Centre cultural de Felanitx. Felanitx. GINÉS, J., 2000. El karst litoral en el levante de Mallorca: una aproximación al conocimiento de su morfogénesis y cronología. Doctoral Tesis. Earth Science Departament. University of the Balearic Islands. Unpublished. GRÀCIA, F. et al., 1997. «Les coves de la zona de ses Partions-Portocolom (Felanitx, Mallorca)». Endins, 21: 5-36. GRÀCIA, F. et al., 2011. «Cavitats subaquàtiques de la franja litoral de Mallorca». Endins, 35: 103-132. ROSSELLÓ, V. M., 2005. «Cala, una mesoforma litoral: concepte, models i aproximació morfomètrica». Cuadernos de Geografía, 77: 1-18. ROSSELLÓ, V. M. et al., 2002. «El papel del karst en el macromodelado litoral: el ejemplo de las cales de las Islas Baleares». In CARRASCO, F. et al. (eds.). Karst and Environment. Patronato de la Cueva de Nerja. Málaga.

Francesc Gràcia. Grup Nord de Mallorca Speleology, karst and coastal geomorphology research group, University of the Balearic Islands (Spain). Bernat Clamor. Grup Nord de Mallorca Speleology (Spain). Pere Gamundí. Grup Nord de Mallorca Speleology (Spain). Hidden wealth present in the cavities calls for conservation. The Joan J. Fornós. Karst and coastal geomorphology research group picture shows En Bassol cave (Cala Sa Nau), a cavity without a University of the Balearic Islands (Spain). natural entrance, found by chance during water prospection. Damià Vicens. Balears Natural History Society (Spain).

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