Balearic Islands Regional Geology and Environment: Lithology, Structure, Coasts, Karst and Island Hazards
This domain applies the general syllabus to the Balearics. The exam expects you to place the islands in the Alpine framework, describe the main lithologies and structures, and connect them to coastal, karstic and hazard processes.
Structural setting
The Balearics lie in the western Mediterranean on the Balearic promontory, part of the External Betic zones linked to the Iberian Peninsula and the Betics. The islands are the emerged summits of horst-and-graben blocks shaped by Miocene Alpine compression followed by extensional collapse.
Main units
- Mallorca: the Serra de Tramuntana in the northwest is a thrust belt of Mesozoic carbonates, marls and Triassic evaporites; the Serres de Llevant in the southeast repeat the pattern; between them lies the central Pla and Raiguer basins filled with Miocene and Quaternary deposits.
- Menorca: two contrasting halves. The north has Palaeozoic (Devonian-Carboniferous) and Triassic rocks with thrust structures; the Migjorn in the south is Miocene platform carbonate.
- Ibiza and Formentera: mainly Mesozoic and Cenozoic sequences dominated by thick Miocene marls and limestones, with Quaternary dunes.
Evaporites and karst
Triassic and Messinian evaporites (gypsum, salt) occur in the Neogene basins; salt pans exploit the coastal flats. Karst is extensive in the Mesozoic and Miocene limestones: dolines, sinkholes, poljes and caves such as the Coves del Drach, dels Hams and d'Artà in eastern Mallorca, and the coastal karst around Ciutadella in Menorca. Coastal karst mixes fresh and marine water, producing characteristic flooded galleries.
Lithology and building
Miocene calcarenite, known locally as marès, has been quarried at Santanyí, Felanitx and Muro and used for the cathedral of Palma. Limestone, gypsum and salt are the main economic minerals.
Coasts and hazards
The coast alternates rocky headlands and pocket calas, with Posidonia meadows offshore and dune systems such as Es Comú de Muro. Main hazards: flash floods (Sant Llorenç, 2018), summer forest fires, drought and overexploited aquifers with seawater intrusion, coastal erosion and tourism pressure.
Worked example
Why does northern Menorca have a rugged rocky coast and the south a lower, cliff-fringed carbonate coast? The north exposes resistant Palaeozoic and Triassic rocks in thrust sheets, producing headlands and small coves. The south is Miocene calcarenite and marl, softer and more uniform, producing long low cliffs and gently sloping platforms. Answer by linking lithology and structure to coastal landform.
Traps that cost marks
- Calling the islands volcanic; they are sedimentary and orogenic.
- Treating Menorca as geologically uniform rather than two contrasting halves.
- Placing the Tramuntana as a simple horst, ignoring its Miocene thrusting.
- Forgetting that seawater intrusion and flash floods are the signature island hazards.