Grotte e abissi nella grande unità geologica Serralada Prelitoral

The Serralada Prelitoral is an inland mountain alignment of the Catalan Mediterranean system, parallel to the coast and separated from the Litoral by the Prelitoral depression. Its limestone and conglomerate massifs —Montserrat, Montsant, Prades, Sant Llorenç del Munt— hold a large share of the country's major cavities. The whole comprises 1851 cavities, of which 1148 are caves and 703 pits, with a total length of 93408 metres and a maximum depth of 283 metres. It includes 26 child units.

Among the longest cavities are the Cova Urbana de Tarragona, with 2441 metres, discovered by chance in 1996 during the construction of a car park at carrer del Gasòmetre, no. 32; the Forat de Riu Algars, with 2000 metres of passage at Alfara de Carles (el Port), with a height difference of 43.50 metres and a meandering route, of which the surveyed length is 1190 metres; and the Avencs I Coves de la Febró, a group of fissures with 1810 metres of passage at la Febró. Also notable is the Avenc de la Crisi, 148 metres deep, with the largest vertical drop in Catalonia, el Port (Tortosa), and the Avencots dels Motllats de la Pona, with 1178 metres of passage at the Motllats de la Pona, La Febró, with 6 entrances, of which only number 1 (Avenc del "Neng") and number 2 are accessible.

As for depth, the Avenc Cp.6 reaches 283 metres on the S slope of Mont Caro (el Port), at the head of the barranc de Cova Pintada, explored by the Espeleo Club Tortosa since 1985. It is followed by the Avenc Cp.1, with 195 metres of height difference in the Cova Pintada sector (el Port), with an entrance leading to subhorizontal conduits, chambers and shafts down to the -179.5 level; the Avenc del Camí de Xàquera, 180 metres deep at Tivenys (Baix Ebre), discovered and cleared by the GIE – CE Gràcia around 1972 or 1973, and where in 2014 the UEC de Tortosa reached -180 m; and the Avenc dels Mamelons, 167 metres deep at the Mola de Catí (el Port, Tortosa), with an estimated total length of 700 metres and several internal routes.