Grotte e abissi in terreno Argilla

Clay is a very fine-grained, plastic sediment that acts as an impermeable layer; the few associated cavities are usually conduits in soft materials or fillings of other caves. The catalogue lists 3 cavities in clay: 2 caves and 1 pit, with a total passage of 69 m and a maximum depth of 5 m.

The longest cavity is the Forat de Can Cademont del Bosc, at 30 m, which is also the deepest, at 5 m; it is a collapse with 5.5 metres of vertical drop in clay at Maià de Montcal, opened in October 1998. It is followed by the Cova dels Mongons, at 20 m, a small semi-artificial cave of historical interest in Tarragona formed by two cavities joined by an artificial gallery, and the Cova del Peiró, at 19 m, a small cave in Mont-roig del Camp opened in foothill materials and scree cones, with a 10 m wide entrance subdivided into 4 entrances.