Caves and potholes in the Les Guilleries geological unit

The Guilleries are a massif of sandstones and granites between Osona and the Selva, with cavities linked to detrital and crystalline rock. The catalogue lists 24 cavities: 23 caves and 1 pit, with a total passage of 1240 m and a maximum depth of 11 m. The lithologies present are sandstones (17), limestones (4), marbles (2) and conglomerates (1).

The longest cavity is the Cova de les Grioteres, at 323 m, in Vilanova de Sau (Osona), with a reticulate layout, seven entrances, labyrinthine galleries and archaeological remains from the Neolithic to the Middle Ages. It is followed by the Cova del Pasteral, at 290 m, in la Cellera de Ter, with two entrances, galleries and a lower fissure, damaged by mining extraction, and the Baumes de la Molera d'ausió, at 270 m, in Sant Julià de Vilatorta (Osona), with underground sections and remains of a millstone documented in 1362.

The Cova del Nou Nou, at 95 m, in Vilalleons (Sant Julià de Vilatorta), located in 1988 and surveyed by the GES-CM Terrassa on 28-5-1989, reaches a height difference of -11.5 m. Other cavities are the Cova del Mas Salou, at 38 m, documented by the GE Badalona in April 2022; the Avenc dels Gossos, 6 m deep in Tavèrnoles, explored in 1976 by the GE Mollet; and the Balma de la Baronessa, with 23 m of passage in Tavèrnoles, with a spring, retaining walls and a 6 m water mine.