Grotte di Castellterçol

Castellterçol, a municipality in the Moianès, has 7 catalogued caves, all of them rock shelters. Together they total 54 metres of length and reach a maximum depth of 2 metres. The dominant lithology is sandstone, present in 5 of the cavities, followed by conglomerate and travertine, with 1 case each.

Among the cavities, notable ones include the Balma del Pedrós, 13 metres deep and more than 50 metres wide, opened in sandstone with the upper visor formed by conglomerate; the Balma del Solell d'esplugues, with a low ceiling, beside the riera de Fontscalents, 100 metres wide and 10.5 metres maximum depth; and the Bauma de la Riera de Sant Joan, 49 metres long, 9 metres deep and 6 metres high, catalogued in October 2018 by the GE Badalona.

Other cavities are the Balma del Rentador de la Llana del Roquer, a large worked shelter of former industrial use with a wool washing place that operated between the 16th and 19th centuries, and the Balma de la Font de la Vinyota, which brings together two shelters and a spring at the riera de Fontscalents. The Balma de la Vinyota, also at the riera de Fontscalents, is 37 metres long, 5 metres deep and 4 metres maximum height, crossed by the water of the riera.