The bridge of Les Arnaules or Pont Foradat (= holed out bridge) is a natural rock bridge. It’s located in the right slope of the valley Llobregat, above the village of Pont de Vilomara although township Manresa, in the area that is known as Les Arnaule. It is a long strip of nummulitic limestone rock that connects both riversides of a small, sporadic stream in the main slope. Nummulitic limestone is a hard rock. The close inspection of its recent flakes displays that it is made of small fossils as lentils, the nummulites, which are glued by limestone concrete. The layer of nummulitic limestone outlines in the slope profile because the materials above and below were eroded. The layer of limestone should have had two parallel cracks where now there is the bridge. The erosion by the small tough with a high slope stream has dig out the ground from the internal crack isolating the slender bridge rock. The bridge of Les Arnaules is 27 m total length, with 13,2 m suspended in both sides; it’s really narrow, between 2,7 m maximum and only 0,85 m minimum width and 10,7 m high to the stream.
The highway C-16 Terrassa-Sant Fruitós is placed few meters above. The natural bridge may have been buried by the highway, but fortunately it was left out of the works.
[photo Jordi Badia]