The natural shelter of La Coma is on the left bank of the Marfà or Golarda stream, not far from the farmhouse of La Coma and a few hundred meters before the confluence of the stream of La Baga Cerdana or L’Om, in the municipality of Monistrol de Calders. The shelter of La Coma is definitely big either in length, height and depth.
The inside of the shelter of La Coma is dry. In normal circumstances the water goes only by the stream a few meters further and lower. But from time to time the great floods multiply the flow raising to the level of the shelter; then the tremendous erosive force of the unleashed water digs and deepens the shelter.
On 10.10.1994, the entire basin of the river Calders, including the stream of Marfà at its headwaters, suffered an exceptional flash flood with a return period of, who knows, maybe millennia. The flash flood caused widespread damage and washed away the bridge in Colonia Jorba. 30 years later, there are still large poplar trunks in the shelter of La Coma whose dryness prevents from wood degradation as a silent proof of the strength and level that the Marfà stream reached in 10.10.1994 (2nd photo).
The greater resistance of the thick layer of conglomerate than that of the sandstone below together with the erosive action of the stream explain the origin of the natural shelter of La Coma.
In the 3rd image, the ICHN-Bages group in the La Coma shelter during the naturalist outing to the valley of Marfà on 25.10.2024.
[photos Jordi Badia]
- Further information in Notícies de la ICHN nr.174.