La Trona is a large rocky outcrop that juts out from the sunny straight walls of the Cingles de Bertí, dominating the Sot del Bac valley, despite belonging to Sant Martí de Centelles. This fact has caused that in its obaga part there is a small area with a very specific microclimate. In addition, it is a good example of an off-road climbing school. The rock isn't exactly Yosemite granite or Verdon limestone, but it's pretty good quality compared to the vast majority of Osona's walls.
It dominates the hidden natural link between the Vallès and Osona, looking towards the Vallès despite belonging to Osona, in the middle of the cliff that follows the gorge formed by the river of the same name.
The name probably comes from its curious shape, since it could well be the high chair of some giant. From its summit you can see the southern part of the Congost valley, closed by the Puiggraciós and the town of La Garriga; to the east you can enjoy the entire western sector of the Monseny massif, dominated by the Turó del Tagamanent with the Pla de la Calma and the Carenes d'en Bosc in the background; and towards the north, if the elements cooperate, you can see the Pyrenees. To the west is the entire eastern sector of the Cingles de Bertí up to its buttress of Puiggraciós.