Altamira Cave is located in a karst system witch, in geological terms, is coming to the end of its life. This natural process of degradation is aggravated by the structure of the cave, formed by horizontally bedded limestone strata, increasing the danger of breakdown and the collapse of large blocks.
Because of this risk of a large-scale collpase, between 1924 and 1950, thick walls were built inside the cave in order to support the roof and avoid the total loss of the cave. This was the best solution that the technology of the time could provide, although it left the Chamber of the Paintings totally isolated from the rest of the cave. From that moment, the natural conditions which had preserved the paintings during millennia began to change.
