We can assign a date to the beginning of the Grotte di Castellana about 90 million years ago, during that period of geological time called the Cretaceous, Puglia was submerged by an ancient sea, in which lived vast colonies of shellfish and marine plants. For millions of years these forms of primordial life have left their shells and their carcasses on the seafloor and shaped a gigantic deposit of mud and sand.
And so, from 65 million years ago, this thick layer of limestone begins to emerge and give a shape to Puglia as we know today.
In the basement, the filtered water produced by heavy rainfall had undertaken an underground river that due to mechanical and chemical erosion dissolved limestone layers creating corridors and larger and larger spaces.
Over time, the phenomena of orogeny lifted the limestone layers which today form a part of the Murgia in the southeast of Bari and the water, that had completely flooded the underground cavities, led deeper into the underground freeing up large spaces and large corridors.
Some layers of limestone, due to fractures and the lack of water pressure, collapsed creating a big breach at the top from where peeped a little bit of the sky and a warm beam of light: it was La Grave.
Then in the Quaternary (2.5 million years ago) began the stage called “beautification of the caves”. The trickle caused by the slow infiltration of stormwater laden with calcium carbonate once reached the empty cave began to fall and deposit tiny crystals both on the vault and on the ground, caused the growth of stalactites, the formations that hang from the ceiling, and the underlying stalagmites.
With the passage of time, almost two million years, the progressive growth of stalactites and stalagmites have filled almost entirely with the cavity and formed with their union many gigantic columns you can enjoy along with all the other amazing concretions during the extraordinary itineraries.
An attraction for visitors and scientists is still the eccentric stalactitesc which are concretions that defy the law of gravity growing horizontally or spiral and the “Pannocchie” (cobs).