"If you would like to hear and understand the stories that stones tell…. At midnight, under the light of the moon, pick an arnica leaf … squeeze it between your thumb and little finger and smear the juice on your left ear …"
(L. Pesek, A Stone's Voyage)

To fully understand the importance of geological history, or the influence that it can have on the identity and development of an entire region, it is necessary to pay attention not only to the marvelous landscapes that make up our natural heritage, but one must also take a look at the factories and other projects that man has been able to create over the centuries by intelligently exploiting the geological resources that surround him. So, before travelling in time through the Quaternary or Jurassic Periods, let's stop a moment and take another look at the castles of the Puglia, its magnificent churches and cathedrals , the fortified plantations of the Murgia, its enchanted "trulli", and the symbolic burial structures of the Dolmen and the Menhir's. We immediately realize that there is only one fundamental element which unites them all and has allowed them to survive through time: limestone. Almost 80% of the Puglia is made up of limestone and dolomite, and the incredible varieties of its forms. If we wish to understand how this type of rock is formed, this "cornerstone" that has given life to extraordinary landscapes and man-made structures, and which constitutes the symbol and very essence of our region, we need only fly to the Caribbean, over ten thousand kilometers away, to the collection of islands known as the Bahamas. We have come here not for the resorts, but to discover the coral reefs, the archipelagos, the lagoons, the geological layers and the barrier reefs that are silhouetted in the warm, shallow seas of these latitudes. But let us proceed by steps…

Phase One
In the Middle and Lower Jurassic, about 190 million years ago, Italy did not exist, certainly not the Puglia, at least not as we see it today. But, following the breakup of PANGEA (the mega-continent that included most all of the dry land) several small gulfs and interstitial seas, with a whole series of islands and rocky shores, began to form, very similar to what we see today in the Bahamas. Our limestone began to form in that context, in that far-off time, thanks to a collection of small living organisms that removed calcium carbonate (CaCO3) from the water to make their shells. These organisms were, for the most part, bivalves and invertebrates, and when they died, their shells were deposited on the seabed and started accumulating, one on top of the other, until they formed, in this manner, the first strata of sedimentary calcium carbonate, in the form of sand and mud. These little animals, like coral, can only live in the tropical and equatorial latitudes, with a warm and humid climate and a shallow and transparent sea. This means that, in the Jurassic, the Puglia, or rather the complex of calcium carbonate layers that represented it, found itself closer to the equator than it is now, actually in the tropics. It is only after the shifting of the continental plates, which occurred 65 million years ago, that our Puglia began to "sail" towards the north, slowly being carried into the position in which we find it today. The calcium carbonate layers, and the environmental system that created them, continued on almost completely undisturbed for an unimaginable length of time, 125 million years! To make a temporal comparison, it is enough to remember that the entire history of human civilization has occurred in the last 10 to 12 thousand years. The incredible growth of these structures is evidenced by the fact that in Puglia, right under our feet, are almost 2,000 meters of limestone and dolomite sediment. This is explains how, as the animated film clip shows, the vertical and lateral growth of the layers went on contemporaneously with their deepening ("subsidence"). Thus, while the older strata were being pushed towards the bottom, sedimentation continued undisturbed with the laying down of new shells and carbonaceous mud that piled one atop the other, forming in this manner, the colossal sedimentary structures that we are able to observe today in any one of the many open caves in our territory.

The Dinosaurs
The tropical islands, lagoons and geologic layers of the Jurassic and Cretaceous Periods were widely visited. We have the proof, from 1997 when, in a limestone cave in Altamura, some enthusiastic visitors discovered and recognized hundreds of "strange" fossilized tracks in the rocks. By now we know for sure that these are the tracks of dinosaurs, those terrible lizards (sauro=lizard, deinòs=terrible) that inhabited our planet during the Triassic, Jurassic and Cretaceous Periods, for over 150 million years (and which Homo sapiens has dominated for only 2 million years!). The dinosaurs that inhabited the calcium carbonate layers of the Puglia were partly herbivores, thanks to the rich tropical vegetation which covered those islands, and partly carnivores. Perhaps it was actually a Brontosaurus, about 25 meters long, sinuous and powerful, who, together with other members of his group, left those tracks along the water's edge, right there, on that tropical beach, south of Bari, on a spring morning 70 million years ago…. Those imprints on the beach were miraculously preserved thanks to the rapid drying of the calcium carbonate mud in the sub-tropical climate, and to a series of microscopic algae that trapped the footprints, allowing for their conservation until this very day. But those footprints would never have reached us if that calcium carbonate mud had not, over time, turned into stone….

Phase two.
Time, pressure and temperature. These are the three fundamental variables which intervene in all geological processes and phenomena. These are the three variables which led to the solidification ("diagenesis") of the sand and calcium carbonate mud, transforming these loose sediments into the limestone rock that we see today in the buildings and surfaces of works of art throughout our region. Temperature and pressure, in particular, influenced chemical reactions, provoking unstable minerals to dissolve and the successive precipitation of the cement that must bind the microscopic grains together. Pressure, in its turn, acted during the burying phase, compressing and compacting the various strata, while time, in the end, assured the imperturbable, incredible transformations that a rock habitually endures during its long life. Thus, at the end of the Cretaceous Period, around 65 million years ago, those tropical islands were already good and formed and were completely out of the water and with the greater part of their sediments transformed to limestone and dolomite. Sixty-five million years ago … it's a fundamental date, a frightening date! A gigantic meteorite, probably from the asteroid belt between Jupiter and Mars, or perhaps farther away, collided with our planet, falling on the area occupied today by the Yucatan Peninsula in southern Mexico. The impact was terrifying. Most of the species then alive were literally swept off the face of the planet in a few decades! And along with them, the majestic dinosaurs, probably the greatest animal species that our planet will ever know. Still 65 million years ago, something else happened almost as frightening. The continental plates into which our planet is divided began to shift irresistibly as if they wanted to find a better position. Among these, the enormous African plate began to rotate in a counter-clockwise direction and to move northwards, in the direction of Europe and the many calcium carbonate layers that by now made up Italy. Thus, beginning in the Oligocene and continuing to the Upper Pliocene Period (50 to 55 million years ago) the African plate, and its more northerly portion, the so-called African promontory, came in contact with the European plate and the Adriatic micro-plates, among which was the Puglia, causing first the Alps and then the Apennines to rise up. The Puglia was not directly involved, as was the rest of Italy, but it did experience strong "stress" that caused it to fracture in many places and to take on the shape of giant steps. The forces of compression from the African Promontory, in fact, caused the massive limestone layers of the Puglia to bend and break. They then began to push like giant steps under the Apennines in the direction of the Basilicata. These great fractures involved our region, which sank with the same step structure, between the Gargano and the Murge, creating the prerequisites for the laying down of the sediments of the Tavoliere delle Puglie (the Puglia Plateau), and going on to form, between the Murge e the Serre (Sierras) of Salento, the sediments of the Brindisi-Lecce plain. More recent geological history, that of the last 2 to 3 million years, has been dominated by a more diffuse regional uplifting, more pronounced in the Gargano area (which is still rising) compared to other areas. During this period, the region was also subject to variations in the level of the oceans caused by the glaciation of the Quaternary Period, which brought about intense shaping of the coastline, which is still going on. Today's geological history is now everyday history. It is the story of the limestone erosion that has produced the magnificent Grottos of Castellana , of Zinzulusa or of Santa Croce (Bisceglie). It is the story of the Pulo di Molfetta, of the Caves of Altamura, of the Gravine of Laterza, of the Gargano Promontory and a score of marvelous places and landscapes. But it is also the story of the hydro-geological disasters that have troubled a good part of our region, from Sub-Apennine Dauno, to the anthropological caves of Canosa di Puglia, from the flooded areas of the Salento to the fragile cities that are located on the coastline or on the Tavoliere delle Puglie. And it is a story that must be respected, loved and preserved, not only for ourselves, but above all for the generations which one day will have the good fortune to inhabit this splendid land.