GSA Today's “Geology Through the Lens” - Matera’s Timeless Geological Legacy

In the February 2025 issue of the Geological Society of America’s publication "GSA Today", I had the distinct honor and privilege of showcasing my photo of the ancient and modern city of Matera with an accompanying description. 

Taken during a recent visit to the Southern Italian regions of Basilicata and Apulia, Matera and environs is heaven on earth for geologists, anthropologists, paleontologists, botanists, historians, tourists, hikers, bikers, gastronomes, oenophiles, sociologists and cinephiles.  The text that accompanies the photo is a bit verbose (my forte) and condensed, but the editors only allow so many characters.

In the coming months, I plan to post a detailed account of the geologic evolution of the karstic carbonate platform on which Matera.  In the meantime, I offer the following view of the ancient and modern city taken from the bottom of Gravina di Matera (Gorge of Matera) and a few images from the Alta Murgia plateau (Apulian Platform) plateau on which the city resides. 

South-facing View of Gravina di Matera

Located on a karstic plateau of the Tertiary-uplifted Apulian Carbonate Platform of Mesozoic African affinity in the Basilicata region of southern Italy (“instep of the boot”), Gravina di Matera is riddled with thousands of solution caves that, in part, constitute the city of Matera’s Sassi (the “stones”) that is perched on the edge of the gorge.  Many caves have Neolithic documentation, and those of Matera have been continually inhabited since the Paleolithic with quarried Renaissance facades over their entrances.  Following a period of extreme overcrowding, disease, poverty and national shame in the twentieth century, Matera emerged as a 1993 UNESCO World Heritage Site and first-class tourist destination.

North-facing View of Matera from the Bottom of Gravina di Matera 

Matera's occupation spans a significant portion of human history, with evidence of settlement dating back to the Palaeolithic period, approximately 9,000 BC, possibly older than 10,000 BC. That makes it one of the oldest continuously inhabited settlements in the world - due in large part to the region's karstic geology!

A visit to Matera must include a moderately challenging, two or three hour hike into the gorge to the opposite rim and back.  There are trail maps available online, but the layout isn't complicated, although signage could be better. You will find that there are numerous confusing subtrails that branch off, but they eventually converge back into a main trail. Fortunately, you never lose the sense of where you are or where you're headed, so you can't get lost.

Near the top of the opposing wall you will be rewarded with a number of caves with rupestrian (located on rock walls) frescoes, painted by Greek monks seeking religious freedom and isolation in the 8th to 13th centuries. Familiarity with the gorge's calcareous stratigraphy and tectonic provenance before you head out is highly recommended. 

Lastly, don't forget to pack water, some of the locally famous Matera sourdough bread, a little local cheese and a few Leccino black olives. Molto delizioso! 

Pontrelli Quarry and Dinosaur Track Site

Located about 10 miles north of Matera and a few miles east of Altamura on the Alta Murgia, the floor of the long-abandoned Pontrelli Quarry, from a distance, looks like machined striations created by stone workers. To the surprise of paleontologists, it turned out to be an enormous Late Cretaceous dinosaur tracksite with over 4,000 footprints created by over 200 mid-sized, quadruped dinosaurs belonging to at least five different species. 

The ichnofossils (preserved traces of animal activity and behavior) were created within the shallow-water, peritidal Altamura Limestone formation (Calcare di Altamura in Italian).  It was uplifted intermittently throughout the Cenozoic by orogenic events that ultimately formed the foreland of southernmost mainland Italy and the Adriatic Sea.

The discovery is unique in several respects. Fossil dinosaur tracks from Italy are rare, and the location in the Apulian foreland sheds light as to the climate at the time of deposition, which was similar to the Bahamas. In addition, it reveals new and critical information regarding the tectonic evolution of the western Paleo-Tethys Ocean (the proto-Eastern Mediterranean). 

As a result, it is believed that the Apulia and Basilicata regions originated as part of the Adria microplate of North African plate affinity (originating perhaps as an African promontory at the time), before rifting, drifting and colliding with proto-Southern Italy.

Pulo di Altamura Sinkhole

Located about six miles NNW of the quarry and five miles north of the town of Altamura, Pulo di Altamura (an early Italian and perhaps regional term for a sinkhole with potential Indo-European origins) is the largest sinkhole (doline in European geological terms) on the highly permeable plateau of Alta Murgia. The topographic depression formed by karst solutional processes, as did Gravina di Matera in association with fluvial dissection, that progressed in a subterranean locale to the extent that collapse of overburden occurred. 

Some researchers believe that parts of the eastern Grand Canyon of Arizona may have evolved in this manner in regions of limestone stratigraphy that, over time, facilitated development of a west-flowing, ancestral Colorado River through the Kaibab Upwarp via the collapse and coalescence of sinkholes. It might have allowed subterranean flow with eventual connection between the eastern and western Grand Canyon. Such a process may have occurred on the Apulian plateau and resulted in the formation of a gorge (European for canyon). 

Karst solutional processes occur when neutral pH rainfall becomes acidic by absorbing atmospheric carbon dioxide (and other gases) and when groundwater acquires additional acidity from decomposition of organic matter in the soil and root respiration. Mildly acidic, the groundwater chemically dissolves and mechanically erodes the calcium carbonate mineralogical component of the uplifted calcareous seafloor platform that collapses when undermined. 

Notice that the walls of the sinkhole are peppered with caves, as are those of Gravina di Matera. They show signs of human habitation dating back to the Upper Paleolithic, at least 5,000 years ago through the Iron Age and into the Middle Ages. Archaeological finds include human remains, engraved pebbles and a fossilized shell, indicating the site was used for cults and resource exploitation.

I didn't encounter anyone on the wonderful 5.1 mile loop-hike to the sinkhole across the unspoiled plateau and wheat fields of the Alta Murgia National Park. 

The Altamura Man

As at ancient Matera, many of the karstic caves that developed on rocky ledges of the Alta Murgia were inhabited by an archaic form of Homo neanderthalensis that lived in the region during the Middle-Upper Pleistocene between 170,000 and 130,000 BP.  In fact, a deep karst cave complex near the sinkhole called Lamalunga, discovered in 1993 by cave explorers but closed to the general public, contains a complete Paleolithic skeleton, the most intact and oldest ever discovered in Europe that has been accurately dated and awaits DNA sequencing.

 

Dubbed Altamura Man and irretrievably inverted and encased in calcareous rock and covered with corroloids (cave 'popcorn'), caused by aerosol spray of precipitated calcium carbonate, the skeleton is in an excellent state of preservation, having been completely replaced by calcite (the most stable polymorph of calcium carbonate).  How does that happen geochemically? 

Within the cave and driven by several factors, calcium carbonate precipitates out of saturated solution in the reverse direction of the aforementioned karst chemical reaction, as carbon dioxide degasses back into the cave's atmosphere and as water slowly drips from the void's walls and ceiling.  Over time, calcium carbonate is redeposited forming speleothems - cave formations such as stalactites, stalagmites, flowstones and the Altamura Man's entombing calcareous armor. 

The Alta Murgia plateau is peppered with such caves ('grotto' in Italian), some open to the public with tours, and many await discovery and exploration. One wonders what finds will be disclosed in the future, hominins or otherwise. (Image from Wikipedia)

My Lovely (Very Hungry) Daughter

By the way, if you pay a visit to the Apulia and Basilicata region, the local cavatelli pasta ('little hollows' and for me, reminiscent of Matera's karstic solutional caves) is delicious but challenging to roll by hand, as my daughter and the rest of our family discovered in a cooking class at "Cook'n Fun at Mary's" (shameless plug) in Matera. A few glasses of the local wine didn't make things any easier. My forlorn culinary creation is on the top tray.