Imagine this: you’ve traveled not only through the three dimensions of space to Italy, but through the fourth—time—and are now millions of years in the past, looking on as the Adriatic and European tectonic plates collide, distorting the Earth’s crust to send the mountain belts we now know as the Apennines skyward. Central Italy’s geology is unparalleled; not only are its undulating rows of mountains and valleys stunning to observe today, they record a history that was ancient long before the Roman Empire crystallized. During a recent university field geology trip to the Marche region, the director of the Osservatorio Geologico di Coldigioco—our home base—taught us to see the world in five dimensions: space (x 3), time, and imagination.
A view of the Apennines from the Apennines, facing east towards the Adriatic.
With a geological lens, you too can find even more in Italy than the usual history-art-wine-food-fashion-amore package. Rocks, you may be thinking. I have no interest in rocks. What about dinosaurs? What if I told you that in Italy you can literally reach back in time to touch the moment of the dinosaurs’ extinction? You can roam natural caves bigger than cathedrals. You can sip sediment-crafted wine as you sit on an outcrop that proves that the Mediterranean once dried up, even as you admire that very sea patiently rounding pebbles just meters away. All you need to do is incorporate an extra dimension into your travel plans: imagination.
The K-T Boundary
Space: Bottaccione Gorge, Gubbio, Province of Perugia, Umbria
Time: ~66 million years ago (mya)
Imagination: You’re reaching out to touch an unremarkable-looking layer of rock when its history flashes through your mind. An asteroid strikes present-day Mexico’s Yucatan peninsula, creating the Chicxulub crater. A massive dust cloud explodes into the atmosphere and enshrouds the Earth, obstructing the sun and leading to the extinction of countless creatures, including the dinosaurs and many miniscule sea dwellers known as foraminifera. The latter sink to the seafloor and become fossilized over time. The dust gradually settles, forming a thin layer across the planet. This layer includes iridium, an element rare on Earth but relatively common in extraterrestrial matter. 66 million years later, in the 1970s, a geologist notices that most of the foraminifera present as fossils in the lower strata—or layers—of the outcrop before you do not show up in the higher strata. This suggests the earlier organisms went extinct before the higher, more recent strata were deposited. He discovers an iridium spike in the layer that separates these fossil populations, which—given the rarity of that element on Earth—leads him to theorize that the extinction was caused by an extraterrestrial impact. This iridium layer is traced across the globe, and the crater matching it is found at the Chicxulub site in Mexico.
Logistics: If you head past the wall of the city of Gubbio up the Bottaccione Gorge, you’ll find the site of the iridium layer marked in a turnout on the right side of the road. This layer, the K-T boundary—so called because it defines the boundary between the Cretaceous and Tertiary periods on the geologic time scale—will be easily identifiable; it’s been eroded by many a human touch. Reach in to get at the iridium-rich clay layer, and if you’re feeling especially inspired, bring along a hand lens and rock hammer to look for evidence of the extinction; you should be able to see forams in the layers beneath the boundary (the Cretaceous layers) that are no longer present in the layers above (the Tertiary). Afterwards, stop by the Osteria del Bottaccione, on your right as you head back down the road towards Gubbio. It was here that Walter Alvarez, one of the geologists who discovered the iridium layer, held a famous conference of scientists to discuss the layer and its implications. Enjoy some of the regionally famous crescia bread and vin santo dessert wine as you look through the log of the historic meeting, which the restaurant keeps on hand for geology pilgrims. Finally, take some time to explore Gubbio itself; it’s said to be the most beautiful medieval town in Italy, and the view from Piazza Grande alone is enough to make it believable. Plus, there’s no need to worry about abandoning your geology theme as you wander the cobbled streets; the city itself is crafted on and from the mountains.
[Note: The K-T boundary is now officially known as the K-Pg (Cretaceous-Paleogene) boundary, as the Tertiary Period has been renamed, but the layer is still often referred to as the K-T for tradition’s sake.]
The view from Gubbio's Piazza Grande.
The Frasassi Caves (Grotte di Frasassi)
Space: Genga, Province of Ancona, Le Marche
Time: ~.781 mya - present
Imagination: As you step into the Abisso Ancona, the main cave of the Grotta Grande del Vento system, it takes your breath away. The colossal void could comfortably accomodate Milan's famous Duomo. It dwarfs your tiny frame, stretching up and away until nothing can touch it but shadows. In the distance, hulking clusters of stalagmites with floodlights at their feet tower over the footpaths like frosted trees. You’re inside the mountain, surrounded by the Calcare Massiccio limestone, which formed at the bottom of the sea millions of years ago. As the Apennines rose, the limestone was uplifted, pushed from the sea into the core of the mountains. Sulfidic waters permeated faults in the formation and upwelled beneath the water table, meeting the carbonate ground water and producing sulfuric acid, which then began to eat away at the stone, forming caverns. As the cave-bearing limestone continued to be uplifted over time, new, lower rock reached the level of the water table, where cave formation occurs. Through this process of formation and uplifting a number of different cavern levels were created, with older caves higher up in the mountain, having been pushed up and away from the corrosive environment at the water table. Cave formation continues today, but it’s far too slow to see in action; much more striking are the fully formed caves around you. You venture into the surrounding passages, which are less staggering than the main cavern but just as wondrous. They’re entirely coated in speleothems, precipitate formations like stalactites, stalagmites, and flowstones (sheet-like deposits). There’s an ethereally lit cave pool with a speleothem column that resembles an upright Tower of Pisa. There are places where the path ventures over abyssal drops. Occasionally delicate sheets of precipitate hang from the ceiling like drapes, so thin you can see a glow through them and can almost imagine them fluttering in a subterranean breeze. It’s an eerie, enchanting world, and when you make your way back out into the sunlight, your memory of the vast alien realm hidden within the mountain before you seems unreal.
Logistics: The caves can be reached by car on autostrada A14 from the Ancona Nord exit or on superstrada SS74 from the Genga exit. They are located at the Genga-San Vittore Terme train station on the Ancona-Roma line. Adult entrance tickets are 15,50 €, students and seniors are 13,50 €, and children are 12 €.
The gypsum outcrop on Mezzavalle Beach.
Monte Conero and the Messinian Salinity Crisis
Space: Monte Conero and Mezzavalle Beach, just south of the coastal city of Ancona
Time: ~5.96-5.33 mya
Imagination: You pick up a bottle of Rosso Conero from a winery on Monte Conero and open it on the nearby Mezzavalle Beach, taking a moment to appreciate the fact that the geologically influenced microclimate and clayey-sandy silt of the region combined perfectly to produce the Montepulciano wine grapes whose fermented juice you’re enjoying. You lean back on a rock and take in the scene. You wouldn’t know it from the healthy state of the sea today—the lilting, blue-jade surf looks increasingly set on engulfing your outstretched toes—but about six million years ago, the Mediterranean evaporated almost entirely. Tectonics—which jostle the puzzle-like plates that cover Earth’s surface—effectively pushed the African plate into the European one, sealing what’s now known as the Strait of Gibraltar. This cut the Atlantic Ocean off from the Mediterranean, which combined with dry conditions to cause the sea to evaporate. During this time, the Nile catapulted into the desiccated basin, eating away at its own delta to form a yawning canyon, now hidden by sediment. Animals from Africa were able to migrate into the area vacated by the water, and some were then stranded on islands when the sea level rose once more, causing, for example, the evolution of pygmy hippos. Evidence for this salinity crisis sits right behind you: a beautiful outcrop of gypsum, a rock that forms through evaporation. The Mezzavalle Beach outcrop speaks not only to the state of the Mediterranean at the time but to the climate and behavior of the Earth. Distinct strata can be seen in the outcrop, with broad stretches composed of a dark black layer topped with a lighter brown layer. This dark-light transition is presumed to reflect changes in production due to the Earth’s precession, or the wobble of its axis, with darker layers brought on by increased deposition of organic matter. Thin light and dark banding within the larger light brown layer is thought to indicate changes in production due to annual climate variation. So you’re not just looking at a rock; you’re looking at a six million-year-old climate record.
Logistics: Rosso Conero can be found at wineries across the slopes of Monte Conero. Mezzavalle Beach is just north of Monte Conero along Via del Conero. Take the path down from the parking lot, and head to the left (north) along the beach. After what seems like far too long (likely made to seem even longer by the staggering number of beautiful beach rocks you’ve been collecting), you’ll see a distinctive brown-black outcrop on your left, clearly lined and brimming with crystals.
Monte Conero and the Adriatic from Mezzavalle Beach.
As this leg of your journey through space, time, and imagination comes to an end, you can see Monte Conero, the easternmost, youngest peak of the Apennines, to your right, and before you lies the Adriatic Sea. Under the sea, the Adriatic plate is subducting at an infinitesimal rate beneath the European plate, continuing to create the Apennines. Hopefully by now—whether it was touching a bit of the meteorite that killed the dinosaurs, marveling at stalagmites in the heart of a mountain, seeing crystals formed at the bottom of a dry Mediterranean, or the wine that did it for you—you have a new appreciation for the world around you in every dimension imaginable.