Giro d’Italia and Carrara

In honor of the Giro d’Italia ending in Carrara today, here’s a take on the town. I first saw Carrara and its quarries from a car window, while I was driving north out of Pisa. My wife, a couple friends, and I had stopped in Pisa to look at the Leaning Tower but left after about 45 minutes. It’s not made of Carrara marble and the commercialization was offputting. I didn’t need to buy boxers with Leaning Tower located in a prominent place.

We were about 25 miles or so from the green foothills of the Apuan Alps. Broken clouds created a pattern of shade and light punctuated by several bright white splotches. Earlier I had read guidebooks that explained that “No, that isn’t snow, it’s marble,” so I knew I was seeing the Carrara marble. I was quite giddy at seeing it, but as we drove closer to town my excitement began to fizzle. Where were the charming old buildings? Quarries had been worked in these mountains more or less continuously for the past five centuries and I expected quaint structures made of the local stone. Instead, the road felt like many other industrial/shopping mall districts I had driven by, with warehouses, car dealers, and restaurants creating a monotonous blur of banal buildings. I enjoyed seeing all of the stone mills, each with stacks of marble blocks, pallets of sliced stone slabs, and massive cranes for ferrying the stone, but they looked like any stone mill I had seen in my previous travels.

Finally, as we drove closer to the mountains the wide, industrial street gave way to a confusing maze of narrow, often one-way, poorly marked roads. After circling around, getting lost, backtracking, and hoping we knew where we were, we crammed our little rental car into a spot along a lane about twice as wide as our car. A typical Carrarese building, a four story, plain stucco-covered structure, stood about two feet from my front door. On the other side of the road, and twenty feet below us in a concrete-sided trench, ran the Torrente Carrione, Carrara’s couple-inch-deep trickle of a stream.

Abandoning the car, the four of us wandered toward where we thought our bed and breakfast might be. The streets closed tighter, eventually getting too narrow for cars. Above us rose canyon-creating buildings, many with windows festooned with drying laundry and hanging planters. Not every building was made from marble, but I had no doubt we had entered a hub of the marble universe. Not that the locals respected their great stone; graffiti covered many marble walls and several marble statues.

The next morning, I met with Dr. Paolo Conti, a geologist at the Center for Geotechnology at the University of Siena. Paolo had graciously offered to take me up into the mountains to learn more about the quarries and the geology. Getting in his car we drove three miles or so into the Apuans. We parked in a lot next to the Ponti di Vara, a handsome, five-arched, brick-and-marble bridge. Originally, a route for the railroad that crisscrossed the quarries, the Ponti di Vara is barely wide enough for the hundreds of trucks that zip across it each day.

From where we stood, we could look directly up toward the quarries of marble. They glowed a blinding white in the sunlight and had crept half way up Mount Maggiore, which rose 3,000 feet above us. Across the road, yellow signs pointed to several quarries, including the legendary Fantiscritti, quarried since Roman times. Another sign read “Visita la cava in galleria piu’ bella del mondo.” Visit the most beautiful underground quarry in the world.

Pulling out several, very cool and colorful geology maps, Paolo showed us that we were at the base of the Miseglia valley, one of three quarry valleys around Carrara. To the north lay Torano and to the south Colonnata. Each cut back into the Apuans for several miles and each had quarries first operated in Roman times. No one knows how many quarries have pierced these mountains but I have read an estimate as high as 650. One of Paolo’s geologic map from 2000 listed 187 quarries.

Since I wanted to see more of the quarries, Paolo suggested we head up above the next valley north, Torano. After driving for ten minutes or so, Paolo swerved the car across the road on a hairpin turn, and pulled off on a very soft shoulder. His driving seemed like a typical geologist’s, veering abruptly to see rocks, combined with an Italian’s sanguinity at cutting across a blind turn.

“I often bring students here,” said Paolo, perhaps explaining his driving calm. “It’s one of the better spots to see the thick beds of limestone (the 200-million-year old source material for the marble).” We got out, I looked both ways, and crossed the road. Oaks and beeches, some of which had begun to change color, grew out of the gray, massive rock. I had encountered limestone like this before in many places. I called it tearpants limestone, in reference to its sharp, resistant edges. “We haven’t found many fossils in this rock but this is one place we have,” said Paolo. I looked but found nothing other than a few snails crawling across the broken edges of lackluster limestone.

Up and up we drove as the road climbed and wound steadily through the foothills. We passed through zones of pines, under a canopy of rust colored beeches, before stopping near a small lodge, where we hoped to find lunch. Since it was closed we walked across the road and hiked up a trail to the Refugio Carrara, one of the elaborate huts that one can stay at throughout the Italian Alps. We did find lunch there and I got to accomplish one of my goals for the trip.

Over the past few years, a cured pig fat called Lardo di Colonnata has achieved a certain status among epicures, but for Carrara’s cavatori lardo has been a staple of their diet for centuries, a cheap, abundant food that tasted cool and refreshing on a hot day. I knew I couldn’t quarry stone, but at least I could eat like a quarryman. The Carrarese make lardo in their dank basements by curing raw pig fat in a tub of marble. Additional flavor comes from a combination of rock salt, pepper, garlic, and rosemary. Like the cavatori, I ate my thin slice of lardo with onion and tomato on bread. It had a creamy, translucent texture and melted deliciously in my mouth. I followed it with a shot of espresso. Geologizing doesn’t get any better than this.

Energized by pig fat and caffeine, we headed back out to find rocks. Paolo whisked us down the road to a spectacular viewpoint into the Torano Basin, where I could finally get a sense of the scale of quarrying. In the center of the valley, fifteen hundred feet lower and a three quarters of mile away, a ledgy quarry, known as Polvaccio, stairstepped up the valley face. Polvaccio has been worked since Roman times and was where Michelangelo quarried his Pietá block. Getting out my binoculars, I counted 18 ledges of marble, each of which Paolo explained was between 15 and 30 feet thick.

Nearly every inch of the valley walls around Polvaccio had been ravaged by quarries. Road after road zigzagged up the nearly vertical faces, faces covered white in marble by years of quarry debris. The bends on the quarry roads are so sharp that trucks cannot turn and instead back down every other switchback. More roads climbed the valley wall below me, as well as the smaller valleys south and east of Polvaccio. At the high points of the southern and eastern valley ridgelines, quarries had lopped off the summits, creating openings shaped like gun sights. “I remember when there was a mountain there,” said Paolo. The view was one of the most spectacular and disturbing I have ever seen.

Marble Madness and Mayhem

Several weeks ago I received an interesting email from a Danish engineer in regard to my story about the Aon/Amoco/Standard Oil building (Big Stan) in Chicago. He was concerned that I had given a jaundiced picture of marble as a cladding material. “You forgot to write that there are a very, very high number of marble facades performing extremely well in all kinds of climatic zones,” he wrote. He is absolutely correct that the vast majority of buildings clad in marble do not experience the panel bowing problems found on Big Stan. Marble is generally a sound choice, when used correctly.

But in the article co-written by my Danish correspondent, it is also clear that there have been what seems to me an unusually high number of buildings where marble cladding has failed. (Durability of Marble Cladding—A Comprehensive Literature Review, in Journal of ASTM International, v. 4 no. 4, 2007) These include La Grande Arch de la Defénce (see photo below) and SCOR Tower, Paris; Richmond City Hall, Virginia (all marbles panels removed and replaced by steel, painted aluminum, and granite); and IBM Tower in Brussels.

Two buildings stand out for the most notorious warping. One is the 310-foot tall Zagrepcanka tower in Zagreb, Croatia, unaffectionately dubbed “The hells tower,” due to falling panels that led to construction of a tunnel to allow employees to reach the entrance. (The smaller photos are of the Zagreb tower, by Jan Anders Brundin.)

The other is Helsinki’s Finlandia Hall, designed by the great architect Alvar Aalto. Completed in 1972 with 7,000 square meters of Carrara marble, the panels started to deteriorate with bowing, cracking, and spalling. The fine citizens of Helsinki decided to replace the panels and chose to reuse Carrara again. Within six months these new, supposedly ultrastrong, ultrasecure panels began to warp. Curiously, they warped convexly; the original panels warped concavely. To this day no can explain why.

Finlandia Hall in Helsinki, with Carrara marble panels, image from Wikipedia

Building stone has failed across climates from northern Europe to Cuba to Libya to Canada in marble quarried in areas equally as diverse, such as Vermont, Greece, Greenland, and Norway. Carrara marble, however, leads the field, in part because it is the most widely used marble in the world.

In their report, the authors made several observations:

  1. The higher the temperature variations, the higher degree of bowing.
  2. Higher humidity can lead to problems when water penetrates pore spaces.
  3. There is no correlation between panel size and thickness and tendency to bow.
  4. Bowing tends to be more pronounced on the southeast and southwest facades.
  5. More pronounced bowing occurs on the upper parts of buildings.
  6. No link has been found between anchoring system and bowing.
  7. Marble color doesn’t impact bowing.
  8. Pollution doesn’t impact bowing.
  9. At least a half-dozen previous authors have noted that bowing depends on the grain boundaries of the marble, which ultimately depends on the geologic history of the stone.

The authors recommend the development of a series of guidelines to choose, test, and produce marble panels. They conclude that “technically acceptable properties should…have very high priority when choosing a marble type for a building project, whereas today aesthetical properties are often considered as being of greatest importance even though the aesthetic problems will change rapidly for a nonsuitable marble as it deteriorates.” In other words, no matter how pretty and elegant the Carrra marble looked on Big Stan, when they failed, it was a monumental screw up that could have been avoided if the builders had been more concerned with function over style. Once again, it pays to pay attention to geology.