The Giro and The San Pietrini

Wow! Yesterday was a stunning end to the Giro d’Italia, one of the world’s great bicycle races. And the excitement occurred because of stone, the legendary San Pietrini cobbles of Rome. With just under 1000 meters to go in the time trial, race leader Denis Menchov looked like he was ready to win not only the overall race title but also that day’s race, the last leg of the Giro.

But then Menchov’s front wheel slipped out from under him and he went tumbling at probably 50 km/hour. The thin tire couldn’t grip the hard lava stones, which come from outcrops near Rome. These are the stones I wrote about in a previous post that Vitruvius described as hard and enduring. Many reporters described them as icy smooth because of the rain. Locals call the cobbles, “San Pietrini,” little Saint Peters, playing on St. Peter’s role as the rock of Christianity.

I have an update to add on this blog. Marie Jackson, who has written extensively about the stones of Rome, has told me that the San Pietrini stone comes from the Capo di Bove lava flow, 277,000 +/- 2,000 years old. The lava erupted from the Faete peak of the Alban Hills volcano, southeast of Rome. Stone comes from a quarry near the Ciampino airport.

(Photo of the cobbles from VeloNews.
To see a video of the fall, you can watch this YouTube link.)

As Menchov fell, you could see him reaching out for his bike as he slid 10 meters along the San Pietrinis. Fortunately, his mechanic was in a car right behind him, and he leapt out of the car, yanked a spare bike off the top, sprinted to Menchov, and had him back riding within seconds. It was stirring and stunning to watch Menchov recover and ride to victory. Although it was exciting to see such a focus on building stone, I am glad they were not culprit that took away a well deserved victory by Dennis Menchov.

Cobblestones Again: Europe

Several weeks ago, my blog about Seattle cobblestones generated a bit of interest so I thought I would follow up by discussing a few old cobblestone roads from Europe. I am using the term cobble a bit loosely, as technically it refers to a stone ranging in size between 64 and 256 millimeters. Furthermore, cobbles typically are rounded due to ice or water. In this context, a cobble is a stone used as a paving material.

My favorite are the gray cobbles used throughout Rome. Locals call the three-inch-square paving blocks, “San Pietrini,” little Saint Peters, playing on St. Peter’s role as the rock of Christianity. In his landmark De Architectura, or The Ten Books of Architecture, Vitruvius referred to the lava that made the stones as hard, enduring rock, calling it siliceae, or silex.

San Pietrini in La Piazza del Popolo, Rome

More exotic cobbles are found in Seravezza, one of the great localities for marble in Italy. It was here around 1519 that Michelangelo went in search of white marble for the façade he had designed for the church of San Lorenzo in Florence. The church was never built but Michelangelo did open up quarries still used at present. In the sidewalks of Seravezza, you can find a wide variety of the many colors of marble quarried in the Apuan Alps.

Marble paving stones of Seravezza

In the town of Volterra, about 30 miles southwest of Florence, are massive paving stones. Volterra is a classic Tuscan hill town with a history that stretches back to Etruscan times. The Etruscans built several gates, one of which remains and still has figures carved out of basalt, though much weathered. The well-worn roads are made of sediments rich in fossil shells, the largest of which are the size of a deck of cards.

Shells in the road of Volterra

I have not visited my final site of European cobbles. I learned about it from Michael Welland, who writes the blog, Through the Sandglass. Here is what he had to say about the old French Mediterranean city of Narbonne. “Awe-inspiring, the oldest cobbles are the pavement of the great road of the Roman Empire (Narbonne was a major regional capital), the Via Domitia. This section of the road was uncovered not that long ago in the town square. This is really hairs-on-the-back-of-your-neck stuff as you gaze at the wear of traffic 2000 years ago.” He thought they were highly indurated marbles.

Via Domitia (photo courtesy of Michael Welland)

Good Old Cobblestones

President Obama has said that his stimulus plan will provide the “largest investment increase in our nation's infrastructure since President Eisenhower created the national highway system half a century ago.” It will create hundreds of thousands of job for people rebuilding railways, bridges, and roads. While I applaud his concern about jobs and improved safety, I worry that in the mad rush to pave we may lose a bit of history—the handful of cobblestone roads still dotting Seattle.

A happy group of explorers trodding across one of Seattle's last cobblestone streets

Between the 1890s and 1910s, sandstone cobbles were a a popular road-paving material in Seattle. The most commonly used varieties came from quarries in Wilkeson, a small town about 45 miles south of Seattle. Workers could easily cut the brick-sized blocks, which provided good traction for horses, although horse shoes did wear down the stone. And the stone cobbles lasted longer and created less of a mess than the mud or wood of the past. (Manhattan also has a few cobblestone streets made from the 450-million year old Quincy granite.)

Quincy Granite cobblestones in Greenwich Village

The Wilkeson sandstone lithified from thousands of feet of sand deposited 40 to 50 million years ago in the Eocene Period when western Washington was flat and subtropical. Palm trees, swamp cypresses, and tree-sized ferns grew in the moist (40-100 inches of rain), bayou-like environment. Waves from an ocean that spread to the west washed ashore on beachfront property, now covered by the urban metropolises along Puget Sound. The only mountains that existed rose far to the east along the Washington-Idaho border. Rivers and streams washed out of those mountains and dropped sand in a coastal lowland dotted with seasonal lakes, swamps, and lagoons.

In addition to sandstone cobbles, brick was another important paving material and can still be found on a few Seattle streets. Local manufacturers used a clay deposited in a proglacial lake, which formed in advance of the ice sheet that covered Seattle during the last Ice Age. A production capacity of 70,000,000 bricks a year made King County the largest producer of paving brick in the country. At one time, these bricks covered streets in Portland, San Francisco, Tokyo, and Los Angeles, as well as roads in Chile, Argentina, and India.

One other local building material, the Index granite, appears on local streets. It formed 34 million years ago during subduction of the Juan de Fuca plate under the North American continent. The Index was used primarily for curbs and can still be found in a few older neighborhoods of Seattle. (One way to get a feel for the age of a neighborhood is to look at the curbs. Old ones are granite; newer ones have concrete with a metal rim, particularly on corners; and modern ones are only concrete.)

According to the last official survey I could find, conducted in 1993, only 93 of these historic streets remain in Seattle; most have been paved over, their stories lost to drivers who don't want the jarring ride. I do not mind them. I like the connection to the past and consider it a privilege to drive over the ancient cobbles and rustic bricks, although I try to take these roads when no else is in the car with me.