Why Are Tiny Fossilized Oysters Buried in a Vineyard's Soil? — Chablis

Walk through the vineyards surrounding the village of Chablis, at the northern edge of Burgundy, and you may notice small, swirl-shaped fragments mixed into the pale soil. Pick one up and look closely, and it turns out to be the fossilized shell of an ancient oyster. Why would the soil of a vineyard hold the fossils of creatures that once lived in the sea? The answer lies in the fact that, roughly 150 million years ago, this land was the floor of a warm, shallow sea.

A Land That Was Once the Floor of the Sea

The soil beneath the Chablis vineyards belongs to a geological layer known as the Kimmeridgian. Roughly 150 million years ago, this area was not yet part of the continent — it was the floor of a warm, shallow sea. Over a long span of time, carbonate sediment from that sea, together with the shells of countless small creatures that lived in it, settled into a clay-bearing limestone layer that still lies beneath the vineyards today. Among the fossils found most often are small, comma-shaped oysters known by the scientific name Exogyra virgula. Even now, when the soil is turned, these fossils still surface.

The Monks Who Extended the Vineyard

It was the Abbey of Pontigny, in the 12th century, that gave a major push to vine-growing on this land. The monks of this abbey, part of the Cistercian order, cleared the slopes of the surrounding hills and planted vines parcel by parcel, extending the Chablis vineyard. They are also said to have built a building in the town of Chablis for making and storing wine, known as “Petit Pontigny,” part of which still stands in the town today.

The Part of Burgundy Closest to Paris

Burgundy is made up of a string of wine districts, and Chablis sits at the northernmost point among them — said to be the part of Burgundy closest to Paris. Look for Chablis on a map, and it sits closer to the Champagne region than to the Côte d’Or, where Burgundy’s main wine districts are clustered. From the medieval period into the early modern era, Chablis wine is said to have traveled down the Yonne River and on through the Seine, reaching all the way to Paris.

A Vineyard That Nearly Vanished, and Came Back

The Chablis vineyard did not arrive at its present state without hardship. In the late 19th century, phylloxera and powdery mildew struck the vineyard and caused serious damage. Grafting gradually helped rebuild it, but hardship continued into the 20th century. A major frost in 1957, in particular, is said to have caused serious damage to the vineyard. In 1955, in the years just after the Second World War, the vineyard’s total area had shrunk to 550 hectares. From the 1960s onward, as mechanization spread and technology for protecting vines from frost became available, the vineyard slowly but steadily reclaimed its lost ground. As of 2024, the total area of the Chablis vineyard stands at roughly 5,866 hectares.

Three Facts Worth Knowing

• Beneath the Chablis vineyards lies a layer of soil that was once the floor of a sea, roughly 150 million years ago. That soil still holds small, comma-shaped fossilized oysters known as Exogyra virgula.
• In the 12th century, monks of the Abbey of Pontigny cleared the hillsides of Chablis and extended its vineyards. They also built a building for making and storing wine known as “Petit Pontigny,” part of which still stands in the town today.
• Phylloxera in the late 19th century, followed by repeated frosts in the 20th, once shrank the Chablis vineyard dramatically. After mechanization and anti-frost technology spread from the 1960s onward, the vineyard revived, and as of 2024 covers roughly 5,866 hectares.

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