Following the Oxfordian stage the laying down of limestones continued across the Bassin Parisien during what we call the Kimmeridgian stage. This stage is named for the village of Kimmeridge in Dorset, on England’s ‘Jurassic Coast’, a region rich in fine limestone cliffs which yield many fossils. It was here that the Kimmeridgian stage was initially defined.
The Kimmeridgian is of great importance to modern human society not just through its relevance to wine (as if that wasn’t enough). It is also of great significance to the petrochemical industry, as Kimmeridge clay, which is found throughout Europe, is the source rock for North Sea oil. The reason wine drinkers know the term, however, is because Kimmeridgian limestones, marls and clays are found beneath some of France’s most exciting wine regions, including Champagne, Chablis and of course the Loire Valley.
As I indicated in my introduction to the geology of the Central Vineyards, the Kimmeridgian stage lasted from 157 until 151 million years ago. This is a much broader time period than the contribution from the Oxfordian stage which, as far as the rocks of Sancerre and Pouilly-Fumé, are concerned, are mostly about 157 million years of age. While the Oxfordian stage is divided into a multitude of different strata, the carving up of the Kimmeridgian rocks in this region is, by comparison, surprisingly straightforward. Despite there being 6 million years of rock deposition to deal with, there are just a handful of layers of significance to vignerons and wine drinkers. And these are rocks with which it is essential to get to grips; the Kimmeridgian limestones and marls of Sancerre, Pouilly-Fumé, Menetou-Salon and beyond are some of the most desirable of all the region’s terroirs.