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Gilles Bonnefoy Côtes du Forez Migmatite 2020

Gilles Bonnefoy Côtes du Forez Migmatite 2020

I have no doubt that wine is a mind altering substance. While this statement might seem rather obvious at first, I am not referring merely to the well-described psychotropic actions of alcohol. No, I mean something else.

Thirty years of thinking about, tasting, drinking and generally obsessing about wine has caused me to read much more widely than I would have ever imagined. I have learnt about European history and culture, of its kings and queens (and not infrequently which vineyards they patronised, and which wines they drank). I have learnt about agriculture and the life sciences, everything from the pros and cons of different farming philosophies through to yeast genetics. I have learnt about meteorology, of climate change and its effects, from the relevance of a vacillating jet stream to viticulture to the various types of frost. Perhaps mind-expanding would be a better term than mind-altering, though?

And along the way I have learnt a little geology too, not infrequently aided by wine-drinking geologists who kindly interject when I get something completely wrong. Which is not that rare an occurrence.

Geology is of undoubted relevance to wine style and quality. I have tasted this for myself, so many times, that I would entertain no alternative belief. Every time I find I prefer a Sancerre from Kimmeridgian limestone to one from Oxfordian limestone, or whenever I find myself favouring a Muscadet from vines planted in degraded clay soils over gabbro, to one from a vineyard of sandy gneiss soils, I am reminded of the significance soils and rocks have for wine. Of course, despite having held this belief for decades, I don’t believe we are any closer to understanding all the mechanisms by which rock and soil define the character and quality of what ends up in your glass, but I won’t entertain any notion that the two are not related.

This week’s Weekend Wine comes from a vigneron with an eager interest in his local geology. Gilles Bonnefoy has vines planted on granitic and basaltic terroirs, as do many of his peers in the Côtes du Forez and Côte Roannaise appellations, but he is the only one I have met who has vines on migmatite, a very peculiar type of granite. Or rather half-granite.

 Gilles Bonnefoy Côtes du Forez Migmatite 2020

To understand the origins of migmatite we need to know a little about metamorphosis, the process whereby rocks change their form under sustained pressure. It is what transforms deeply buried clay into shale and then slate, and if the pressure continues, into schist and then gneiss. Keep going and the pressure will eventually cause the rock to melt, creating magma. Migmatite is what results if the pressure is relieved at this melting point, and the rock steps back from the brink; those parts less resistant to pressure have melted and they then solidify, whereas some more resistant parts of the rock may have persisted, unchanged. The end result is a mix of new igneous rock (typically granite) and surviving metamorphic rock (in my example, gneiss).

As you might imagine, this confused early geologists no end; they didn’t know how classify the rock, or how to name it. It was a Finnish geologist, Jakob Sederholm (1863 – 1934) who settled it, diplomatically classifying it as a mixture of both igneous and metamorphic, and it was he who coined the term migmatite, derived from migma, Greek for mixture. As far as I know there are not many examples of migmatite across Europe, but there is some in the Massif Central, in the Côtes du Forez appellation. Here Gilles Bonnefoy has planted some Gamay vines in mica-rich clay over a migmatite bedrock, and this is just one of a number of interesting geologically themed cuvées that he produces (see my recent Loire 2021 report for a note on another of his geological wines, Dacite).

Gilles Bonnefoy works using biodynamic methods in the vineyard and cellars, with certification from Demeter. The fruit for his Côtes du Forez Migmatite is picked by hand and vinified in whole bunches, the sugars fermented by indigenous yeasts. He does not chaptalise, uses the minimum dose of sulphites possible, and he bottles the finished wine without any filtration after a relatively short élevage. In the glass the 2020 shows a vibrant cherry red hue, with a good depth of colour at its core, wrapped in a crimson rim. The aromatics are complex and include some of the darker elements that make Gamays from this region so appealing (and which surely relate to the region’s soils?), the smoked and crushed red cherry stone laced with toast, liquorice and black tea leaf. The palate that follows feels supple and tightly framed, with bright acidity and a fine tannic grip. Smoky and textural, compact and delicately grained, with some real grip in the finish, this is a delicious and very drinkable delight. I would advise drinking now, or over the next few years, to see it at its best. The alcohol is 13.5%. 92/100 (4/7/22)

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