I’m no geologist.
It strikes me as one of the least interesting occupations around to be honest. Far less interesting than even accountancy.
In fact rock doesn’t interest me much at all whether it’s on the radio, the sticky sweet pink stuff with ‘Blackpool’ written inside it or the hard things on the ground that were formed millions of years ago for the purpose of stubbing one’s toes on while wearing flip flops.
But, this being the world of wine, I’ve had to pay attention. I know things such as loess is windblown soil and, better yet, I know the names of different sedimentary soils IN FRENCH. Care for an erudite discussion about the benefits argile-calcaire imparts to Pinot Noir this weekend?
So I’ll forgive you for not finding the title of this post the sexiest, most captivating thing ever. I understand, I probably wouldn’t read it either.
However I do understand that many of the world’s best vineyards for Riesling production look like a kind of smashed up roof tile depository. Blue, grey and occasionally red slates coat the ground under the vines in such illustrious vineyards as the Scharzhofberg, the Wehlener Sonnenuhr and the Erdener Pralat. It must mean something.
Firstly the the loose structure of the slate top soil allows the vine to take root in perilously steep sites. the cracks and fissures underneath that topsoil ensure a tight grip. Which is just as well when you consider what is reputedly the world’s steepest vineyard, the Bremmer Calmont, angles up at around 75-80% gradient.
Secondly the slate helps retain moisture. While the Mosel is the coldest growing region for vines in Europe on average it does have hot summers and autumns. With the steepness of slope any other type of soil would be quickly eroded and the rain water reserves would run off.
Thirdly slate seems to act as a heat conduit, radiating warmth through the day and into the evening helping the grapes to achieve ripeness that the climate suggests shouldn’t be possible.
One thing slate doesn’t do is impart the ‘mineral’ quality that us Riesling geeks all talk about in the wines. Vine roots don’t literally suck up stone particles and put it in the grapes. Even so Riesling grown on top of slate tastes different to Riesling grown on top of other rock types such as volcanic basalt or granite. But that doesn’t make geology any more interesting so watch this brilliant Two Ronnies sketch about being boring instead.
By Colin Thorne