It's not just wine that benefits from great terroir. Scotland's peat soils, sea air and heather all contribute to malt whisky's flavour, writes MICHAEL JACKSON

It’s not just wine that benefits from great terroir. Scotland’s peat soils, sea air and heather all contribute to malt whisky’s flavour, writes MICHAEL JACKSON

The grape and the grain have one of those relationships where one partner does all the talking. She chooses the language, too: French.

Mademoiselle Vinifera is sunny, blushing, plump and juicy. She is lusted after by connoisseurs who fall for her charms. But grapes are not the only fruit, and not all great drinks are made from grapes. The grain is its other half.

In contrast to the grape, the ear of barley looks spiky, yet handsome. Perhaps if it were more vulnerable, barley might be more prized. But with its angular looks, resilient constitution, and sufficient adaptability to live in a broader belt of latitudes, it is, instead, taken for granted.

The grape and the grain live next door to one another in temperate Europe. The grape prefers the temperate-but-warm countries north of the Mediterranean; grain the temperate-but-cool countries north of the Alps. At the north-western extreme of barley cultivation lies Scotland.

Among brewers and distillers, the most basic division on barley is between those who favour ‘continental’ varieties and those who prefer ‘maritime’ strains. The former are said to provide a creamier, richer, cleaner, result; the latter to gain crispness and freshness from the sea breezes.

Britain cultivates maritime varieties. The hills and rivers that form the border between England and Scotland give way to rolling countryside. The borders, Aberdeenshire, the Laich of Moray and the Black Isle are Scotland’s principal growing areas. Against the grain

Grain takes up too little water to yield its own juice. The grains have to be steeped in water until they begin to sprout. This sprouting is then arrested by kilning, at which point the grain has become malt: crunchy and nutty, and ready to yield its fermentable sugars. Yet more water is required for this process, in a vessel which works like a coffee filter but is known as a mash tun.

’It’s [all in] the water,’ was about all I could glean when I first began to ask questions about Scotch whisky 30-odd years ago. ‘It’s the geology, stupid’ might be more fundamental. Geology as a discipline is considered to have begun in Scotland, with Dr James Hutton’s book Theory of the Earth, published in 1788.

Much of Scotland’s diversity arises from a spectacular collision 400–500 million years ago. Scotland was at that time attached to North America. It was in collision with a European plate that included England, Wales and Ireland. The geological turbulence continued until 20,000 years ago, when Scotland came to rest. It abounds with corries (hollows in the mountainside); lochans (small lakes) and lochs in a wide range of sizes – sometimes stretching for many miles, possibly with a small opening to the sea; straths (broad valleys) and the glens (narrower valleys) that appear on every other whisky label.

Distilleries high in the mountains claim the cold weather assists their condensers, and makes for a clean, creamy, spirit. The highest, all at just over 300m, are Braeval, Dalwhinnie and Tomatin. The mountains provide snowmelt too, but what kind of rock does it filter through, and for how long? And when it emerges in a spring, does it flow over peat or heather, for how long?

In 1990, geologists Stephen Cribb and Julie Davison made a study of rock formations in Scotland’s whisky regions, and compared them with tasting notes by myself and other authors. Their findings, in Whisky on the Rocks, suggested that the similar tastes in certain whiskies produced near each other might in part be due to the similar rock from which the water rose. The oldest rock is that which supplies water to the Bowmore and Bruichladdich distilleries on Islay, off the west coast of Scotland. It was formed about 600–800 million years ago and seems to contribute an iron-like flavour. Large parts of Islay are also covered in peat. As the water finds its way to the distilleries, it picks up peaty flavours. Closer to the shore, the land is salty and seaweedy. These flavours and aromas are evident in the steeps and mash tuns.

The peat has even more influence when used to fuel the malt kilns. Some scientists argue that salt is lost in distillation. If so, it returns when whisky is matured in earth-floored warehouses washed by the sea, such as those at Ardbeg. A modern maltings on Islay supplies all of the distilleries to varying degrees, but two also make a proportion of their own malt: Laphroaig and Bowmore. Each takes its peat from a different part of the bog, with slightly different results. Highland Park obtains different results again, with its local peat on Orkney.

Granite is the principal rock of the Grampians, the group of mountains and sub-ranges that dominates the Highlands, and from which the river Spey flows. In looking at the Grampians, Whisky on the Rocks identifies Ben Rinnes and the Conval Hills as sources of the typical Speyside water, feeding distilleries such as Glenfarclas, Aberlour and Craigellachie. The study points out that the region’s geology is diverse, embracing substantial areas of limestone and sandstone.

Does heather also influence flavour? Some Speysiders, famously Balvenie, have an extraordinary heather-honey note. If it’s not from those purple hillsides, there is a powerful mimic at work, perhaps in the yeast or in the maturation.

Mineral flavours and textures seem evident in some malt whiskies. I believe the mineral content of the water influences the extraction of malt sugars. Not only is water a potential influence in the steeping and mashing, it is also used to reduce the strength of spirit in the cask to aid maturation. It is further employed to reduce mature whisky to bottling strength. The last stage is influential only in the handful of distilleries that bottle on site (and in those cases, very influential). They were, until recently, Glenfiddich, Balvenie and Springbank. Earlier this year, Bruichladdich added what might be termed a boutique bottling hall.

Someone once tried to market Islay water, but the ironstone and peat colours put off the punters. Too much terroir, apparently.

Michael Jackson is author of The Malt Whisky Companion (£12.99, Dorling Kindersley) and Scotland and its Whiskies (£16.99, Duncan Baird Publishers).

Written by Michael Jackson