There is one aspect of geology that makes even us mining engineers sit up and take notice, namely the relationship it has with whisky. I edited an article on the subject 31 years ago by Stephen Cribb and Julie Davison (who subsequently married and co-wrote a book in 1998 called Whisky on the Rocks), and as a seminal work bears repeating at this festive time of the year.
The generic term ‘whisky’ includes grain whisky (distilled using a mixture of barley and maize) and malt whisky (produced solely from malted barley and usually derived from a single source). Either way, the distilled alcoholic beverage is spelt ‘whiskey’ in Ireland (based on different translations of the original Gaelic in those countries), and the ‘e’ is also used when referring to American whiskies.
In the United States, bourbon is a whiskey distilled from a mash containing at least 51% corn, and rye refers either to American whiskey distilled from at least 51% rye or to Canadian whisky. Tennessee whiskey (for example Jack Daniel’s) is distinguished from other bourbon in that it is filtered through sugar-maple charcoal after distilling. In North America, whisky from Scotland is often simply called Scotch.
“It sloweth age; it strengtheneth youthe”
Two wonderful quotes about whisky come to mind. “One dram is alright, two is too much, three is too few,” and “It sloweth age; it strengtheneth youthe; it helpeth digestion; it abandoneth melancholy; it relisheth the harte; it lighteneth the mynde; it quickeneth the spirite.” The first is an old saying from the Highlands of Scotland, and the second comes from Raphael Holinshed’s Chronicles of England, Scotland and Ireland. Incidentally, the second edition of this work, published in 1587, is widely believed to have been used by Shakespeare as the source for most of his history plays, for King Lear and also for the plot of Macbeth.
The article by Cribb and Davison, published in December 1990, focused on unblended, single malt whisky. The authors noted that, at the time, with the exception of Bushmills from Northern Ireland, all U.K. single malt whiskies originated in Scotland (note that several single malts, including Teeling, are distilled in the Republic of Ireland).
The Scottish whiskies are traditionally divided into five geographic groups; Highlands, Lowlands, Islands, Islay and Campbeltown. The most famous and concentrated area of malt manufacture is Speyside, a subdivision of the Highland classification, within which over 45 distinct malts were recognised in 1990.
In simple terms, malt whisky is distilled beer. Indeed, several distilleries started in the 19th century as rather unsuccessful brewing operations, and it was only with the introduction of distillation that a nondescript brew was transformed.
An important difference from the brewing of beer is that during the kilning of the barley, when the germinated growth is arrested by heating, peat is used as the main heat source and the peat smoke is allowed to permeate the malt. Two, and sometimes three, distillations of the wort take place in pot stills made of copper, the design of which has varied little since the early days of whisky making.
Cribb and Davison wrote that it is generally accepted that the composition of the naturally-occurring ground waters utilised in the production of the distillable liquor is a major factor in the unique nature of each malt whisky. The chemistry of this water is dependent on the geological horizon from which it has arisen. Consequently, malt whiskies can be examined from a geological rather than a geographical point of view.
Geologically, the oldest of the malt whiskies are the Precambrian Torridonian varieties from the shores of Lochindaal on the west coast of Islay. The Bowmore and Bruichladdich distilleries derive their water from streams crossing coarse grits and arkose sandstones. These smooth, golden coloured, dry spirits compare markedly with the deep amber, full-bodied liquors distilled on the southern shores of the same island. Laphroaig, Lagavulin and Ardbeg utilise waters and seaweed-containing peats from the phyllite metamorphic rocks of the Lower Dalradian. These peats and the characteristic bare and exposed coastal locations of the distilleries result in the unique smoky, iodine-like pungency.
Cribb and Davison wrote that to the south-east of Islay, on the Mull of Kintyre, the renowned Campbeltown malts use water derived from the mica-schists and slates of the Upper Dalradian. Regrettably, the sweet and smoky whiskies of Springbank and Glen Scotia are all that remained (in 1990) from over 30 distilleries.
The full article ran to some 1,300 words, and ended its foray into the geological world of malt whiskies by noting that there are two that draw their water from the volcanics of the Tertiary Igneous Province in the Western Isles. These, said the authors, are the little known but surprisingly pleasing soft, golden and sweet Tobermory from the Isle of Mull, and the highly respected straw coloured, dry and peat flavoured Talisker from the desolate north-east coast of the Isle of Skye.
Cribb and Davison concluded that a “true and full appreciation of malt whiskies can probably only just be achieved in a single lifetime. However, there can be no better way to educate oneself than to line a dozen or so of these fine distillates in stratigraphic order and work from oldest to youngest.” Done enthusiastically, you might also discover whisky’s ability, like those of a mining engineer, to make the earth move.
— Dr. Chris Hinde is a mining engineer and the director of Pick and Pen Ltd., a U.K.-based consulting firm he set up in 2018 specializing in mining industry trends. He previously worked for S&P Global Market Intelligence’s Metals and Mining division.
(This article first appeared in The Northern Miner)