We all know geology – and quarrying – contributes enormously to our infrastructure and our lifestyles. As Bill Langer explains, geology also plays a crucial role in the fermentation of one of life’s other great necessities.
I recently came across an article I wrote about eight years ago (“N is for non-metallic”, Quarry 19:10, October 2011) stating that diatomite was used to filter beer.
That brought to mind a TV ad from the 1960s for a beer brewed in Rochester, New York. A man finished drinking the beer, went “ahhhh”, put the can to his ear like a seashell and said: “The beer is all gone, but I can still hear Hemlock Lake.”
There was more to the ad than just a clever gimmick. The quality of beer is defined in part by its ingredients, the major ingredient being water – and geology strongly influences the quality (especially the chemistry) of water.
The beer in the ad was brewed with water from Hemlock Lake. It is one of the lesser Finger Lakes in New York State, located about 56km north-north-east, as the crow flies, from where I grew up. Hemlock Lake is underlain with, and surrounded by, Devonian age shales and siltstones. Those rocks commonly contribute very few minerals to the water.
Consequently, the water from Hemlock Lake tends to be free of minerals and very low in bicarbonates. It probably would be similar to the water of Pilsen, a city in the Czech Republic. That city is known worldwide for its pilsner beers, which are medium-bodied and are characterised by high carbonation. It is no surprise, then, that one of the beers brewed with Hemlock Lake water is a pilsner.
If you go to the town of Burton-upon- Trent, north-west of London, England, brewers use water from springs with rocks containing gypsum. The gypsum brings out the flavour of the hops. Some brewers add gypsum to water to enhance flavour. This is known as “Burtonisation”.
The water in Munich, Germany, is drawn from aquifers that lie in calcium-carbonate-rich sand and gravel washed down from the Alps.
Unfortunately, it is too alkaline to make good beer. To overcome this problem the brewers roast the malt, which releases phosphates from the barley. The phosphates increase the acidity just enough to get the brew into the correct pH range, resulting in a slightly different-tasting, dark beer.
Dublin, Ireland, sits on 300 million-year-old limestone, and its water is even more alkaline than Munich’s. Brewers in Ireland roast their barley even more than in Munich, resulting in what is called “black malt”.
In 1759 a Dublin brewer named Arthur Guinness began to make a thicker, darker beer with water from Dublin and black malt. His brew became known worldwide as stout.
Not only does geology affect the flavour of beer, some geologic features – caves for example – also impact the flavour. Some of the water in central Europe lacks essential elements for the brewing process, which may result in a beer with a less distinct flavour. To compensate for this, the beer has to ferment for a longer time – preferably in a dark, cool environment like a cave. The word “lager” is German for “warehouse”; hence the name “lager” is given to classic beer from central Europe that is stored in caves used as lager.
Nowadays many breweries create their own customised water. Undesired elements are filtered from the natural water and desired elements are added back to the brewmaster’s recipe, guaranteeing a tasty beer.
To that I say: “The geology is all gone, but I can still hear the rocks.”