by Richard Fink, former Vice President – Technical (retired),
Global Ferroalloys at Cliffs Natural Resources
Beer and geology are intimately intertwined. Everyone knows that geologists have a long history with beer and consume it in copious quantities. No good field trip, geologic symposium, or Friday afternoon bull session ends without a refreshing brew (or two).
What most people do not realize is that the type of beer brewed is highly dependent upon area geology. Think about regions known for certain beers. The refreshing bitterness of an English pale ale, the clean light taste of a Czech Pilsner, or the dark, almost burnt graininess of Irish stout are tributes to the power of geology. Beer is more than 90% water, and the geology through which the water percolates makes all the difference in the brew.
Dissolved minerals in water can make a beer outstanding or undrinkable. There are four cations in water that are particularly significant for the brewing process—calcium, magnesium, sodium and potassium. For example, calcium is critical for yeast to work effectively. It also controls the pH of the mash and aids with coagulation and flocculation. Hence, distilled water won’t work for beer. In general, areas with softer water produce lagers and darker ales, while those with harder, mineral-rich water are more conducive to paler, hoppier ales.
Beer beginnings
The fact that certain beer styles are best brewed from certain types of water was discovered by trial and error long before an understanding of water chemistry developed. Monks in Burton-on-Trent in the UK began brewing beer in the 6ᵗʰ century from well water drawn from the evaporite-rich, Permo-Triassic sandstones outside of town. These waters had a pH of 5 to 5.5, ideal for extracting sugars from malted barley steeped in warm water, an important step known as mashing.
Such hard water, high in calcium and sulfate (295 ppm calcium, 300 ppm bicarbonate, 725 ppm sulfate), brings out the bitterness typical of classic ales and helps prevent spoilage. Sulfate enhances the flavor of hops and its preserving characteristics allowed the beer to survive shipping, even as far as India, hence the name ‘India Pale Ale’, or IPA. You can thank the gypsum, and geology, for that. Even so, many still believe the myth that the high hops content of IPAs accounts for their longevity.
The development of lagers
A new style of beer called lagers later developed in continental Europe. While ales are brewed at room temperature, lagers are fermented at chilled temperatures. Lager, from the German word lagern meaning ‘to store’, is a beer that goes through a period of cold storage as part of the brewing process. Before the advent of refrigeration, brewers took advantage of caves for lagering purposes.
The ionically depleted, soft water of the Pilsen region in the west of the Czech Republic (7 ppm calcium, 3 ppm bicarbonate and virtually no sulfates) resulted in the development of the light, clean-tasting lager now known as a pilsner. The metamorphic rocks underlying Pilsen allow groundwater to move through fractures, but few minerals are dissolved in the process. Regions dominated by sandstone and Palaeozoic or Precambrian metamorphic rocks have waters with low contents of dissolved minerals and ions. This often causes the resultant beer to have a less distinctive flavor. As a result, it has to be fermented a longer time, which also increases the alcoholic content.
Porters and stouts
Porter was first developed in 18ᵗʰ century London from water high in calcium and carbonate and low in sulfate and chloride. In areas dominated by carbonate rocks, with springs high in calcium and magnesium, control of the pH in the water and mash is a major issue. The low pH water makes only relatively sweet beers possible. Porter was exported to Ireland where, in 1759, a Dublin brewer named Arthur Guinness began to make a thicker, or stouter, porter with water from Dublin (115 ppm calcium, 319 ppm bicarbonate, 53 ppm sulfate). His brew became known worldwide as stout.
Flowing through 300-million-year-old limestone, the Dublin water is very alkaline and requires even more roasting of the barley, resulting in what is called black malt. Even then the extraction isn’t very good, with the resulting beers having a distinctive grainy flavor and a dark, even black color. This yields the distinctive taste of Guinness and other Irish stouts. There is possible merit to the pub legend that Guinness brewed in Dublin tastes different from Guinness brewed in London. Although the brewing waters of both are high in carbonate, the limestone source rocks of the Irish brewing waters are Lower Carboniferous, while those of the London brew are Cretaceous Chalk. Different levels of magnesium, chlorine, sodium and potassium account for the sweeter taste of the London variety. Guiness consumed in the UK definitely tastes superior to the brew we get in North America.
In Germany, the Reinheitsgebot (Beer Purity Law) is the collective name for a series of regulations limiting the ingredients in beer. The basic law states that only malted grains, hops, water and yeast are permitted. Brewers are forbidden from chemically treating their water and, as a result, the German beer market has been dominated by pilsner-style beers.
For example, Munich’s water supply is not ideal for brewing beer. It is too alkaline, drawn from aquifers in calcium carbonate-rich sand and gravel washed down from the Alps. Their trick is to roast the malt a little to release phosphates from the barley. This increases the acidity just enough to get it into the proper pH range and yields a darker beer.
Paulaner Brewery makes its beers with naturally soft water drawn from Munich’s protected underground wells. These wells drill more than 700 feet (213.4 m) down into the tertiary layers of the foothills of the Alps. This water has been underground and untouched for as long as 12 000 years. ‘Our water is naturally filtered through the earth’s rock, so it doesn’t need additional filtration to remove carbonates,’ says Martin Zuber, Paulaner brew master. ‘We do put it through ion exchange to reduce sodium. The result is extraordinarily soft water with a perfect pH level for brewing almost all beer styles.’
With the availability of malted barley, hops and yeast from all around the world, water is often the only local ingredient in beer. But here too, geology plays a role. Regions most suitable for growing barley and hops are fertile, well-drained volcanic soils. More than 70% of American hops are now grown on the deep alluvial soils of the Yakima and Willamette Valleys of Washington and Oregon, which are derived from the nearby Cascade volcanic uplands.
While geology has a strong influence on beer, it is also true that beer has had a major influence on geology, especially in the field. Geologic mapping is a type of storytelling, rooted in observation, but requiring a lot of imagination and creativity. The crafting of these stories involves the kind of free-wheeling sharing of ideas and analogies that is facilitated by a few beers. But no matter what, the strongest connection between geology and beer is the love that geologists have for it.
Although drawn from a variety of sources, articles and work by Drs. Alex Maltman and Lisa A. Rossbacher deserve kudos.
For more information: Get in touch with Richard on LinkedIn
