GEOLOGY OF BEER 81 the town of Pilsen (Table 1) in Bohemia (now in the Czech Republic) A critical process was the storage of the fermented beer in cold caves – lagering – and thus two new terms were introduced into the brewing vocabulary, pils and lager This direct response to brewing with waters of low ion content spread rapidly in the 1880s throughout those areas of northern Europe where such waters are common This included the Netherlands, Germany, and Denmark, where to this day lager is recognized as a major beverage So far, no mention has been made of another important brewing nation, and that is Belgium The country is fascinating, as geologically it is not always very promising as far as brewing waters are concerned, but it illustrates a classic example of a unique response Simply, in areas where there are useful mineralized waters, use them to their best effect; otherwise, ignore the rules In East Flanders, particularly around Oudenaard, there are carbonaterich waters, and the characteristic Brown Beers are top-fermenting, dense, and smooth These contrast markedly with the Red Beers of West Flanders, where the less mineralized waters lead to the brewing of light and not very bitter beers There are four monastic Trappist breweries in the Ardennes, where the waters are highly enriched in calcium carbonate and as a result the typical brews are top-fermenting, dark brown, and sweet There is a fifth brewery at Westmalle, north of Antwerp, where the water is hard and a brew much closer to a bitter ale is produced Where the waters are poorly mineralized there are only two options First, there is the classical approach into pils brewing, typically around Louven, Alken, and Lindberg where the groundwater is derived mainly from superficials and surface run-off Second, there is a much more idiosyncratic Belgian approach, which is the production of Lambic, traditional in the Brussels area In this style wheat and malted-barley beers are produced using naturally occurring wild yeasts, which ferment completely and are very dry Hops are used not for flavour but purely to protect the beers from unwanted infection Fruit flavourings are often introduced, the best known being black cherry (Kriek) and strawberry (Framboise) Scandinavian brewing is dominated by lager-style beers, as would be expected from poorly mineralized waters derived mainly from Precambrian rocks, though occasionally a Belgian style approach is attempted, as with the juniper-flavoured beers of Finland Modern Brewing Many breweries are turning to the use of mains water that is deionized and then reconstituted to a given composition for a particular brew Commercially there are advantages in this procedure, specifically related to purity and continuity of supply Where a water grid system is in place a major disadvantage is that the composition of the water entering the brewery can change very rapidly as sources are changed, and this completely alters the nature of the brew in progress Wells and springs are still used by some breweries, but the problems of microbiological pollution, increasing nitrate content, and, near coasts, overpumping causing seawater intrusion are gradually reducing this number An interesting thought provided by one brewer is that, despite all that has been written about water type, the siting of breweries initially may have been controlled not by the analysis of the water but by the presence of a source of abundant water at a constant temperature in the days before thermometers were in constant use See Also Geology of Whisky Geology of Wine Minerals: Carbonates; Sulphates Palaeozoic: Carboniferous Sedimentary Rocks: Chalk; Limestones Further Reading Jackson M (2000) Great Beer Guide London: Dorling Kindersley