Geology and Beer

It was Dave Schumaker’s post over at Geology News on the use of Eocene yeast extracted from the gut of a weevil trapped in amber to make beer that has inspired my to write a post on the two subjects closest to my heart (well, at least my liver) – geology and beer.

Students of the study of fluid inclusions in amorphous silica (or zymurgists) will know that there is a strong link between the style of beer and the geology of where it is brewed. Bitter (or pale ale) is associated with the town of Burton-on-Trent in Staffordshire, UK, porter with London, stout with Dublin and lager with Pilsen (now Plzen) in the Czech Republic and the association is down to the geology.

Burton-on-Trent has been associated with brewing since the 6th Century, with beer making by the Monks at Burton Abbey, but became particularly noted in the 1800s because the pale ale brewed there had a superior hoppy taste to those brewed elsewhere. This was due to the water for the ale being drawn from wells penetrating the gypsum (calcium sulphate) bearing Permo-Triassic strata beneath the town. The resulting ‘hard’ water, rich in suphate, yields a clearer, brighter, bitter with a more hoppy flavour. The presence of sulphate ions also cause a particular sulphurous aroma, known as the “Burton Snatch”. Brewers of pale ales elsewhere now add calcium sulphate during the brewing to imitate the natural Burton waters, a process known as “Burtonisation” of beer. The natural calcium rich water also helped in the preservation of the beer, the drop in pH inhibiting microbiological infection and allowing it to be transported further without spoiling, even as far as India, hence the term India Pale Ale (or I.P.A.).

Dark ale or porter was first produced in London in the 18th century. London is situated on Cenozoic sands and clays but most water is extracted from artesian wells from the underlying Upper Cretaceous Chalk. The resulting water was consequently high in calcium and carbonate but low in sulphate, again giving a characteristic taste (porters and stouts do not undergo Burtonisation).

In 1759, Arthur Guinness in Dublin pioneered a denser (or stouter) porter, later to be known as stout. Dublin is located on Carboniferous Limestone, giving a similar high calcium, carbonate, low sulphate water to the London water used for porters but there is a significance difference in the trace element chemistry. Up until 2005, Guinness was brewed in both London and Dublin and it was noticeable that the two tasted slightly differently, Guinness tasting nicer in Ireland than it did in the UK, despite being brewed to exactly the same recipe. The only difference was the water chemistry, the London chalk having slightly different proportions of sodium, potassium, magnesium and chlorine to the Dublin limestone resulting in a sweeter taste. It is now all Dublin brewed.

Pilsner Lager is also the consequence of its unique water chemistry. The water at Plzen in the Czech Republic is ‘soft’ being poor in disolved material derived from the Late Palaeozoic rocks. This ion-poor water results in a light, clean-tasting hoppy, pale lager. The word ‘lager’ means means storage, and it was the cold storage in local caves that gives rise to the lagerisation of the beer.

So next time you are enjoying a beer just think of the geology involved. Cheers!

Bitter Porter Lager
Calcium 170 100 50
Magnesium 15 10 2
Bicarbonate 25 100 25
Chloride 200 300 10
Sulphate 400 100 10

Typical Trace Element Concentrations (ppm) Source: Murphy & Son Limited