alex maltman talk

7/30/2019 Alex Maltman Talk

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Bla ckw ell Pub lish in g Lt d, Geology Today, Vol. 19, No. 1, JanuaryFebruary 200322

FEATURE

1. WineA conn ect ion betw een geology and w ine? Man y w ine

wr i t ings nur ture the idea at t ract ive, of course, to

geologists but sadly the real i ty is unclear. The few

at tempts to analyse exact ly how a connect ion might

operate have met a surprising lack of real data and

hav e tr i ggered v igorou s, som etimes passionat e, disa-

greements. At one extr eme of opin ion, n ot only does

geology underpin the success of vineyards but the

very t aste of the f inished w ine echoes th e bedrock.

Thus winetasters notes on f lavours are sprinkled

w i th w ords such as stony, ear thy and m ineral ic (yes,

and m ineral ly ) . One advocate of th is v iew can taste

volcanic ash in w ine f rom near Vesuv ius; anoth er n otonly detects the often-mentioned f l inty taste of the

whi te wine f rom Chabl is , an area under la in by ma-

r in e sedimentary rocks (Fig. 1) , but a lso a warm io-

dine fragrance that confirms that the sea definitely

covered Chablis a long t ime ago.

I t is a seductive m ental ju mp t o suppose th at some-

how f lavours are being commu nicated betw een bed-

rock and wine. Unfor tunately, no-one knows how

this can actual ly happen. Even the uptake of inor-

ganic ions f rom soi l in to v ine roots is poor ly under-

stood, let alone f lavourings that can persist into the

finished wi ne. So at the oth er extr eme, th e w hole idea

is dismissed as mere fancy. Providing the grape is

picked wh en r ipe, th is opposing argum ent w ould ru n,

then apart f rom the var iety of grape v i r tual ly a l l the

taste characteristics arise during the processes of

winemaking. In other words, wi th a g iven r ipe grape

var iety, the taste is determin ed in the w inery an d not

the v ineyard.

France is the heart land of a supposed relat ionship

betw een an areas w ines and local factors such as i ts

geology, and European law is increasingly enshr in in g

the idea. Thus champagne can only be made in the

Champagne area of France, so the argument goes,

because the par t icular mix of physical condi t ions

there encompassed by the much argued termterroi r cann ot be repl icated any w here else. Indeed,

the European Un ion is busy extending t he pr inc ip le to

a host of other agricultural products, such as cheese,

butter and blackcurrants. Opponents of the concept

suspect a Gall ic conspiracy designed simply to th w art

attempts to copy establ ished French products else-

w here. One pu blished art icle even refers to th e sup-

posed connection as terroir tr ickery; another talks of

v i t icul tural voodoo !

Som ewh ere betw een t hese polarized conv ict ion s

are views that, assuming the overal l cl imate is suit-

able, the condi t ions in w hich a v in e grows are l ikely

to inf luence the r ipening pat tern of the grapes, andhence the juice and the overal l nature of the f inished

wine body, mouth-feel, sugar-acidity balance, etc.

Therefore, geology, through the physiography of a

vineyard and i ts soi l , inf luences the performance of

the v ines and hence, indi rect ly , the character of the

wine, i f not the f lavour .

Physiography and soil

Different ial erosion of bedrock geology determ ines the

form of hi l lsides and val ley f loors across which vine-

yar ds spread, and hence th e meso-cl imat e of th e sites.

Just as other fru its, vines have to f low er, be pol l in ated

and set the f ru i t : a i r temperatures and wind condi -tions are critical at these stages. Frost has to be

avoided at a l l costs. Par t icular ly important is the

thermal belt along a hi l lslope, below the cold air

stat ioned over the hi l l top but above the cold layer

spread over th e val ley f loor. A lt i t ude affects the over-

al l a i r temperature, physiography inf luences

windflow, and the aspect of a hi l lslope i ts azimuth

and gradient inf luences the amou nt of radiant heat

received from the sun (Fig. 1) , a l l cru cia l dur ing f ru i t -

set and ripening.

Near-surface soi l has a major inf luence on vine

grow th as only th e deepest roots migh t reach bedrock.

FeatureWine, beer and w hisky: t he rol eof geologyAlex Mal tmanInst itut e of Geog raphy and Earth Sciences, University of W ales, Aberystw yth

Does geology aff ect the t astes of w ine, beer and

w hisky? And if so, how and by how much in each

case?


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Bla ckw ell Pub lish in g Lt d, Geology Today, Vol. 19, No. 1, JanuaryFebruary 2003 23

FEATURE

Fig. 1. Cross-section of t he Chablis district, France, show ing th e possible inf luence of geolo gy on vineyard physiograph y

and soils. At a, river erosion of relat ively soft l imeston es has led to a w ide valley pron e to spring f rosts, and co nsequent ly

few Chab lis vineyards. At b an d c, bedro ck of h arder m arly l imeston es, clayey marls and shell-beds (chief ly Exogyra

virgule) gives hi l lslop es, w ith a benef icial soil of colluvial clay and l imeston e clasts. The h il lslopes w ere shaped in

Quaternary periglacial condit ions: at b, facing NE, the slope has underg on e greater erosion an d is hence shallow er than at

c. I t yields goo d (so-called Premier Cru) w ines. At c, w hat of f ic ia ls deem t he best Chabl is wines (Grand Cru ) are produced

on a slope that faces SW and is steeper, th us receiving great er solar heat. (The inset sho w s how radiant h eat increases w ith

greater slope an d sunray-inciden ce angles. I is a radiat ion in tensity constant ). The colluvial cover reaches thicknesses up to

2 m and cont ains whi te ( l imestone) pebbles, enhancing i ts ref lect ivi ty. A cl i f f form ed in th e over lying l imestone helps

protect the slope f rom cold norther ly wind s. The plateau form of the hi l l top (d) fo l lows the hor izontal bedrock st rata and

hence receives less radiant h eat. The soil lacks colluvium an d is thin (< 0.3 m), consequen tly yielding w ines of only Petit

Chab lis off icial statu s.

Fig. 2.a Generalized cross-section of the hi l l of Corton,

Burgundy, show ing i ts much-ci ted correlat ion b etw een

w ine qual i ty and geology. Bedrock has been supposed to

play a role in th e aromas and f lavours of t he w ines , but

any demo nst rable l ink seems to b e throu gh soi l and

physiography, and hence meso-climate. In m ap view (b),

the vineyards are related not to th e outcrop pat tern of

bedrock ( fo l lowing topg raphic contours) but to soi l , s lope

posit ion and aspect. As at Chablis (Fig. 1), better w ines

come f rom the m id-slopes, here covered by col luvial

calcareou s soils (rendzines), wh ich are ref lect ive and w ell

drained. The most prest igious vineyards (Corton

Charemagne) l ie on t he w armer S and SW-facing slopes.

How ever, bedrock geology st i l l h as a role, as i t w i l l

contro l the nature of the soi l . In many famous v ine-

yards, th is is dist inct ly stony, qu i te unl ik e the norm al

v iew of agr icul tur al soi l . I ts chemist ry (e.g. N, K and

Ca content) af fects v ine growth, just as wi th anyother crop, a l thou gh w i th m anu r in g, fer t i l izat ion, etc.

this in most cases is now art i f icial ly managed. The

clay mineral content inf luences nutr ient retent ion

and the take-up of ions from the soi l , especial ly at

shal low depths. The mineralogy and c last content

determine the soi l s colour and albedo, and hence the

storage and r e-radiat ion of w arm th, especia l ly im por-

tant factors at night-t ime. Free drainage is al l impor-

tant and is pr imar i ly governed by soi l porosi ty and

permeabil i ty, together with slope angle. The usual i l -

lust rat ion of a l l th is is the Burgundy area of France

(e.g. Fig. 2) .

W hy , then, do some w inem akers dismiss such geo-

logical factors, or at best deem them tr ivial? In gen-

eral, the most fervent opposing voices are from theNew Wor ld of winemaking, newly successful wine-

producing areas such as New Zealand, Austral ia and


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FEATURE

California. Part of the reason for the dichotomy of

v iews must l ie in the very suddenness wi th which

such areas have ascended to fame; there has simply

been insuff icient t im e to test th e ideas. Mor eover, N ew

W orld w inemakin g has been character ized by a m orescient i f ic , technological approach ( f rom which the

Old Wor ld is now learning much), and unt i l recent ly

such efforts have been directed more toward

winemaking procedures than ef for ts in the v ineyard.

Many such winer ies are large, grow several grape

var iet ies and m ake a w hole range of win es in some

cases including the products of Bordeaux, the Rhone,

Chiant i and the Rhine val ley coming f rom a s ingle

distr ict! Inf luences of part icular factors are therefore

bound to be blurred and wi l l need t ime to evaluate.

Mor eover, some of th e greatest N ew W or ld w ines are

actual ly ski l ful blends, of no closely identi f iable prov-

enance. These are al l general izations. There are nu-merous exam ples in th e New W or ld w here some geo-

logical inf luence seems clear, and i t may be

signi f icant th at th ey tend t o be in th e more evolved

distr icts, often special ising in a part icular style of

wine. Wel l -known examples inc lude the Coonawarra

distr ict of Austral ia, the Niagara Peninsula, Canada,

and th e Diamon d Creek and Rut her ford Bench areas

of Napa Valley, Cali fornia.

Other explanations for the l ink being rejected con-

cern the geology i tself . First, i t has to be said that

discussions in the popular l i terature are replete with

geological misunderstandings and mistakes that can

hardly help in c lar i fy ing th ings. Second, i t so h appens

tha t m any m a jor N ew W or ld w in e-produc ing d ist r i c t s

are s i ted on wide, f la t val ley f loors rather than hi l l -sides. Such areas are underlain by thick, mixed al lu-

vial deposits with complex soi ls, and hence minimal

inf luence from the bedrock substrate. The Central

Val ley of Cal i forn ia, for example, inc luding the v in e-

yards of the University of Cali fornia at Davis where

much modern v i t icul tural research has been carr ied

out , h as topsoi l over 70 m deep. Moreover, such areas

tend to be heavi ly i r r igated and chemical ly t reated,

w i th kn ow n drainage var iat ions simply being al low ed

for in the water ing programme. Thi rd, many antago-

ni sts voices are raised from w ineries th at are un der-

lain by a complex, intr icate geology. I f there is some

conn ection betw een bedrock an d grapes, i t is going t obe far simpler to demonstrate in a sett ing such as the

even, gent ly d ipping st rata of Burgun dy (Fig. 2) th an

th e col lage of fault -boun ded sl ivers that dom in ates th e

plate-boundary set t in g of m any of the Cal i fornia v in e-

grow ing regions (Fig. 3) .

Other geologi cal influences

Man y consumers have come to bel ieve that a l l w ines

(and beers, for that matter) have not only to be clear

Fig. 3. Schematic cross-

sect ion, show ing the

geology of Sonom a County,

Californ ia, (based on a

draw ing by Terry Wright ) .

He has noted som e

correspond ence betw een

soil chem istry and vine

growth but , in cont rast

w i th the Chabl is and

Burgun dy exam ples (Figs 1and 2 ), most w iner ies are

und erlain by an int r icate

geology and each produ ces

a range o f red and wh i te

w ines, thus blurr ing any

geology-w ine l inks. Of f ic ia l

vit icultural areas are nam ed

in ital ics; the boundaries

relate l i t t le to t he

underlying geology.


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FEATURE

but m ust be br i l l iant . Most w ine and beer should fa l l

clear natural ly, but many processors choose to f i l ter

and f ine their products, despite the r isk of removing

flavour components. Geological materials are widely

used. Fi l tering commonly no longer involves asbestosbut uses powdered diatomite, often referred to in the

trade as kieselguhr , capital izin g on i ts high permeabil-

i ty an d th e inertn ess of the f ine grain s of si l ica. Im por-

tant sources are the Palaeogene lake deposits in NW

Denmark and N Germany, and the upper Miocene

Lower Pl iocene mar ine Monterey Format ion around

Lompoc, Cal i forn ia. Fin ing can involve centr i fuging

and/ or chi l l in g, but comm only u ses the sw ell ing c lay

mater ia l kn ow n as benton i te. Slur r ies of benton i te are

suspended in the wine or beer to absorb the haze-

forming compounds, before the part icles sett le out

natural ly . The most important sources of bentoni te

are around th e Black Hi l ls of W South Dakota and EW yomin g, USA . Here, volcanic ash layers in th e Cre-

taceous Mowry and Bel le Fourche shale format ions

have been al tered and hydrated, mainly to

montmor i l loni te. Inc idental ly , s tatements on bot t les

of wine or beer that the contents are suitable for

vegetar ians are s imply imply ing that any c lar i f ica-

t ion employed such in organic agents rather th an th e

al ternat ives which are of animal or ig in.

Final ly, i f geology is defined to include extrater-

restr i al bodies, i t has to be m ention ed that an incr eas-

ing number of farmers, and especial ly grape growers,

are p lann ing th ei r tasks according to lu nar and plan-

etary ph ases. Despite i ts my stic, New A ge rin g, suchbiodyn am ic m ethods are passionat ely defended, and

there is some support ing scienti f ic evidence. I t is the

case that some farmers, whose very l ivel ihoods de-

pend on th e success of th eir crops, are convin ced th at

improved harvests resul t f rom thei r tak ing the extra

t im e and expense to w ork accordin g to these extrat er-

restr ial inf luences.

2. Beer

The inf luence of geology on beer is much less subtle

than on wine. This dif ference comes about because,

w hereas win e is a lmost ent i r ely th e product of grape

jui ce, beer consists predomin ant ly of w ater , and th is

in most cases has been drawn di rect ly f rom the

ground. The geology of the aquifer directly affects the

chemist ry of the brewing water and th is demonstra-

bly inf luences the brewing process and the character an d, y es, th e tast e of th e fi n ish ed beer . H istor i -

cal ly, brew ers learned em pirical ly of sui table wat ers,

but today the interplay between hydrochemist ry and

brewing is the subject of a vast technical l i terature.

Water in brewing

Th e thr ee cent ral steps in br ewin g are the steeping of

mal ted bar ley an d other cereals in hot w ater in order

to ext ract organic compounds a stage known as

mashing boi l ing the resul t in g l iquid w i th h ops, and

ferment ing wi th yeast . The chemist ry of the water

inf luences al l three stages, but especial ly the mash-

ing. Here, where pale ( i .e. unroasted) malted grainsare used, their r ich cocktai l of proteins, starches and

complex sugar s is conv erted by enzymes into simpler,

fermentable forms. The actual reactions are chief ly

govern ed by th e temperatur e and acid ity (pH) of th e

mixture. Temperature is, of course, easi ly control led,

but th e acid i ty is a more chal lenging mat t er . Natu ral

brewin g w ater tends to be neutr a l or sl ight ly a lkal in e

(pH > 7), owin g to the presence of ions such as Ca,

Mg, HCO3

and CO3. How ever, speedy, eff icient m ash-

ing n eeds a pH of arou nd 5 5.5, so adjustments to the

acidity ar e needed not a straigh tforw ard prospect

wi th a l l the var ious ions involved. To the rescue,

how ever, come roasted mal ts, w hich contain, amon gother th ings, natural phosphates that help neutra l ise

the effect of high HCO3

concentrations. The effect is

greater with higher degrees of roast; amber malt re-

duces pH less than chocolate malt. Highly roasted,

black malt shif ts acidity most. Therefore, introducing

roasted m alts as appropr iate can in crease acidity int o

the desirable range. At the upper l imit of the pH

range, the mashing wi l l leave unfermentable prod-

ucts, leading to a grainier taste, accentuated by the

fact that normal ly fewer hops can be used in such

water .

These days, techn ology and h ydrochemical kn ow l-

edge al low brewers to a l ter the water chemist ry asrequi red, but h istor ical ly , hard w aters w ere un desi r -

able for brewing. They were s imply too alkal ine for

eff icient mashing and the CO3

content inhib i ted en-

zyme act iv i ty . At tempts at chemical adjustments in-

troduced off-f lavours. On the other hand, soft waters

m ashed w ell , and i f they cont ained sign if icant SO4

t h e

beer acquired an unrival led taste and bite, together

wi th a stabi l i ty such that i t could wi thstand being

transported.

Breweries and beer styles

The groun dw ater at Bur ton -on-Trent is often deemed

Table 1. Representat ive ionic con centrat io ns (averaged f rom several l i terature sources), in

parts per mi ll ion, of brew ing w aters ment ion ed in the text .

Bu rt o n Ed in b u rg h Pilzen Fo rt Co llin s M un ich Du b lin Lo n d o n

Ca 282 110 7 13 75 80 90

M g 4 3 24 2 2 18 19 4

Na 28 35 2 2 6 1 24

SO4

720 110 5 5 10 5 5

Cl 37 45 5 5 2 1 1

CO3

1 7 1 1 7 0 1 2 1 4 1 5 2 1 6 4 1 5 6


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FEATURE

to be an ideal brewing water as i t has a natural ly

balanced blend of beneficial ion s th at giv es an acidity

perfect for brew ing pale ales (Table 1). W hil e th e Ca

content is very h igh , i t is largely r elated to an u nu su-

al ly h igh SO4

content so desirable in pale ales

ra ther than CO3 . The gypsum in the under ly ingevapor i t ic bedrock (Fig. 4) is the key. In fact , w el ls

penetrating the Triassic sandstones encounter SO4

levels as h igh as 90 0 p.p.m. A s brewin g became in-

creasingly centr a l ized dur ing Victor ian t im es, and th e

Br i t ish Empire grew, i t t r anspi red that th is unu sual ly

high SO4

content i n beers from Bur ton gav e a stabi l i t y

which al lowed the beer to be exported, and shipped

even as far as India. H ence the styles know n as export

ales and India pale ales were born in Burton (and

later developed in Edinburgh , w hich also enjoys high

SO4

waters). The high SO4

content also contributes a

sl ight sulphury nose, which to some dr inkers has

been th e desirable hal lm ark of Bur ton beers (alth oughto others i ts memorable characterist ic is the Epsom

salts laxati ve effect!). A compar able situ ation exists at

Tadcaster, Yorkshire, but based on the very hard but

sulph ate-r ich w aters f rom th e under ly ing M agnesian

Limestone. I t is no accident that th is smal l country

town boasts three major breweries.

Beer making changed dramat ical ly in the mid-

19 th cen tury , w i th improvements in ma l t i ng tech-

niqu es and br ewin g technology. Pale mal ts could be

more ef f ic ient ly mashed and, wi th the advent of re-

fr igeration, i t became possible to ferment and store

the brew at low temperatu res in order to enhan ce i ts

clean taste. Thu s lager w as born . Brewers at Pi lsen,Czech Republ ic , foun d th at th ei r low -min eral -content

w ater w as ideal ly sui ted to this del icate new style. The

soft w ater also al low ed the bold use of dist in ct ive aro-

mat ic hops: the product became known as pi ls , or

pi lsener. The beer became an inspirat ion to pretend-

ers the world over. Pi lsen is located part ly on

Stephanian (Upper Carboniferous) sandstones and

part ly on Upper Proterozoic m etamor phic r ocks from

which the water was drawn. These pel i tes and

psammites are intr insical ly impermeable, but suff i-

ciently f issur ed to give som e storage capacity w ith

min imal in teract ion between the aqui fer and the wa-

ter . Consequent ly , the water has only a l i t t le hard-

ness, which tends to be offset anyway by a modicum

of CaSO4. Other ion s that can bedevi l brew ing w aters,

such as K an d Cl, are sparse. The w ater at Budw ar,

15 0 km t o the SE and hom e of the or ig inal Budw eiser

brew ery, w as even softer , f rom a 30 0 m deep ar tesianw ell in fr actu red, older Pr oterozoic gn eisses and

migmat i tes. Amer ican brews boast ing Rocky Moun-

ta in water sources have s imi lar ly low ionic values

a l though w i th 13 p .p .m . Ca and 14 p.p .m . CO3, a l i t-

t le mor e hardn ess and th ese, too, hav e prompt ed the

production of l ight, clean tasting beers.

Both th e heavi ly m ineral ized and f lavour fu l w aters

of Bur ton and th e relat ively pure and del icate w aters

of places l ike Pi lsen have hardness and alkal inity in a

natural balance that a l lows ef f ic ient mashing wi th

pale malts. Consider, how ever, th ose brew ing centr es

wi th waters lacking such balance. For example, Mu-

nich does not, str ict ly speaking, have good brewing

w ater (Table 1) . M oreover, a celebrated German law

forbids chemical addi t ions to brewing water (a l -

though boi l ing would be permi t ted and would reduce

the elevated temporary HCO3

hardness); so pale-beer

product ion, h istor ical ly , had to involve re lat ively inef-

f icient mashing. Brewing dark beers, however, is a

di f ferent mat ter , wi th the roasted mal ts able to in-

crease acidity in to an acceptable range. M un ich brew -

eries chief ly drew their water from the Pleistocene

f luv iat i le and glacio- fluv ia l sands and gravels wh ich,

derivin g from th e nearby calcar eous rocks of th e A lps,

give a high CO3

content and high alkal in i ty . This is

why Munich became best known for i ts dark beers.

Even the paler lagers produced today have a r icher

taste than, say, pi lseners, part ly because of the

un ferm ented compoun ds indu ced by t he re lat ively a l -

kal ine water .

Perhaps the extrem e case of using h eavi ly r oasted,

high-phosphate malts to reduce the pH levels of

mashing water to acceptable levels is in Dublin. The

city is located on Mi ddle Carbon iferou s Lim eston e and

i ts water is h igh in CO3, as h igh as at Bur t on-on-Trent

but much weaker in Ca. Thus the water is hard and

alkal ine, g iv ing a d ist inct ive mouth- feel , and wi th a

lot of buffering capacity. However, the use of very

Fig. 4. Schematic geological

cross-section of the Burton-

on-Trent district, England.

Brew eries obtain w ater

f rom both bedrock and

surf icial deposits, but bothare gypsiferous and rich in

SO4

and ot her ions.


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FEATURE

dark roasted malts lowers the mash pH adequately,

and this has led to the famed black stouts of Dublin.

The mashing is st i l l relat ively ineff icient, but the

unconverted, non- fermentable mater ia l g ives a

grainy, nutr ient- r ich beer af ter a l l , Guinness didonce promote the not ion that i ts product is good for

you .

A comm on t a le is that Guinn ess brewed at i ts Lon-

don brewery is infer ior , through crucia l ly lacking

water f rom the River L i f fey, on which the Dubl in

brew ery stands. Yet th e operati ons in both places use

hard, l im estone-der ived w ater . (Actual ly , t he Dubl in

brewing water is not taken f rom the Li f fey but f rom

the Grand Canal , which has several inputs, a l l of

which der ive f rom Lower Carboni ferous Limestone.

The chief source is at the ecological ly important

Pollardstow n Fen, near N ewbr idge, Co. Ki ldar e, fed by

over 40 spr ings in the l imestone.) The story may,however, contain some t ruth. The London water is

drawn f rom the Chalk, and hence has di f ferent con-

tents of Mg, Cl, etc., which are l ikely to inf luence the

f lavour prof i le . In addi t ion, the greater am oun ts of Na

and K at London w ould be expected to enh ance per-

ceived sweetness. In fact, i t is th is alkal in e chemistry

of London groundwater that gave r ise to the sweet

por ters and stouts ( involv in g pH-reducing dark mal ts)

h istor ical ly associated w i th that c i ty .

Other geological i nfluences

Besides w ater, the tw o prim ary con sti tuent s of beer

are cereals and f lavou rin gs from h ops. In a w ay, geol-ogy h as som e inf luence on both . A v ariety of cereals is

used in beer making these days, but most highly re-

garded beers are centred on barley. A reas sui table for

bar ley growing are very largely d ictated by overal l

cl imatic and agro-economic factors, but geological

condit ions can affect growth in detai l . For example,

bar ley grow ing on soi ls over ly ing Gaul t Clay per form s

differently from that on Lower Greensand soi ls. Much

mor e expl ic i t ly , hop-grow ers, rath er l ike w inemakers,

tend to advert ise th at soi l enh ances th e arom a of their

par t icular hops the m ineral ly character of Kent

Fuggles, for exam ple. How ever, i t seems clear t hat

the role of geology here is in enabling the develop-men t of deep, free-drain ing soi ls, wi th som e access to

w ater . Water retent ion at depth is par t icular ly useful

dur ing the dr ier t imes of summer as the water is

mainly taken up dur ing the second hal f of the grow-

ing per iod, after f lower ing an d dur ing development of

the arom at ic hop con es.

Such condit ions are prov ided by th e deep, strat i f ied

soi ls overlying the thick Tert iary molasses of the

W olznach, Hal ler tau, region of Germ any. In fact , the

proximi ty of th is ideal hop-growing area to Munich

may have been the tr igger for establ ishing the city as

a brewin g centr e, hops being aw kw ard to convey over

long distances. Moreover, modern machinery can

w ork t he f lat , fer t i le hopf ields at Hal ler tau, w hich has

now become pre-emin ent outs ide the USA . Over 7 0%

of Am er ican h ops are now grow n on the deep al luv ia l

soi ls of the Yak ima and W i l l iamet te Val leys of W ash-ington and Oregon. These are volcanic in nature, de-

r iv ing f rom the nearby Cascade volcanic uplands.

Clay layers occur at depth i n some places, but th e soi ls

are loose and very free-draining, such that sophist i-

cated i r r igat ion systems are now used. The th i r d im -

portant area in the USA is Treasure Valley, near

Boise, Idaho, which provides hops for Anheuser-

Busch, the wor ld s largest brewery concern. This

area, too, has th ick fert i le volcan ic soi ls, here derived

from the basalts of the Snake River volcanic plateau.

Hop grow ing in the Br i t ish I sles long ago w i thdr ew

to SE Engl and an d th e SW M idlan ds, largely for a

variety of socio-economic and infrastructure reasons.How ever, deep and suitably w ell-drained soi ls occur

in both regions for example, in Kent where Gaul t

Clay is over la in by r iver gravels and loams. In the

Frome and Teme river val leys of the Ledbury

Bromyard dist r ic t , soi ls der ived f rom the under ly ing

Lower Old Red Sandstone are moist, while providing

suf f ic ient depth and drain age. A s wi th w ine, bedrock

geology in f luences the physiography of th e land and

hence the meso-cl imate and th e al l- importan t arom a

prof i le of the r ipe hops. In a humid country l ike the

UK, areas w ith st i l l , dam p air h ave to be avoided be-

cause hops are very prone to m i ldew , one reason w hy

SE England has remained re lat ively important . TheSW Midlan ds, ly ing in the ra in shadow of the Welsh

Hil ls, also has suff iciently dry, draughty air.

3. Whisky

Many a geologist enjoys a glass of malt, not least by

knowing that geology has inf luenced i ts character

th rough the w ater th a t i s a l l -impor tan t to w h isky . A t

least , th at s wh at th e market ing te l ls us. For in con-

t rast wi th i ts unsung ro le in beer , the importance of

w ater is grandly t r um peted in m any an adver t isement

for whisky. And why not? Water is involved at a l l

stages of whisky production; even after dist i l l ing andageing, th e fin ished spi r i t is typical ly 60 % w ater . An d

although, just l ike beer, whisky is essential ly made

from malted cereals fermented in water, hops are

rarely involved, so the taste-role of water might be

expected to be promoted even more. Closer scrutiny,

how ever, suggests that w hi le crysta l waters tumbl in g

from gran i te moun tains make good adver t is ing copy,

they are actual ly of l i t t le signif icance to the taste of

whisky. Moreover, the role of geology is lessened be-

cause m any dist i l lery w ater sour ces are sur f icial,

ra ther than draw n d i rect l y f rom an un derground aq-

ui fer . Certa in ly a good supply of w ater is param oun t


7/8


FEATURE

in dist i l l ing operati ons, but factors such as the cereals

used, the use of peat smoke dur in g th e mal t in g ( in the

case of Scotch w hi sky ), the way th e dist i l lat ion i s con-

ducted, and th e matur at ion pr act ice, a l l seem to h ave

a far greater inf lu ence on t he taste profi le of a w hiskyth an does the w ater th at is used. Sadly, th e role of

geology and w ater in al l th is seem s to be mu ch less

than market ing would have us bel ieve.

Water in whisky

The bulk of the wor ld s whisky is manufactured in

large plants, many of w hich produce a range of sty les

in the one factory. The enormous operations in Japan

and Canada are examples, together wi th the two

major dist i l lery complexes in Ireland. The chemistry

of the water supply is adjusted in these plants as

needed; i ts actual m ake-up is probably n egligible any -

way. Thus, a l though several countr ies produce vastamounts of these kinds of whisky superbly suited to

th eir pur pose in t he present cont ext th e focus has to

be on Scotland and the Eastern USA, and the hand-

made, characterful single products of small dist i l ler-

ies, man y of lon g pedigree. I t is back in th eir histories

that we f ind the reasons for the locations of these

dist i l ler ies, and wi thout quest ion water supply was

crucia l .

Take, for example, the Scott ish Highlands. The

important thing was a consistent, rel iable source

f lowin g al l sum mer, not f rozen in w inter of consist -

ent ly dr in kable, and h ence usable, w ater (= pure in

advert ising speak). Taxation of Scotch whisky drovei l l ici t production to secret locations, and the l icensing

of d ist i l ler ies in th e 182 3 Excise Act a l low ed only th e

best dist i l ler ies ult imately to survive only those

w hich, am ong everyt h in g else, had a good w ater sup-

ply. In many cases, the water happened to be sl ightly

acid, and sof t . Now the n ot ion h as developed that th e

water mustbe soft for qual i ty dist i l l ing. In deed, adver-

t isemen ts for several Scott ish dist i l ler ies proclaim th e

vir tu es of the softness of their w ater supply . The in-

volvement of granite is also often lauded, although in

fact most dist i l ler ies in Scotlan d are sited aw ay from

granite. The water for many renowned Speyside dis-

t i l ler ies, for example, f lows over, and to some extentthrough, quar tz i te and a whole range of other meta-

mor phic rocks, a l thou gh i t is st i l l t ru e that th e resul t -

ing waters are soft. But is this softness important?

Some Speyside w hi skies w ith th e characterist ic taste

profi le of the distr ict involve water affected by calcar-

eous rocks such as Dalradian l imestones, and some

dist i l ler ies in NE Scotland and Orkney use signif i-

cant ly hard water , drawn f rom calcareous Old Red

Sandstone. Indeed, one very wel l known and ac-

claimed dist i l lery in the north-east vaunts the excep-

t ional ly hardnature of i ts water .

The inconsistency is underl ined by dist i l ler ies in

Kentucky and Tennessee, where the US industry is

concentr ated. The region h as close historical paral lels

wi th Scot land, and where a good water supply has

been equally crucial for successful dist i l l ing, but

where the water happens to be high in HCO3

and al -

kal ine. Almost al l the dist i l ler ies are sited onOrdovician l im eston es, yielding w aters of pH as hi gh

as 7.58. And their advert ising celebrates the result-

ing hardness!

A question arises, recal l ing th e brewin g process, of

how ef fect ive mashing can be at ta ined wi th these

hard waters, as roasted, dark, grains are tradit ional ly

not used in whisky product ion. The answer l ies

largely in the kinds of cereals employed. A mix of

grain s dif ferent from Scotland is typical (ref lect in g the

di f ferent growing condi t ions in the USA) and these

provide micro-organisms capable of reducing the pH

of the mash to suitable levels. For example, lactoba-

ci l l i in the grains soon yield suff icient lact ic acid toreduce th e pH v alue, especial ly as these wat ers do not

tend to be well buffered. Moreover, port ions of the

grain are used a second t ime the so-cal led sour-

m ash t echn iqu e in or der to consolidate th e effect. In

fact , Amer ican dist i l lers argue that the high pH of

thei r w aters is benef icia l , wi th the Ca and M g content

(and low Fe) enhancing yeast metabol ism, and

prompt ing undesi rable t ransi t ion metals to form hy-

droxides and precipitate out. Much US advert ising

praises the iron-free water ( in contrast to some

Scotch w r i t in gs w hich suggest th at i ron f rom the peat

is beneficial). Thus American whiskeys are made

from different gr ain s from Scotch an d hence, togetherwi th d i f ferent d ist i l l ing and, especia l ly , maturat ion

practices, the product dif fers greatly in taste. In both

cases, any direct f lavou rin g role of w ater is left at best

very in di rect .

But w hat about the w ater that is added af ter d ist i l -

la t ion, to d i lute the spi r i t for cask matur ing and f i -

nal ly for bott l in g? Obviously local w ater is used, so

migh t n ot th is di rect ly inf luence the f inal taste? No

because almost al l dist i l ler ies, both in Scotland and

the USA, careful ly de-ionize their water at these

stages, to avoid any disagreeable chemical reactions

occurr ing. The fact is that i f the taste of whisky is

signif icantly affected at al l by water, i t arises i f theconsumer adds his own water to his sipping glass!

Other geologi cal influences

Th e great dist inct i veness of Scotch w hisky i s i ts

peatiness, present to v ariou s degrees in dif ferent prod-

uct s. Th is deriv es largely from th e peat smok e used in

the mal t ing process ( rather than the of ten-c i ted

peatiness of the water), and geology can have some

influence on the avai labi l i ty of peat. Consider the Isle

of Islay, for example. I t is no coincidence that this

home of the most heavi ly peated whiskies of al l has

exceptional ly thick deposits of peat, which can there-

fore be lavishly employed. The peat has accumulated


8/8


FEATURE

in exten sive, f lat, low-ly ing t racts, developed on an

unusual ly sof t bedrock for th is par t of the wor ld:

Dal radian pel i tes adjacent to a regional ly important

faul t zone (Fig. 5) .I t is cur ious that of over 22 dist i l ler ies that once

operated on Islay, over half were clustered along one

coast of this irregular island. Three of them remain

today th e archetypal Islay w hiskies (Fig. 5) . Certa in ly

the nearby peat-covered Dalradian quartzites endow

suit able dist i l l in g w aters, but perhaps some reasons

for this concentration are historical and geological.

In the days of i l legal dist i l l ing in Scotland, a topogra-

phy th at al low ed hidden sites and easy getaw ays mu st

have been an advantage. How ideal must the con-

spicuou s dif ferent ial w eatherin g of th e SE coast of Is-

lay h ave been in th ese respects, wit h resistant

metabasite sheets in tru ded into relat iv ely soft pel i tes,g iv ing a mul t i tude of sharp r idges hid ing t iny g lens,

and a maze of offshore reefs and islets that conceded

safe navigat ion only to th ose wi t h local know ledge.

In the USA, the l imestones that yield the precious

dist i l l i ng w aters also give r i se to cave systems, prov id-

ing ideal condi t ions for whiskey maturat ion. For ex-

ample, the only whiskey dist i l lery west of the Missis-

sippi st i l l operates on i ts original si te, located on

rel iable Ca-rich springs, and i t continues to age i ts

products in caves developed in Carboniferous Lime-

ston e. Some l im eston es of Centr al Kent uck y an d Ten-

nessee contain apati te f i l l ings and phosphorite nod-

ules that lead to soi ls unusual ly r ich in phosphate

(2.4% and more). Not only does such very fert i le soi l

favour the growth of corn, the cereal most widely

used by the dist i l ler ies, but also of the indigenous

white oaks that are preferred for cask-ageing thewhiskey.

Conclusions

In sum mar y, geology h as var ious ro les in th ese three

celebrated dr ink s. In w inemakin g, al thou gh th e inf lu-

ence of geology is much vaun ted in cer ta in qu ar ters,

i t is h otly disput ed in ot hers. The role does seem to be

indi rect , throu gh v ineyard phy siography an d soi l ; be-

yond that the jury is st i l l out . The connect ion, h is-

torical ly at least, between geology and the character

of beer is much c loser , through groundwater

hydrochemist ry, but great ly unsung. The ro le of wa-ter in the taste of wh isky is, notw i thstanding evoca-

t ive adver t is ing blurb, e lusive. W hen you next pour a

glass of your favour i te mal t w hisky, th in k careful ly i f

you are adding w ater. Unl ess i t is de-ioni sed, i t is at

that stage that geology m ight be having i t s most d i -

rect af fect on w hat you taste!

Suggestions for further reading

W ilson, J.E., 19 98 . Terroir:The Role of Geology, Cli mat e

and Cultu re in the M aking of Fr ench W ines. M i tchel l

Beazley, London, 336pp. This handsome book

beaut i fu l ly por t rays mu ch detai l on th e geology ofthe classic French wine distr icts, but evades how

the wine is affected, a shortcoming expounded in

Hancock, J., 1999. Feature review, Journal of W ine

Research, v .10 , pp .4349 .

Lloyd, J.W., 1 98 6. H ydrogeology an d beer, Pr oceed-

ings of the Geologists Association, v .97 , pp .213

219. Unusual ly , th is ar t ic le expla ins the l ink be-

tw een geology and somebrewing waters.

Cribb, S. & Cribb, J. 19 98 . W hisky on the Rocks, British

Geological Survey, 73pp. Uses the locations of

whisky dist i l ler ies to int roduce very s imply the

geology of Scotland, although the nature of the

link is little discussed.

Fig. 5. Simplif ied geological

map of SE Islay, Scotland.

Not al l the r idge-forming

met abasite sheets areshow n, and none that is

w hol ly below the sea.

Dist i l leries are nam ed.

Volcanism of a sort

For the not so subt ly named Etna is a woman

operating under r igorous and agonising self-dis-

cipl in e. Volcan ic passion s exist beneath h er sub-

m issive faade. Like Haw th orn es nov el The Scar-

let Letter, this is a story of passion within a

f ramework of rest ra int . Joanne Harr is , in a

review of Ani ta Shreves new novel Al l H e Ever

W antedin W aterstones B ooks Quarterly .

alex maltman talk

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