McLAREN VALE GEOLOGY MAKES FLAVOUR

RHONE EXPERT JOHN LIVINGSTONE-LEARMONTH ENJOYING A GLASS OF GRENACHE ON A BONNIE SPRING DAY IN McLAREN VALE ... photograph by KATE ELMES - INDEPENDENT WEEKLY

Rhone Man Tastes Vales Stones
500 Million Years Missing
Some Hammy Ironstone Survives

by PHILIP WHITE ... a version of this first appeared in THE INDEPENDENT WEEKLY

John Livingstone-Learmonth is a student of the Rhone. He has crossed its countryside, kicked its dirt, contemplating its geology, and studied its wines for thirty-five years. He knows three generations of growers, and has watched their attitudes and vineyard husbandry change. Or not change. He is the living library of Rhone whites, cellaring, and knowing implicitly decades of viognier, roussane and marsanne. He was in Condrieu, the home of viognier, when its total plantings had dwindled to around twelve hectares. He has written scholarly books about this; now he is attempting to encourage those Rhonely types to learn more about their geology.

“Take Saint Joseph, in the Rhone”, he said, over a breakfast tasting. “It is transversed by streams which come down from the range to the west. When I taste those wines, and study their prices through history, these vary in parallel to my opinions of their quality, depending on the various alluviums they have washed downstream ... the geology of these sources are vital sources of flavour. The old growers accepted all this for centuries, without knowing why; without appreciation of precisely why and how geology influences the flavour and structure of their wines.”

“We need an international guest at our wine show” Vales PR flak Elizabeth Tasker had said, half apologetically, “to give it weight in the publicity ... we need a point of difference to elevate our image.” Which is why John was here. But we were discussing something bigger than PR.

Way beneath the Willunga Basin lie the rocks of the Neoproterozoic, stuff that was there around a billion years ago. Before multi-cellular life really took off. A billion years before humans invented God. Atop those lie layer upon layer of deposits left by repeated intrusions and retreats of the ocean, which has all occurred during the ice ages of the last sixty million years. Only in that time have we drifted away from Gondwanaland, the great Antarctic continent. That may seem a long time back, until you think of the preceding billion years or so.

When Earth’s water concentrates, frozen, at the poles, the sea falls. Eighteen thousand years ago the beach was away off on the edge of the continental shelf, at least one hundred kilometres from where it now stands. Ten thousand years ago, you could walk to Kangaroo Island. There were aboriginal people living where the Bass Straight now flows.

I attempted to explain the differences between the geology of McLaren Vale and that of the Rhone, the target and source of John’s life’s fascination, when a weird reality hit me with newfound clarity. Apart from their newer stuff, which was laid down or exposed in the same last sixty millions that saw the top layers of the Willunga Basin form, the basement Rhone is from the Jurassic, the age of dinosaurs and coniferous forests, from 135 million to 180 million years ago.

I found myself having to explain that those layers of history do not exist in McLaren Vale. They are quite simply gone. Away. I can show you sites in the Vales where you have a layer of Neoproterozoic rock topped with layers of stuff that are sixty million years old, from the Eocene. Five hundred million years of geology have vanished. The stuff that once filled that gap is the geology on which the Rhone Valley grew. So we had an exciting point of difference: the bit missing from the Vales is the bit in which France happened.

Regular readers will know of my obsession with licking rocks and dirt to taste their flavour. In spite of some nonsense circulating about some boozy US geologists claiming the opposite, grapes are little bags of sugary water, which are directly influenced by these flavours of the Earth.

Soil, the obsession of Australian winemakers, is the dandruff of the Earth to the geologist. Drive through any cutting on any of the roadways in our Hills or the Vales, and look at the soil: it’s usually only a metre deep, if that. The key roots of vines drive quickly through that dandruff, and derive flavours from the skull bone beneath. John Livingston-Learmonth understands this more than any wine writer I have met. I passed him a small lump of ironstone from the Yangarra sands. It tasted like a slice of smoky Iberian ham.

UNIRRIGATED 1946 MODEL BUSH VINE GRENACHE IN AEOLIAN SEMAPHORE SAND AT YANGARRA ESTATE NEAR KANGARILLA

A team of master geologists, W. A. “Bill” Fairburn, Jeff Olliver, and Wolfgang Preiss, all colleagues of mine from the old days of the Mines Department in the ’seventies, has almost finished work on the official PIRSA geology map of McLaren Vale, due for publication soon. I have assisted in this publication, having first dreamed of it with some of these clever men in the SA Geological Survey all those years ago.

This map will fairly quickly unlock many of the mysteries of the flavours of the region, replace most of the winemakers’ preoccupation with dandruff, instantly begin to influence grape prices, and therefore land prices, and will play a major role in future town planning and development issues. I trust that Premier Rann’s Thirty Year Plan for greater Adelaide will be sufficiently flexible to absorb these realities, which have been there a helluva lot longer than he has.

Unlocking The Rocks

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CONTRIBUTION TO THE 2008 GREENOCK CREEK VINEYARDS AND CELLARS NEWSLETTER

by PHILIP WHITE – September 2008

Time for some rough science. While global warming is such a hot topic cough cough it seemed perfectly appropriate to take a little geology lesson: geology shows we’ve had global warming before. So, like, how bad can things get?

Before you check out Snowball Earth on Wikipedia, let me quote a report of Hoffman, Kaufman, Halverson and Schrag, suggesting one of the things that happened at the bottom of the Neoproterozoic groups which underly Greenock.

“… biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level….resulting in a warming of the snowball Earth to extreme greenhouse conditions. The transfer of atmospheric carbon dioxide to the ocean would result in the rapid precipitation of calcium carbonate in warm surface waters, producing the cap carbonate rocks observed globally.”

I’m sure they make a big difference, but there were no Hummers in those days.

It was also high time the Barossa seriously compared local wines according to their geological sites. But fearing that they may end up with a geology somehow less desirable than others, some vignerons have opposed such an approach for decades. Their excuse? They say they don’t want an appellation imposed like those of France. My response? It’s not a man-made imposition. It’s in the ground beneath you. It was there first.

So a highlight of my thirty years of wine writing finally exploded like a firework, when, in June, I was invited to assist the Barossa winemakers assemble a blind tasting of 52 unfinished 2008 shiraz wines from across the breadth and length of the Valley, from Lyndoch to Kalimna. These were tasted in brackets roughly according to their geological sources, as set out in The Geology of the Barossa Valley, a brochure and map by revered government geologist, W. A. Fairburn. This work, which has the authority of having been gnawed over by the author's scientific peers, is available from Primary Industry and Resources SA. We also had input from the contrary geologist-turned tea-trader turned wine-merchant turned wine-blogger David Farmer, who is writing a book on Barossa geology, and who disagrees with some of Fairburn's mapping.

The tasting was astonishing, while predictable enough. Neighbouring vineyards in each precinct offered flavours and aromas in common, and these characteristics changed from precinct to precinct. This pioneering tasting, conducted with thirty wine writers from around the world, will no doubt be the first of many such exercises, and marks the beginning of a whole new database of gastro-geology.

The base rocks around Seppeltsfield, the Greenock Creek homestead, and Roennfeldt Road are all from that Neoproterozoic, the geological era in which multi-cellular life first appeared. This era stretches from about 550 million years ago to 1.2 billion years. Just for reference, the Universe seems about 13 - 15 billion years old; Earth about 4.5 billion. While these old rocks are generally below the topsoil, they do extrude, and have of course influenced and added to the formation of much of that soil, which very directly influences the flavours of the grape.

But it’s those base rocks that really interest me, particularly when I read back labels and brochures claiming “our vines are grown in some of the oldest soils on Earth”. Most of the Barossa geology formed in the Tertiary and Quaternary, the last 50 million years; its soils are only tens of thousands of years old: most of them are such recent alluviums they’re barely soils at all. “To the geologist, soil is the dandruff of the Earth”, my friend Wolfgang Preiss, Chief Geologist of the Geological Survey in PIRSA, sagely uttered on a recent field trip.

The Greenock Creek vineyards are on four quite distinct formations. The creeklines, both at the homestead and Roennfeldt’s, are very recent alluviums, just tens of thousands of years old. The cabernet, the Creek Block shiraz, and most of the Apricot Block are in such alluviums. These deposits fill the creeklines between the sharply-dipping older strata which protrude in the ridges.

These include the blue-grey dolomitic siltstones - Willunga slate, for example - of the Tapley Hill Formation, deposited as sediments in still deep lakes that once covered the area about 750 million years ago. The Seven Acre and part of the home blocks are in this formation.

Below that lies the Yudnamutana Subgroup. This dark mix of siltstone-derived soil with blotches of bright quartzite and pebbly dolomite is up to 800 million years of age. These layers reappear in Clare and the Adnyamathanha country of the North Flinders. They are pocked with dropstones, which were deposited by floating glacial ice floes. These rocks were one of the fascinations of the great geologist and explorer, Sir Douglas Mawson. Alice’s and part of the Apricot Block are in Yudnamutana.

The Hopeless Hill, on Roennfeldt’s, is on the border of the Yudnamutana and the underlying Burra Group, where we get to really ancient glittery micaceous schists, metasiltstones, calcsilicates and quartzites. These are as old as it gets in the Barossa. The Roennfeldt shiraz, cabernet and the Cornerstone Grenache are in Upper Burra.

In geology, there are many arguments. But having finally got this sorted better than ever before, I’ll never approach Greenock Creek wines in the same way. The distinguishing characters of each vineyard already make much more sense, and the differences between the Greenock Creek/Marananga/Seppeltsfield/Roennfeldt vineyards and the much younger formations in the rest of the Valley become even more meaningful.

So that’s the ancient history. Contemporary history includes the salination, through introduced irrigation water, of the young creekline sediments and clays. And, of course, it includes current weather and climate. People are finally beginning to understand my salination theories. Now, the pace at which the climate is changing must force closer investigation, much quicker than anybody has imagined necessary. If, in a couple of decades, man can change the soil sufficiently to kill a vineyard, like the poor old Creek Block, never irrigated, but dying through salination from upstream irrigators, we can surely bugger up our air.

Or maybe old Mother Earth will just carry on doing what she did before. Now and again, as geology shows, something makes her lose her cool.

PS.

Just to put all this perspective, Don Francis, professor of geology at McGill University in Montreal, has since reported in Science journal that his team has found a sample of Nuvvuagittuq greenstone on Hudson Bay that they believe is 250 million years older than any other rocks known.

"The rocks contain a very special chemical signature - one that can only be found in rocks which are very, very old," he said. "Originally, we thought they were maybe 3.8 billion years old. Now we have pushed the Earth's crust back by hundreds of millions of years. That's why everyone is so excited."

Before this study, the oldest whole rocks were from a 4.03 billion-year-old body known as the Acasta Gneiss, in Canada's Northwest Territories, and the oldest Australia had to offer were 4.36 billion years old mineral grains called zircons from Western Australia.

The greenstone contains fine ribbon-like bands of alternating magnetite and quartz, typical of rock precipitated in deep sea hydrothermal vents - which have been touted as potential habitats for early life on Earth.

"These ribbons could imply that 4.3 billion years ago, Earth had an ocean, with hydrothermal circulation," said Francis. "Now, some people believe that to make precipitation work, you also need bacteria. If that were true, then this would be the oldest evidence of life. But if I were to say that, people would yell and scream and say that there is no hard evidence."

(This additional information was taken from http://news.bbc.co.uk/2/hi/science/nature/7639024.stm )

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