Geology As a Component of Vineyard Terroir in the Western Cape Province, South Africa
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GEOLOGY AS A COMPONENT OF VINEYARD TERROIR IN THE WESTERN CAPE PROVINCE, SOUTH AFRICA CHRIS BARGMANN CGeol FGS, CAPE WINE MASTER 35th IGC, CAPE TOWN AUGUST 2016 The South African Wine Industry Vines first grown in Cape Town in 1659 by the Dutch East India Company. 2015 wine grape vineyards 98,597 ha (Australia 148 000 ha). Most planted varietals (2015) - Chenin Blanc, Colombard, Cabernet Sauvignon and Shiraz. Less regulation since 1985 – new viticultural areas developed (Elgin, Hamel en Aarde, Darling), less dependence on the co-operative winery system, more experimentation with cultivars, soils and sites. Post 1994 – international markets available, however wines received a mixed reception. Today a combination of a better understanding of local Terroir, replanting with varietals to match vineyard sites, increasing numbers of “old vine” & site specific wines and a new generation of progressive winemakers has resulted in South Africa’s wines attracting both local and international acclaim. Grape Varietals and Growing Areas 2000 2005 2010 2015 Wine Grape (Ha) 105,566 101,607 101,016 98,597 2015 Figures Red:White 36:64 46:54 44:56 45:55 SAWIS District Ha % of total % Red % White Stellenbosch 15,911 16.1 22.0 11.0 Chenin Blanc % 24.1 18.8 18.3 18.2 Paarl 15,678 15.9 21.0 12.0 Colombar % 12.2 11.3 11.9 12.0 Robertson 14,264 14.47 13.0 16.0 Sauvignon Blanc % 5.7 7.5 9.5 9.4 Swartland 13,315 13.5 18.0 10.0 Chardonnay % 6.4 7.8 8.2 7.2 Breedekloof 13,029 13.21 11.0 15.0 Olifants River 10,263 10.41 7.0 13.0 Cab Sauvignon % 9.5 13.4 12.2 11.3 Worcester 8,824 8.95 7.0 11.0 Shiraz % 6.0 9.6 10.0 10.5 Northern Cape 4,687 4.75 1.0 8.0 Pinotage % 7.0 6.4 6.2 7.5 Klein Karoo 2,625 2.66 1.0 4.0 Merlot % 5.2 6.8 6.4 6.0 Cinsault % 3.7 2.8 2.0 1.9 Pinot Noir % 0.6 0.5 1.0 1.1 45% Red : 55% White South African Wine of Origin system comprises; 6 Regions (largest) – 24 Districts – 63 wards (smallest) Western Cape Province – Wine Regions From www.sawis.co.za Western Cape Province – Wine Districts From www.sawis.co.za Western Cape Province – Wine Wards From www.sawis.co.za Terroir in the Western Cape Province Climate - Winter rainfall area, Diurnal temperature variation, Sea breezes, Soil – Structure, Drainage, Water retention ability, Alluvial gravels. Geology – Granite – acid soils + kaolin, Shale – better structured soils, Karoo – calcareous soils. Aspect – Altitude, Slope orientation, Warm or cool slopes - sunlight exposure, Wind exposure. Plus - Viticulture and Winemaking practices Western Cape Province Terroir – Climate From www.wosa.co.za Western Cape Province Terroir – Rainfall From www.capewatersolutions.co.za Western Cape Province Terroir – Aspect & Topography Altitude Sunlight exposure, Exposure to sea breezes Western Cape Province Terroir – Geology Late Proterozoic – Malmesbury Group. Marine sediments, predominantly shaley, some conglomerates rare limestone's. Cambrian – Cape Granite Suite. Cambrian – Klipheuwel Group. Shale and conglomerate. Middle Ordovician to Early Carboniferous – Cape Supergroup. Table Mountain Group sandstones, Bokkeveld Group sandstones & shales, Witteberg Group sandstones & shales Late Carboniferous to Permian – Karoo Supergroup. Dwyka tillite, Ecca Group shales Upper Jurassic– Uitenhage Group. Enon conglomerate Early Cretaceous – False Bay Dolerites Western Cape Province Terroir – Geology Alluvial soils and terraces. Residual soils, often loams and duplex types. Formation of kaolin and saprolites within granites. Formation of calcareous deposits within soils in dryer areas. Aeolian soils. River gravels and soil formation have been ongoing for the whole Cenozoic, resulting in soils of great antiquity. Western Cape Province Terroir – Geology Wine region / district Age Supergroup Group Formation Main rocktypes Major geological events Cainozoic Residual soils, alluvium, scree Early Cretaceous (False Bay Dolerites Dyke Swarm) Dolerite 136 Ma U Jurassic - E Cretaceous Kirkwood Formation Sandstone, shale, bentonite Gondwana age faulting Uitenhage Group 139-123 Ma Enon Formation Conglomerate Major unconformity Permian Waterford Formation Sandstone, siltstone, shale, mudstone Cape Orogeny - Cape Fold Belt (275 - 265 Ma) Tierberg Formation Shale, claystone, mudstone, siltstone Ecca Group Collingham Formation Shale, siltstone, mudstone, tuff Karoo Supergroup Whitehall Formation Shale, tuff Prince Albert Formation Shale Late Carboniferous - Permian Dwyka Group Diamictite (302 - 290 Ma) Glaciation, major unconformity Middle Devonian - Early Carboniferous Waaipoort Formation Shale, mudstone, siltstone (387 - 327 Ma) Floriskraal Formation Sandstone, siltstone, sandy shale Kweekvlei Formation Shale, siltstone Witteberg Group Witpoort Formation Sandstone Swartruggens Formation Siltstone, mudstone, sandstone Blinkberg Formation Sandstone Wagen Drift Formation Siltstone, sandy shale, mudstone, sandstone Early Devonian - Mid Devonian Karoopoort Formation Siltstone, sandy shale (409 - 387 Ma) Osberg formation Sandstone, Klipbokkop Formation Siltstone, mudstone, sandstone Wuppertal Formation Sandstone, siltstone, shale Waboomberg Formation Siltstone, shale, mudstone, sandstone Bokkeveld Group Boplaas Formation Sandstone Cape Supergroup Tra-Tra Formation Shale, mudstone, siltstone, sandstone KLEINREGION KAROO Hex River Formation Sandstone Voorstehoek Formation Mudstone, shale, siltstone BREEDERIVER REGION Gamka Formation Sandstone, siltstone Gydo Formation Shale, mudstone, siltstone OLIFANTSRIVERREGION Mid Ordovician - Early Devonian Rietvlei Formation Sandstone, siltstone, shale (450 - 409 Ma) Skurweberg Formation Sandstone Goudini Formation Sandstone, siltstone, shale Cederberg Formation Shale Table Mountain Group Glaciation Pakhuis Formation Diamictite, sandstone Peninsula Formation Sandstone Graafwater Formation Sandstone, siltstone, shale Piekenierskloof Formation Sandstone, conglomerate Major unconformity CAPESOUTHCOAST REGION Middle Cambrian Populierbos Formation Mudstone Kilpheuwel Group (520 - 510 Ma) Magrug Formation Conglomerate, sandstone Early - Middle Cambrian Igneous activity Cape Granite Suite Granite, Granodiorite, Gabbro, Diorite (550 - 515 Ma) Late Proterozoic - Early Cambrian Brandwacht Formation Greywacke, conglomerate, volcanics Saldanian Orogeny (780 - 550 Ma) Porterville Formation Shale, greywacke, minot limestone Norree Formation Greywacke, quartzite, minor limestone, dolomite Piketberg Formation Grit, conglomerate, greywacke Franschhoek Formation Conglomerate, quartzite Malmesbury Group COASTALREGION Tygerberg Formation Greywacke, shale, siltstone, quartzite Bridgetown Formation Moorreesberg Formation Greywacke Klipplaat Formation Quartz schist Berg River Formation Mica schist, greywacke Western Cape Province Terroir – Geology Western Cape Province Terroir – Geology High rainfall in the west. Dry in the east. Heat summation decreases 550 mm northwest - southeast 2249 degree days Large diurnal variation in the south with breezes from SE and mist forming in the river valley. Varied geology, calcareous 200 mm 780 mm soils and alluvial. 1980 degree days 2076 degree days 280 mm 2181 degree days 327 mm 1968 degree days Western Cape Province Terroir – Geology Tulbagh Durbanville Darling Malmesbury Group Western Cape Province Terroir – Geology Paarl Pluton Cape Pluton – Kaolin formation Kuils River – Helderberg Pluton – Hornfels shale hills on pluton edge Cape Granite Suite Western Cape Province Terroir – Geology Elgin Hamel en Aarde Valley Elgin Bokkeveld Group Western Cape Province Terroir – Geology Nuy – Robertson – Cretaceous Enon Conglomerate Permian Dwyka Tillite based red soil based red soil Karoo and Uitenhage Groups Western Cape Province Terroir – Geology Breede River Valley Cape Pluton Soils Western Cape Province Terroir – Geological Influences Granite – Acidic, clay rich soils. Kaolin locally significant. Malmesbury Group – Shale / greywacke dominated. Acidic, clay rich soils. Hornfels important on pluton edges, rare limestone's present. Table Mountain Group – Sandstones rarely used for vineyards. TMS derived sand is a common component in many vineyard soils. Breede River Region - Loamy calcareous soils, associated with Bokkeveld & Witteberg shales, Dwyka tillite and Enon conglomerate. Only area with significant alkaline soils. River gravels commonly utilised in dryer areas where irrigation water is available. Topography, altitude and slope orientation Western Cape Province Terroir – Geological Influences Shiraz – Granite preference? Merlot, Chenin Blanc – Shale preference? A Personal Selection of Terroir Driven Western Cape Wine Producers Note: Not all vineyards are open to the public, check before visiting. Constantia - Cape Point Vineyards. Cape Granite based soils, on south facing slopes of the Constantiaberg. Unique south facing setting. Sauvignon Blanc. Durbanville – Diemersdal Estate. Malmesbury shale based soils in the Durbanville hills. Cooling Atlantic sea breezes contribute to the iconic Sauvignon Blanc. Stellenbosch – Kanonkop Estate. Granite based soils on the western slopes of the Simonsberg. Benchmark South African Pinotage, also Cabernet Sauvignon. (also - Hartenberg, Tokara, Vergelegen) Elgin - Paul Cluver. Bokkeveld shales in the upland Elgin valley. Cooler climate apple growing area. Chardonnay and Pinot Noir. Hemel en Aarde Valley – Hamilton Russell Vineyards. Pioneer producer from the 1980’s. Bokkeveld shales, breezes from the Walker Bay. Pinot Noir and Chardonnay. (also – Strandveld (Elim)) A Personal Selection of Terroir Driven Western Cape Wine Producers