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“Heritage Day and (Hydro)geoheritage”

The unique combination of diverse cultures, beliefs and traditions is celebrated annually by South Africans during Heritage Month in September, and specifically Heritage Day on the 24th September. What a lot of South Africans do not know about, however, is the equally unique and diverse geological heritage (“geoheritage”) of the country that covers 3.6 billion years of Earth’s evolution, and how this geoheritage strongly influenced the history, culture and development of South Africa. Other than the world famous Table Mountain (which lends its name to the geologically and hydrogeologically famous Table Mountain Group [TMG]), the Western Cape province has a range of interesting geoheritage sites, including important fossil localities such as the Devonian (~390-375 million years old) Bokkeveld Group and the Late Miocene/Early Pliocene (~5 million years old) West Coast Fossil Park.

Umvoto’s Principal Geologist Dylan Blake enjoying the much-loved South African tradition of braaiing.

An important aspect of geoheritage, namely groundwater or hydrogeological heritage, has played a major role in the development of Cape Town (and the Western Cape province as a whole). The springs that discharged from the base of Table Mountain in the now City Bowl and Newlands-Wynberg areas resulted in the region being settled by the pastoral Khoi-Khoi in the 1000s (and for thousands of years prior to this by the nomadic San), who named the area “Camissa” (“the place of sweet waters”) and Table Mountain “Hoerikwaggo” (“mountain in the sea”). These springs were also the reason for the Dutch setting up a halfway supply station at Cape Town in the 1600s for VOC ships travelling to and from Europe and Southeast Asia, and are still utilised today. There are approximately 100 springs within the City of Cape Town municipal boundaries of variable yield and geological setting, which provide water for municipal supply (e.g. the Albion Spring in Rondebosch, Silwerstroom Spring near Atlantis, and major City Bowl springs), beer brewing (e.g., Newlands Spring) and small scale residential use (e.g., St James springs along Main Road in the South Peninsula, and Newlands Spring as well).

One enjoyable activity which crosses all cultures in South Africa is braaiing, with the 24th September also being “National Braai Day”. For those not stoking the coals at home with friends and family, a long weekend away at one of the Western Cape’s hot springs is a good place to celebrate the country’s heritage over the fire after a dip in geothermal waters. The TMG-dominated structural and geochemical setting of these unique geothermal springs (which includes the hottest natural geothermal spring in South Africa at 64°C, Brandvlei) adds to their fascinating (hydro)geoheritage and history.

Brandvlei geothermal spring within Brandvlei Correctional Centre near Worcester, which is the hottest natural spring in South Africa.

While waiting for the coals to be ready, or turning whatever favoured foodstuff is being cooked on the grid, South Africans usually enjoy consuming a cold beverage of their choice. Even that tasty beer or glass of wine has a strong geoheritage and hydrogeological link though, with the “terroir” of both vineyards and hops playing a significant role in the types of wine and beers produced, respectively. The geology, and associated landforms, soils and microclimates, result in a range of excellent, world renowned wines from the Western Cape. Groundwater also plays a significant role in providing irrigation water to vineyards and hops. The Waboomskraal valley at the top of the Outeniqua Mountains between George and Oudtshoorn, which is comprised of structurally deformed TMG rocks, comprises almost all South Africa’s hop farms (and are some of the most-southern hops farms in the world). These hops are irrigated either by groundwater abstracted from the fractured TMG aquifers, or surface water discharge from the TMG-dominated Outeniqua Mountains. So this Heritage/Braai Day, raise a glass to the (hydro)geoheritage underneath your feet and in the mountains around you.

Vineyards near Rawsonville on Breede River valley alluvium along the base of the TMG-dominated Slanghoekberge.
Hop farms within the Waboomskraal valley, and basic TMG geological and structural setting of the valley.

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muizenberg, Cape town