The recent Geology and Grasses field trip challenged participants to look at the natural environment broadly.
On 25 February 2023, a group of seven set off to explore the geology and grasses of Verloren Valei. The field trip was led by Dr Trevor Pearton, a geologist, and Mike Zingel, a former chairman of Friends of Verloren Valei and an expert in veld management. Both gentlemen have previously led field trips at Verloren Valei focused on their respective specialities.
The reason for combining the two topics of grass and geology was to prompt a more holistic way of looking at the natural environment, said Dr Pearton during the presentation he and Mr Zingel gave at the beginning of the field trip. The underlying geology influences what grows on the surface while, in turn, what grows on the surface affects the geological processes.
Dr Pearton provided a commentary on the geological events that led to the formation of Verloren Valei—a unique high-altitude wetland. To cut a long story short, the superheating of the Steenkampsberg Quartzite by lava flows resulted in the creation of brittle, glassy rocks that protected the softer diabase (derived from lava) from eroding. At the same time, the brittle indurated quartzite developed characteristic fractures which allowed surface water from rain to penetrate into the diabase, creating wetlands.
It is this hard, weathering-resistant backbone that underpins the development of Verloren Valei’s wetlands.
The fractured, glassy quartzite is easily seen on the surface at various places on the reserve.
Mike Zingel’s presentation looked at the way in which grasses established themselves in the area following the breakup of the Gondwana landmass approximately 120-170 million years ago. He then went into some detail explaining what the main parts of the grass plant are, and what their functions are.
One of his main points was the intricate symbiotic relationship that exists between the grasses and the bacteria and mycorrhiza fungi that live amongst their roots. The plants secrete carbohydrates for the bacteria and fungus to eat, which the latter repay by converting atmospheric nitrogen and fixed phosphorus into compounds that the plants can use.
This symbiosis is also critical in many of the indigenous orchids found on the Reserve.
Mr Zingel concluded that the grasses play a major role in stabilising and conserving the wetland. They also act as a highly efficient carbon trap–in fact, a rough calculation indicates that the carbon sequestered in Verloren Valei’s soils is equivalent to the carbon emitted by 3 360 return flights to Europe.
After the presentation, the group spent several hours in the field looking at examples of what had been described in the presentations.
Heartfelt thanks to both gentlemen for sharing their expertise and insights with us—it is these excursions that deepen one’s understanding of Verloren Valei.