IN THIS ISSUE
- Talk by Mike Bruton: 20 July at 17h30
- Wetland education
- Expos on Fynbos
WHEN DARWIN VISITED THE CAPE OF GOOD HOPE…
A Talk by Prof Mike Bruton Thursday 20 July 17h30 at the Green House
By way of introduction to this talk by Mike Bruton, let us set the scene.
Charles Darwin visited the Cape of Good Hope in mid-1836 towards the end of the five- year, round-the-world voyage of the HMS Beagle. Although he was (understandably) exhausted and keen to return home, he made good use of his only landfall in Africa. He travelled widely, made detailed observations on local geology and the fynbos biome, and met several prominent scientists.
Charles Darwin was a man of many accomplishments, and is perhaps best known for his groundbreaking theory outlined in his treatise “On the origin of species”, more descriptively called the theory of evolution by natural selection. So we think of him as a developmental ecologist, although he was actually a geologist by training. Did his visit to the Cape have any impact on the development of his epochal theory of evolution by natural selection?
Indeed, it did. The geological formations he found at the Cape had a profound impact on Darwin’s thinking about the time scale involved in his theory of evolution.
Photo (above right): Zandrivier Farm
One geological feature that influenced Darwin’s thoughts was the presence of marine fossils, similar to species that were still alive in the nearby ocean, found in elevated rock formations. This indicated that the land had once been unde
r the sea and had subsequently been uplifted. This led him to consider the idea that the Earth’s surface had undergone significant changes over vast periods of time. He realised that the uplift and subsequent exposure of these marine fossils had required long periods of geological processes, such as the gradual accumulation of sediment, the subsidence of land, and the forces of uplift, followed by erosion.
On the rocky shore at Sea Point, Darwin noticed evidence of another dramatic geological phenomenon. Once-molten magma had intruded into fissures in the sedimentary rock of the Malmesbury Group. We can still observe the results of this event (believed to have occurred at a depth of some 10 km) frozen before our eyes as they were before his, a complex intermixing of the dark sedimentary rocks with the pink-brown igneous granite.
Darwin’s exposure to the geological formations at the Cape of Good Hope, along with his broader observations from his voyage on the HMS Beagle, contributed to his understanding of the concept of deep time. Deep time refers to the immense time-scales involved in geological and biological processes. The geological evidence suggested to him that the earth had existed for very much longer than the biblical timeline. This provided the necessary time for the slow, gradual processes of evolution to occur – that is, the slow accumulation of small changes within populations over long periods, leading to the gradual emergence of new species.
It’s difficult for us to comprehend how long the 4.5 billion years is that the earth has been in existence. Deep time is not part of our human experience and while we can quote numbers, we don’t really comprehend them. Suffice to say that there has been ample time for organisms to change (initially by chance) and for any beneficial changes to become established in a population if that change makes survival even slightly more likely.
Incidentally, Darwin was not impressed at all with the Cape weather. It was mid-winter, cold, dark and rainy, with bone-chilling winds. His already depressed mood was not lifted by the spectacular beauty we associate with the Fairest Cape.
You are invited to hear more about Darwin’s observations and his understanding and development of his (at the time) revolutionary theories. The always entertaining and informative Mike Bruton will give a talk on “When Darwin visited the Cape of Good Hope” at Whale Coast Conservation on Thursday 20 July at 17h30. All are welcome. Donations at the door will be appreciated.
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WETLANDS EXPOS AT MASAKHANE, DIE BRON & OKKIE SMUTS PRIMARY SCHOOLS
Our Expo on wetlands at Masakhane Primary in Gansbaai allowed us to welcome a delegation from AVI Community Trust on a site visit. Thabile Xulu, CSI Specialist, was accompanied by Mivuyo Msuseni (I&J), Neteske Gerber and Shaun Wessels, Board member of the Trust.
In the photo to the left, Shirley Mgoboza can be seen (back right) with Thabile Xulu (back left) and one of the more spirited groups of Masakhane learners. A total of 108 learners attended the expo.
We offered the same expo on wetlands at Okkie Smuts and Die Bron Primary schools in Stanford. A total of 72 learners from these two schools attended the expo. The learners were well-behaved, enthusiastic, and a pleasure to teach. At the same time they were not averse to a bit of fun.
Volunteer Dr Kathie Buley set the scene for Wonderful, Watery Wetlands.
She stressed the importance of our Wetlands because they purify water, store water, prevent floods, provide a home for special animals and plants, food for livestock, a place for recreation, and have economic potential.
Dr Anina Lee discussed some of the animals, such as frogs and birds that call wetlands their home. An interactive computer programme showing frog pictures linked to the specific calls of the male s, captured the imagination of the learners. The “snoring” sound of the highly endangered Western Leopard Toad caused much mirth.
Sheraine van Wyk discussed the plants that typically grow in wetlands, illustrated by specimens from the Mill Stream in Stanford.
Sheraine also showed a number of exotic or alien plants that are likely to become more invasive when there is nutrient enrichment in the water through pollution. These alien plants out-compete native plants leading to loss of biodiversity.
Volunteer Stephanie Vegter showed the learners where in South Africa we find wetlands.
She explained the concept of Ramsar sites that have particular importance and need for protection. Then the learners tried to find different Ramsar sites on a map of South Africa.
Shirley Mgoboza stressed the importance of water, and the percentage of drinkable water we have for our use.
They looked at the 4 stages of the water cycle and again touched on the negative effects of water pollution of our water bodies from farming activities, factories and households.
We thank the AVI Community Trust for funding these expos on Wetlands.
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FYNBOS EXPO AT HAWSTON PRIMARY
We continued our series of expos on fynbos, funded by the Hermanus Botanical Society. A total of 71 Grade 6 learners attended. We will be returning in the third term to talk to another 70 learners about the uniqueness and importance of our indigenous flora. Here are some pictorial highlights of the expo.
Volunteer Dr Kathie Buley explained what we mean by biodiversity and that the wide variety of species provides ecological resilience against environmental catastrophes like climate change.
Dr Anina Lee stressed the ecosystem services provided by fynbos such as tourism (which drives our economy), the provision of fresh water throughout the year, the cut-flower industry and providing forage for pollinators.
Shirley Mgoboza gave the learners insight into the various threats to fynbos such as climate change, habitat loss due to urbanisation and agriculture, and invasive alien vegetation.
Volunteer Stephanie Vegter put up an amazing display demonstrating pollination of flowers and their pollinators. She explained that pollination is the process by which pollen grains from the male part of a flower (anther) are transferred to the female part of another flower (stigma), leading to fertilisation and the production of seeds. This essential process enables the reproduction of flowering plants and is vital for the production of many fruits, vegetables, and nuts.
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Written by Anina Lee
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