Hiking the Tswaing Meteorite Crater Near Pretoria
I have lived in Pretoria, South Africa, for most of my life, but it took a visit from a Canadian family member to get us packing a picnic and putting on our walking shoes to visit this impact crater about 40 km from the city.
It is a cold winter’s morning, but we are getting quite hot as we walk along the rim of the Tswaing Crater. Armed with the hiking trail map, oranges, Sally Williams nougat, and water, we have set out on the 7km walk 30 minutes earlier and have just caught a glimpse of the fascinating crater below.
A 'Star' Attraction
The history of the crater starts 220 000 years ago, when a stony meteorite hit the earth with a force 100 times more powerful than the Hiroshima atomic bomb blast(1). The meteorite of 30 to 50 m in diameter vaporised in the explosion, causing the crater which is 1.3km in diameter and more than 100m deep. The meteorite was chondritic (stony) in composition, unlike the iron-rich meteorites associated with many other small impact craters.
In 2009, a fire gutted the museum building. This must have been a major setback in the quest to get the museum declared a World Heritage Site, which was submitted as a “tentative site” in 2004 and has stayed fixed on that status ever since.
The “star” attraction however is the crater itself, and numbered stone slabs with succinct information reminding us that the crater really is the museum. There is evidence of Middle Stone Age hunting, gathering, and salt collecting; salt production by Sotho- and Tswana-speaking communities AD 1200 to 1830; ox wagon trails of the 19th century; soda ash and salt mining from the 19th century to about 1950; and research activities from the second half of the 20th century.
One Point in Space; So Many Points in Time
I imagine being alive 220 000 years ago, watching the miraculous stone fell from the sky. How would my Middle Stone Age brain have perceived this phenomenon? Would I have communicated the event to my grandchildren and would we commemorate the date each year? As a Middle Stone Age woman, I wouldn't have depicted the event through rock art, which is only found in South Africa 170 000 years later than this event.
One point in space, so many points in time.
We start in the 20th century, with old cattle pens and trenches carrying the pipeline between the crater and the soda and salt reduction works, past the Shoemaker viewpoint, where we realise that we are standing on boulders that were ejected by the force of the meteorite impact: 60m above the surrounding veld (behind us) and 100m above the crater floor.
At Crater Level
Down at crater level, we stop for a picnic. We hear the chatter of children on a school outing as they climb down the only mildly difficult part of the hike. The noise subsides as they pass us, walk round the crater and stop to taste the salt deposits at the edge of the water. On the other side of the crater, we intersect AD 1200 to 1830 where fragments of clay pots from Sotho- and Tswana- speaking communities were found, where they produced salt by filtering, boiling and evaporating the lake water. It is evident that the small lake is fuller in summer than in winter, and we learn that the water is replenished both by a spring in its basin and by rainwater. Apparently the salt content has dropped and the crater is no longer viable for salt mining.
Recent bore holes were drilled to explore the sedimentary deposits below the crater floor. In 1989 geologists drilled 200m down and findings confirmed that Tswaing was the result of a meteorite and not a volcanic event . The drill core also revealed other information: past climatic conditions – interchanging between dry and wet conditions (even a forest of yellowwood trees); the age of the crater; and some information about the probable animal and human life during and after the impact.
The rest of the walk is all about the salt: pumping stations; whitewash, with which they tried to change the colour of the brown salt to white; ruins of the reduction works and ponds where the liquid from the crater was transformed to soda ash and salt.
These ruins are fascinating.
We ignore the warning of snakes – it is winter after all – and investigate the reservoirs.
Could they be renovated somewhat more to create the picture of how the facility functioned 60 years ago? On the internet I found an interesting thesis from an architectural student investigating how this could be done.
The Crater site is also a nature reserve, covering 2 000 hectares, with more than 300 bird species and over 400 floral species and including a stream feeding a rare and extensive wetland system. More to explore for our next visit.
How to Get There
Tswaing is on the M35 about 40km north of Pretoria.
Take the N1 north past Pretoria towards Polokwane. Drive past the Zambesi Drive/Cullinan off-ramp. At the next off-ramp take the N4 west towards Rustenburg. Drive west for 19 km.
Take the M80 Pretoria/Soshanguve off-ramp and head north towards Soshanguve for about 18 km until you reach a three-way stop intersection. Turn right towards the M35 Soutpan. Turn left at T-junction with the M35. You will find signage for Tswaing here.
Drive north for about 15km through Soshanguve’s informal settlements. Turn left at the brown tourist sign to the Tswaing visitors’ centre to buy the entry permit. Drive out again, left onto the M35 north and then immediate left into the dirt access road, which ends in the picnic site and start of the hike.
More About The Tswaing Crater
- Ditsong Museums of South Africa
- Manifesting the Memory: A Memorial for the Meteorite
Bredell, A 2009, Manifesting the memory : a memorial for a meteorite, University of Pretoria, Pretoria.
- Environmental Effects of the Tswaing Impact Event