This article is from
Creation 40(1):44–47, January 2018

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The Vredefort Dome, South Africa

Formed by an enormous asteroid impact during a global watery catastrophe

by

V-Dome

The village of Vredefort (pronounced: free ED duh fort = ‘peace fort’) southwest of Johannesburg in South Africa sits at the middle of what is widely regarded as the largest impact structure on Earth. It nestles in a beautiful farming area with rolling hills, ridges, and valleys. The Vaal River, which marks the boundary between the provinces of North West and Free State, winds across the country and between the surrounding mountains. (figure 1)

Johan SmitVaal-river
 Figure 1. Inside the Vredefort Dome with the Vaal River flowing towards the surrounding mountains.

A change in perspective

For more than 100 years, the origin of the Vredefort structure has been controversial. Initially it was thought that volcanic magma (melted rock) welling up from beneath the earth’s surface formed the circular feature.1 This explanation was driven by the doctrine that geological features must be explained by the slow processes we observe today operating over enormous expanses of time. It was considered geological heresy to use a process not natural to the globe, or to invoke an extraordinary event. Consequently, well into the mid-20th century, extraterrestrial impacts were considered taboo.2

Despite this, beginning in the first half of the 20th century, some scientists began suggesting that various circular features on Earth, including the Vredefort ‘ring’, looked like they had been formed by asteroid impacts. This idea eventually became widely accepted but controversy continued in South Africa until the mid-1990s.1 Over many years different techniques were used to assemble evidence for an impact origin of Vredefort, including mapping the geology of the area, recording the distribution of metamorphic rocks (rocks that have been changed by heat, for example), and modelling the impact on computers. Eventually people were persuaded, and in 2005, the Vredefort Dome was World Heritage listed as the world’s largest impact structure.3

Evidence for the impact

When you visit the area, the impact structure is not immediately obvious because of its enormous size and erosion. It is only from satellite images (figure 2) and geological maps (figure 3) that the 80-km (50-mile) diameter semi-circular ring of mountains looks like an impact structure. This ring, however, is considered to be just the inner portion of the crater. There is a larger 300-km (200-mile) structure,4 extending to Johannesburg and beyond, and this is even less evident. One complicating factor is that much of the structure has been eroded away.

NASA PhotoSTS511-3356AAV-dome-from-space
Figure 2. The Vredefort Dome from space. The Vaal River runs through the semi-circular ring of mountains. Width of image = 80 km (50 miles).

According to calculations, the asteroid that formed Vredefort would have been around 10 km across,5 making it one of the largest ever to smash into the planet. When it hit, the land surface there was 7–10 km higher. Within seconds, the meteor penetrated kilometres into the earth’s crust, pushing it down. The crust then rebounded, uplifting rocks that had been deep underground, forming a ring of hills, like a collar, around the inner part of the crater—the Vredefort ‘Dome’.6 The ring of hills is composed of metamorphosed layers that now sit almost vertically. They include gold-bearing quartz-conglomerate layers, kilometres thick, which are part of the famous Witwatersrand Supergroup. Some century-old abandoned mine shafts still exist in the ring of hills.

The area inside the ring is granitic rock (figure 3), which forms the basement of the area. Before the granite rebounded, it sat more than 20 km (10 miles) beneath the surface.4 The force of the impact deeply fractured the granite, and partly melted it. Some magma was rich in iron and magnesium and filled the cracks, enveloping chunks (clasts) of broken granite, and solidifying into a black, glassy rock called pseudotachylite (soo DO tacky lite). Because it has been found at a number of impact sites around the world it has been taken as evidence for the asteroid impact. Leeuwkop Quarry near Parys shows magnificent exposures of pseudotachylite enveloping large, rounded chunks of granite (figure 4).

map-Vredefort-Dome
 Figure 3. Simplified geological map of the Vredefort Dome (from ref. 1, p. 121). The granitic Archaean basement in the middle of the dome was uplifted just after the impact. The Witwatersrand, Ventersdorp and Transvaal rocks, which were deposited before the asteroid struck, were uplifted to form the ring of mountains around the dome. The Karoo Supergroup was deposited later, and then mostly eroded.
pseudotachylite
Figure 4. Black, glassy pseudotachylite exposed at Leeuwkop Quarry filling large fractures in the basement granite and containing large, sometimes rounded chunks of granite. Credit: Johan Smit.
Granophyre-dyke
 Figure 5. Granophyre dyke within the the Vredefort Dome outcropping as a line of broken rocks.

Other magma was rich in silica and aluminium. This flowed into other cracks forming a light coloured rock called granophyre (GRAN oh fire), which is exposed as a number of long dykes in the area (figure 5). These dykes and the pattern they form are also evidence for the impact.7

A common feature in the upturned rocks around the dome is shatter cones—a fracture pattern resembling a fir tree (figure 6). These have been discovered at other impact sites, and are interpreted as being caused by high pressure shockwaves from the impact.

These and other evidences have persuaded people to accept that the structure was formed by an asteroid.

Geological catastrophe

An asteroid impact means that enormous geological changes happened very quickly. We are not talking about a million years, or even one year, or a day. Within a few seconds, a primary crater more than 100 km (60 miles) in diameter and 20 km (12 miles) deep would have been excavated. The crust rebounded after a few more seconds, tipping sediments kilometres thick vertically up and around an uplifted central dome. Then the dome began to collapse, and the whole crater of 300 km (200 miles) would have been completed in 10 minutes or so.8

fir-tree
Figure 6. Shatter cones in the granite with their characteristic ‘fir tree’ fracture pattern (key for scale). Credit: Johan Smit.

All this is said to have happened very early in the geological history of South Africa. The primary way the timing is worked out is through geological relationships (figure 3), some of which are visible on the schematic cross section of figure 7. The granitic basement existed first, before a thick sequence of sedimentary and volcanic layers was deposited in a watery environment—the oldest layer at the bottom and the youngest at the top. The asteroid struck the uppermost layer, deformed all the layers and the basement, formed the crater, blasted ejecta (debris) from the crater, and uplifted the central dome.

Long-age geologists have assigned a date of 2,023 million years ago for the impact, based on measurements of isotopes of uranium and lead in some zircon crystals collected from the pseudotachylite and granophyre dykes.9 While the relative ages of the rocks are soundly based on observable field relationships, the claimed ‘absolute’ ages obtained from the isotopic dating methods are not objective. These are based on multiple assumptions, including about the initial concentration of isotopes, and the effects of subsequent geological disturbance on the samples, of which there were many. Unravelling the effect of all these disturbances on the isotope relationships within each zircon is speculative. The different numbers obtained from the different samples are ‘interpreted’ after the event to create a narrative—one that fits the field relationships and the assumed long-age scenario for Earth history.10 Because long-age dates are so subjective, it is possible to develop a different narrative—one that fits a biblical scenario for Earth history.

The asteroid impact would have occurred early in Noah’s Flood.11 We say it was during the Flood and not Creation Week because everything at the beginning was “very good” (Genesis 1:31). An asteroid impact would have filled the atmosphere with deadly ash and dust, which would not have been good. But the impact would not have initiated the Flood because the layers of rock deposited before the impact would also have been deposited early in Noah’s Flood. These include deposits of basaltic lava kilometres thick in a sequence called the Ventersdorp Supergroup.12 Huge outpourings of volcanic lava would have contaminated the atmosphere with toxic fumes, and not been “very good” either. In fact, these outpourings were too large (in thickness and geographical area) to have occurred after the Fall and before the Flood; human life would not have survived such massive volcanic contamination without the relative protection of the waters of the Flood blanketing the eruptions.

After the impact, geological upheavals continued, forming such features as the Bushveld Complex, the Cape Supergroup and the Karoo Supergroup,13 as the waters of the Genesis Flood were rising. In this period rocks were folded and eroded on several occasions.

After the waters eventually covered the whole continent, kilometres of thickness of rock were eroded as they receded, forming the Great African (Planation) Surface,14 and exposing the Dome. With further drops in the water level the reduced flow cut curious drainage patterns around the Dome, including numerous water gaps through the tilted ring of mountains, through which the Vaal River flows today. Slow erosion over millions of years does not explain these patterns, but the receding waters of the Flood do.

After Oggmus, Wikimedia commonsschematic-cross-section
Figure 7. A schematic cross-section (not to scale) of the Vredefort impact crater from the northeast (left) to the southwest (right). The top portion has been eroded away to the present land surface. Johannesburg is shown on the left sitting at the present surface where the Witwatersrand Supergroup (yellow layer) is exposed, just inside the crater rim.

Conclusion

The Vredefort impact crater, of which the Vredefort Dome represents the inner portion, formed early in Noah’s Flood. The size of the impact demonstrates the enormous catastrophic forces that shook the earth at that time. The folding and uplift of the sediments produced by the impact took place in a very short period of time—less than a day. As the Flood catastrophe continued, not only did it deposit thick sequences of sediments and volcanic lava on top of the impact crater, but it subsequently eroded them away, exposing the deep impact structure at the surface, along with the uplifted sediments of the famously gold-rich Witwatersrand Supergroup.

References and notes

  1. Reimold, W.U. and Koeberl, C., Impact structures in Africa: A review, J. Afr. Earth Sci. 93:57–175, 2014, p. 119 | doi:10.1016/j.jafrearsci.2014.01.008; 1464343X1400017X. Return to text.
  2. Marvin, U.B., Impact and its revolutionary implications for geology; in: Sharpton, V.L. and Ward, P.D., Global Catastrophes in Earth History; An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Geological Society of America Special Paper, 1990. Return to text.
  3. Proposal: Vredefort Dome World Heritage Site, Free State Province, Republic of South Africa, Department of Tourism, Environment and Economic Affairs, 2005; unesco.org. Return to text.
  4. Therriault, A.M., Grieve, R.A.F., and Reimold, W.U., Original size of the Vredefort Structure: Implications for the geological evolution of the Witwatersrand Basin, Meteorit. Planet. Sci. 32:71–77, 1997. Return to text.
  5. .Reimold and Koeberl, ref. 1, p. 124. This assumes the asteroid impacted a solid earth. Return to text.
  6. Norman, N. and Whitfield, G., Geological Journeys: A traveller’s guide to South Africa’s rocks and landforms, Struik Nature, Cape Town, pp. 60–61, 2006. Return to text.
  7. Therriault, A.M., Reimold, W.U., and Reid, A.M., Geochemistry and impact origin of the Vredefort Granophyre, SAJG 100(2): 115–122, 1997. Return to text.
  8. .Reimold and Koeberl, ref. 1, p. 74. Return to text.
  9. Reimold and Koeberl, ref. 1, p. 127. Return to text.
  10. Spray, J.G., Kelley, S.P., and Reimold, W.U., Laser probe argon-40/argon-39 dating of coesite- and stishovite-bearing pseudotachylytes and the age of the Vredefort impact event, Meteoritics 30:335–343, 1995 | doi: 10.1111/j.1945-5100.1995.tb01132.x. Return to text.
  11. Oard, M.J., Precambrian impacts and the Genesis Flood, J. Creation 28(3):99–105, 2014;creation.com/precambrian-flood. Return to text.
  12. Reimold and Koeberl, ref. 1, p. 122. Return to text.
  13. Norman, N. and Whitfield, G., Simplified geology of South Africa, Lesotho and Swaziland; in ref 6 inside front cover. Return to text.
  14. Oard, M.J., The remarkable African Planation Surface, J. Creation 25(1):111–122, 2011; creation.com/african-planation Return to text.

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Readers’ comments

King T.
Very interesting article. The mind just boggles at the size of such a crater.
Just on the pronunciation - the first "E" should sound like "EAR"(silent R) and with the V, the letters spoken as "FR-EAR".
So the whole word would be FR-EAR-DUH-FORT (last R is sounded "rrrh" ). Anyway, that's the best I can do.
Zach S.
Interesting; I just read an article saying an impact crater has been discovered off the coast of Scotland, actually in the ocean. Would this give validity to the instant global catastrophe model?
Tas Walker
Yes, impacts happen quickly and have large effects.
Keryn B.
My question is, what happened to the original (massive) asteroid? Were you saying that it was made of granite and buried itself in the ground? Or do they disintegrate on impact or erode?
Tas Walker
It is considered a small asteroid for such a large crater. It was not composed of granite but likely iron, although there is no evidence of its remains that has been reported. It would be assumed that the asteroid disintegrated or was eroded away.
Edgar A.
Most of the evidences I can read are the effects of the impact to the earth's crust, in my understanding. Unless I missed in the reading.
Questions:
Any evidence of the asteroid? like material properties that was identified, examined and verified?
Tas Walker
I am not aware that any evidence of the asteroid itself has been claimed.
Malcolm P.
Fascinating stuff! Makes me wonder if Velikovsky's theories (Worlds in Collision & Earth in Upheaval) may not have a great deal of validity. Many of his propositions have been demonstrated to be correct though no self respecting (read establishment respecting) scientist would ever acknowledge his precedence.
Tas Walker
Yes, Velikovsky was a trail blazer. He was able to get quite a few different ideas out there, ideas that have been built upon with further research and publication.
Eifion D.
“When it hit, the land surface there was 7–10 km higher.”

Is there an error here?
Tas Walker
No, that is not an error. It can be seen from Figure 4 that the rocks of the Witwatersrand Basin, Ventersdorp Lava, Ghaap Dolomite, and Pretoria Subgroup were already deposited when the impact occurred. These were originally nearly horizontal but were folded and deformed by the impact. It's from the thickness of those rocks that the thickness of the original land surface was estimated.
Willemien K.
Interesting. But where did the asteroid disappear? Surely if it was that big we would at least see some of its remains?
Tas Walker
Yes, that is a good point. I am not aware of any claim of identifying the asteroid.
Derek H.
Thank you for this informative article giving further evidence of catastrophic events shaping earth in the past. Especially your assessment of the time involved at and immediately after impact, brilliant. It is still quite difficult to get our minds round what happens in these events so studies like these are very helpful.
Keep up the good work of teaching creation by Almighty God.
Peter R.
The dating given in this article seems just as much speculation being stated as fact as what the evolutionists do. It's reads as if based on Biblical interpretation, and guesswork, rather than observation.
Tas Walker
The dating is based on observation and interpretation. The basis for the ordering of events is the field relationships of geological features. This is achieved by the various principles of stratigraphy, such as the law of superposition, law of original horizontality, law of cross-cutting relationships, and law of lateral continuity, etc. You can Google these principles. Mainstream geologists usually do a good job in sorting out the order of the rocks from their geological mapping, and publish their findings on geological maps. Creationist geologists would generally agree with this order.
Mainstream geologists then place these rocks within their dating scheme (which assumes the earth is 4.5 billion years old) from which they obtain the dates that are published. You will have to read other articles on creation.com that explain this in more detail.
Biblical geologists take the same information and fit it into the biblical framework.
Both of these approaches involve careful observation and speculation. The difference is that, if we accept the Bible as providing a true history of this planet, then we have a sound basis for making these timing deductions.
All this is explained together with the reasoning in the section that begins, "All this is said to have happened very early in the geological history of South Africa." There are other articles on creation.com that deal with this issue too.
Kobus G.
If the impact "occurred early in Noah’s Flood", then this must have caused what can only be described as a series of super tsunamis covering the globe. Has anybody modelled the waves that would have formed?
Glad it didn't topple the Ark...
Tas Walker
I'm not aware of any modelling of tsunamis from this.
Mike W.
Tas, wouldn’t a 10km asteroid impact cause problems with a young earth model? It is claimed by evolutionists that it would take large amounts of time for life to recover from the ejecta caused by such impacts..... Could the dome crater have been the result of the “fountains of the great deep” ie a volcano that started the Genesis flood? Your thoughts.....
Tas Walker
Some consideration of the effect of large impacts can be found in the article about Precambrian impacts. As the article above explains, geologists first thought that the structure was caused by volcanic magma welling up from within the earth, but they changed their interpretation based on other evidence (explained in the article) that pointed to an impact. Creationist geologists could develop scenarios based on either interpretation.
Wiley C.
I wonder if this was a comet (ice), rather than metallic rock (asteroid)?

I like using Gen 7:11 for apologetics. Deep sea vents were discovered in the 20th century. How would a "middle easterner" know about springs of the great deep?

Thanks for all you do!
Tas Walker
I suppose it could have been of ice but I've not read any reports that say that.
Dee M.
I've been studying and listening a lot to the Hydroplate Theory and their associated theories on how the Great Flood initiated. Seems entirely plausible that many of the impact craters that came down during the Great Flood period were actually very large chucks of earth ejected from various regions around the globe (when the crust erupted releasing the "fountains of the deep"), which then later fell back to earth as impactors.
Tas Walker
There are a number of big-picture speculative theories that are discussed among creation geologists. Hydroplate Theory is mentioned in a few articles on creation.com.
Floyd B.
This is interesting.
When was the ice age?
Tas Walker
It began about a year after this after the Flood ended, and lasted some 700 years. Search creation.com for "Ice Age".
Albie D.
We reside inside the crater rims and put an enlarged poster version of the article on display at our resort. The result is either very positive or very negative, anyway it makes people think! Thanks to Tas and Johan for a high quality article!
David J.
Continued good work by CMI. I encourage readers (if not already active) to access, from CMI, books to circulate to both Christians and non-Christians looking for resource material to strengthen their personal knowledge about the biblical age of the earth and much more. My favourites include Dr Sarfati''s the Genesis account and One Human family (forget author's name) Lita Costner joint project on "correct" bible (forget name) is a valuable perspective and enlightening given teaching in many churches today. I don't have a copy handy and, after reading material, I try to circulate. I think I heard, is it correct, that Dr Sarfat's Genesis Account is being taught in some US schools as a credit course?
Gregg J.
I have been immensely intrigued with this concept for the last 6 months, especially after the Chicxulub meteorite was mapped and computer modeling done on the impact. It was the size of Manhattan and produced a Tsunami 5000ft high.
The Chesapeake Bay was also a big one. The devastation, ejecta and surface breakup of the earth surely would qualify as "fountains of the deep opening up".
Take a look at another website- Is Genesis History dot com Geophysicists lectures on the Sedimentation of the earth. Excellent videos and amazing evidence of a young earth and a global flood.
I especially recommend one that is titled "130 Minutes to Explore the Causes of the Flood"
You will come away so certain of the Biblical flood.
Bradley B.
I find it really interesting that you guys put the impact during the flood, and as far as I can tell the explanation does make a lot of sense, but I don't remember any biblical reference to asteroids, is there anything you can say about that? God be with you!
Tas Walker
Just because something is not mentioned does not mean it did not happen. The Genesis account does not mention volcanoes either, but we can infer these occurred because we find their deposits in what are clearly Flood rocks.
Matt C.
I still believe in the "Waters Above". I also believe there were once twin planets where the asteroid belt is now. Stars and planets were for "signs and seasons". What better sign for the destruction God was about to send than the explosion of two planets? The moon is riddled with asteroid craters on one side from the initial impact of a multitude of asteroids, but the dark side has less craters that came as time passed. Thank you for pointing out that this impact came after flood sediments were present.
Tas Walker
There are a lot of ideas like these out there, and some are quite speculative. We always say that we should hold onto the Word of God tightly, but hold onto man's speculations loosely. Check our article Arguments we think creationists should not use.
Robert F.
You people are unbelievable! Your determination to put a “young earth” twist on every scientific topic, comes from misinterpreting the metaphoric truth of Genesis as being literal. You are trying to pound a square peg into a round hole.
Tas Walker
Yes, that is what we do. Uniformitarian geologists do the same thing. They are determined to put a long-age twist on every evidence, no matter how clearly it points to a young earth. I don't know where you get the idea that Genesis is metaphoric. Jesus and the Apostles who wrote the New Testament clearly accepted that Genesis was recording history, so we are simply being faithful to Christ.
Matthew C.
Thank you for the reply from Tas. I have had other creation scientists tell me not to hold onto the water canopy theory simply because we aren't smart enough to figure out how God was able to do it. But just because we can't figure out how the water was held up, doesn't justify not believing in the Second Day of creation. It must have been a truly difficult feat because it took God an entire day to do it. I have a fear that many are throwing out the entire second day of creation or at the very least, not explaining what they believe occured.
On the second day, the water on the earth was divided in two parts and separated by the sky which was between them. How can I throw that out? I had another creation scientist tell me that if the water was held up above the heaven, then the upper waters must have been beyond the stars. He was believing that there is only one heaven, but my bible say that God created the heavens and the earth. Heavens is plural. St John wrote in the Revelation that he was caught up to the third heaven, again showing that there is more than one heaven. So What is heaven? It appears to mean space. One heaven is what we call Inner Space where God placed the birds to fly. Another is where He placed the sun, moon, and stars. And the third is where he resides. All three are spaces, firmaments, expanses.
If you consider heaven as meaning space, you can also see earth as meaning matter. It gives new meaning to the first sentence of the bible. Time began when God created matter and space. A three dimensional universe caused by God. Time is a relation between events and the movement of matter through space. Time began when they were created and time will end when God destroys them.
Don't stop believing in the second day.
Tas Walker
You are correct when you say that just because we can'f figure out how it could have worked doesn't mean that it didn't happen. However, for an idea to be plausible we do need to be able to provide answers to some of these questions, and there are creation scientists who are working on other ideas that could possibly solve those problems for the canopy theory. Other creation scientists interpret the waters above as the waters that are held by clouds. Others (because Genesis says the sun, moon and stars were placed in the expanse which was under that waters—Genesis 1:14–19) suggest the waters were at the edge of our solar system, while others suggest they are at the edge of the universe. You have already described some of these ideas. Just because someone does not accept the idea of the water canopy does not mean they deny the events of the second day of creation. For a good summary of the water canopy theory see chapter 12 of the Creation Answers Book.

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