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Rodger Hart explains the structural features of the Vredefort
dome to the group with Tim Raub and Antonin Bouchez acting as map-holders.
The Vredefort impact occurred 2.0 billion years ago and the structure is the largest and
oldest impact crater on Earth. The map shows dark pink granulite and pink
granite surrounded by orange and brown overturned sediment layers.
The granite plug in the center of the impact is about 50 km across.
The group is actually sitting on granite with the overturned
sediment layers visible to the north on the skyline behind Tim and Antonin.
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| Picture by Liz Johnson |
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The group listen to Rodger Hart and Joe discuss the Vredefort impact. |
| Picture by Magali Billen |
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At the same location as 01_liz_vredeforttalk.jpg. The granite in
the center of the Vredefort Dome (the light-colored rock beneath Magali's feet) was
shocked during the impact, and locally melted to form glass. This is called
pseudotachylite.
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| Picture by Liz Johnson |
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Jenny Ives sitting on the bank of the Vaal River at the location
where we looked at shatter cones in quartzite. "Vaal" means "dirty" in Africaans. We
could see a lot of debris high above this spot along the river, evidence of the major
flooding which happened the previous winter. |
| Picture by Liz Johnson |
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Pseudotachylite at a quarry in the impact crater. Large boulders appear to be suspended in
the black shock-melted glass. At the corner it is possible to get a more 3-D view of the melt
region. |
| Picture by Magali Billen |
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We visited (and sampled) banded iron formations (BIFs) in the
granulite-facies rocks near ground zero of the impact. The BIFs were in the middle of a
very large field full of termite mounds. |
| Picture by Liz Johnson |
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The group at ground zero - the center of the Vredefort Crater. |
| Picture by Laura Croal |
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Sunset over the eroded crater rim. |
| Picture by Kristin Cook |
Day 2