Image: Impact layer rock sample
This rock sample from New Zealand shows the layer formed during the end-Mesozoic extinction event. Over 200 extinction layer sites around the world have produced elevated levels of the metal iridium. Iridium is rare in the Earth’s crust but relatively common in meteorites.
- © Australian Museum
Sample labels (from top of sample to bottom):
- Recovery zone - Palaeogene rock: contains fossils of marine life, but not as many as before the end-Mesozoic event.
- Dead zone - Palaeogene rock: contains no fossils of marine life except for a small amount of plankton.
- Boundary zone - end-Mesozoic rock: contains high levels of iridium.
- Normal zone - Cretaceous rock: contains lots of fossils of lots of different types of marine life.