The argument for extinction by volcanoes

1
The argument for extinction by volcanoes

• The Earth's crust is made up of layers of rock.
• The deeper the layer, the longer ago the layer
  was created.
• Fossils of dinosaurs are only found in layers of
  rock formed between about 250 and 65 million
  years ago.

2

• Dinosaur fossils are not found after about 65
  million years ago.
• Dinosaur fossils start to gradually become rarer
  in rocks from about 72 million years ago.
• Then they become increasingly rare during the
  final 300 thousand years before the dinosaurs
  became extinct.

3

• Fossils show that during that time, mammals were
  rapidly evolving

4

• In North India there is a region of volcanic rock
  2000 metres deep covering about half a million
  square kilometres.
• When it was originally formed, it would have been
  about three times larger.
• This region is now known as the Deccan Traps.

5

• The rock leaked out as magma from deep within the
  Earth between about 68 and 60 million years ago.
• Most of rock in the Deccan Traps leaked out about
  66 million years ago.
• This period may have lasted less than 30,000
  years.

6

• The amount of magma produced at this time would
  have been about 1 million times greater than the
  eruption that destroyed Pompeii.

7

• ? The dinosaurs start to become extinct about the
  same time the Deccan Traps started to form.
• ? The final extinction of the dinosaurs happened
  very close to the time the Deccan Traps event was
  most active.
• ? Even far, far smaller volcanoes can cause
  short-term climate change.
• ? The Deccan Traps would have caused major
  climate change.
• ? These changes would have been greatest during
  the time the dinosaurs became extinct.
• ? Therefore the dinosaurs could not cope with
  these changes and became extinct.