5 Yet 60 million years ago in the late Palaeocene there was another huge amount of
volcanic activity and global warming but}Io mass extinction．Some animals did disappear but things returned to normal within ten thousands of years，“The most recent ones hardly have an effect at all?！?Wignall says．He ignored the extinction which wiped out the dinosaurs at the end of the Cretaceous，。65 million years ago，because many scientists believe it was primarily caused by the impact of an asteroid． ’
6 Wignall thinks that older volcanoes had more killing power because more recent life
forms were better adapted to dealing with increased levels of C02 ．Ocean chemistry may also have played a role．As the supercontinents broke up and exposed more coastline there may have been more weathering of silica rocks．This would have encouraged the growth of phytoplankton in the oceans。increasing me amount of C02 absorbed from the atmosphere．
7 Vincent Courtillot director of the Paris Geophysical Institute in France，says that
Wignall’s idea is provocative．But he says it is incredibly hard to do these sorts of calculations．He points out that the killing power of volcanic eruptions depends on how long they lasted．And it is impossible to tell whether the huge blasts lasted for thousands or millions of years。
8 Courtillot also adds t11at it is difficult to estimate how much 1ava prehistoric volcanoes produced , and that 1ava volume may not necessarily correspond to carbon dioxide or sulphur dioxide emissions．
練習(xí)：
1．Paragraph 2
2．Paragraph 3
3．Paragraph 4
4．Paragraph 5
A Killing Power of Ancient Volcanic Eruptions
B Association of Mass Extinctions with Volcanic Eruptions
C Calculation of the Killing Power of Older Eruptions
D A Mass Extinction
E V_0lcanic Eruptions That Caused no Mass Extinction
F Accounting for the Killing Power of Older Eruptions
5．Older eruptions were more devastating
6．The Permian extinction is used to illustrate
7．The cause of the extinction of dinosaurs
8．Courtillot rejects
A than more recent ones
B the killing efficiency for older eruptions
C has remained controversial
D Wignall’s calculations as acceptable
E has been known to us all
F his ideas
volcanic activity and global warming but}Io mass extinction．Some animals did disappear but things returned to normal within ten thousands of years，“The most recent ones hardly have an effect at all?！?Wignall says．He ignored the extinction which wiped out the dinosaurs at the end of the Cretaceous，。65 million years ago，because many scientists believe it was primarily caused by the impact of an asteroid． ’
6 Wignall thinks that older volcanoes had more killing power because more recent life
forms were better adapted to dealing with increased levels of C02 ．Ocean chemistry may also have played a role．As the supercontinents broke up and exposed more coastline there may have been more weathering of silica rocks．This would have encouraged the growth of phytoplankton in the oceans。increasing me amount of C02 absorbed from the atmosphere．
7 Vincent Courtillot director of the Paris Geophysical Institute in France，says that
Wignall’s idea is provocative．But he says it is incredibly hard to do these sorts of calculations．He points out that the killing power of volcanic eruptions depends on how long they lasted．And it is impossible to tell whether the huge blasts lasted for thousands or millions of years。
8 Courtillot also adds t11at it is difficult to estimate how much 1ava prehistoric volcanoes produced , and that 1ava volume may not necessarily correspond to carbon dioxide or sulphur dioxide emissions．
練習(xí)：
1．Paragraph 2
2．Paragraph 3
3．Paragraph 4
4．Paragraph 5
A Killing Power of Ancient Volcanic Eruptions
B Association of Mass Extinctions with Volcanic Eruptions
C Calculation of the Killing Power of Older Eruptions
D A Mass Extinction
E V_0lcanic Eruptions That Caused no Mass Extinction
F Accounting for the Killing Power of Older Eruptions
5．Older eruptions were more devastating
6．The Permian extinction is used to illustrate
7．The cause of the extinction of dinosaurs
8．Courtillot rejects
A than more recent ones
B the killing efficiency for older eruptions
C has remained controversial
D Wignall’s calculations as acceptable
E has been known to us all
F his ideas