At intervals in the Earth's history there have been mass extinctions, when the number of species of animals and plants was drastically reduced in a time that was geologically short. There has been little agreement about their cause, with suggestions ranging from catastrophes to the cumulative effect of changes in factors such as temperature. It is accepted that abrupt and violent processes, such as meteorite impacts and great volcanic eruptions, do occur from time to time, but it is also being appreciated that the environment, particularly the climate, is less stable than had been thought, so that the cumulative effect of comparatively small, steady changes may have large and abrupt consequences. Therefore, an appreciation of the environmental effects of impacts and volcanism will increase our understanding of the processes at work in the world we inhabit today, as well as possibly accounting for some extinctions in the past.
This chapter examines some of the evidence that the K/T (end-of-Cretaceous) extinction was due to the impact of an extraterrestrial body that produced the Chicxulub structure, and looks briefly at the competing theory that volcanism was responsible.
Introduction
Throughout the Earth's history the forms of living organisms have changed, and the ever-changing mix of organisms has permitted the Phanerozoic timescale to be constructed (Section 15.11).
Review the options below to login to check your access.
Log in with your Cambridge Aspire website account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.