Uniformitarianism and the response of Earth scientists to the theory of impact crises.

The doctrine of uniformitarianism strongly influences the way Earth scientists view the evolution of this planet, through a tradition which uses the modern world as a model for the past, assumes gradualistic changes, and shuns catastrophic explanations. However, internally consistent evidence now supports a temporal correlation of a large-body impact with the mass extinction at the Cretaceous-Tertiary boundary. The past rate of large impacts on the Earth is in good agreement with the rate predicted from observations of orbiting objects.