Eugene Shoemaker and the Impact Paradigm in Earth and Planetary Science

Abstract

A view of earth from space portrays a tranquil oasis — clouds drift peacefully over blue oceans as the seasons come and go, while underneath tectonic plates spread at mid-ocean ridges and descend under gradually rising mountain ranges. Intermittent earthquakes and volcanic eruptions merely interrupt the perpetual rhythm. This contrasts sharply with the otherwise violent solar system, where the faces of planets and moons bear the scars of meteorite impacts, or consist of frozen wastelands, sulphuric volcanoes or turbulent gaseous eddies. The apparently uniform cyclic nature of sedimentation, mountain building and erosion led James Hutton (1726–1797) and Charles Lyell (1797–1875), the founding fathers of geology, to establish the paradigm of uniformitarianism, which replaces the catastrophism inherent in biblical creation.