The discovery of iridium anomalies in three Cretaceous-Tertiary sections by the Alvarez team in 1980 prompted them to hypothesize an asteroid impact to explain these unusual concentrations. In the following years further evidence provided more support for their hypothesis, but a small minority of scientists are still unconvinced. Since the earth sciences were confronted with the impact hypothesis heated debates about mass extinctions, gradual or extraterrestrial causes, Lyellian uniformitarianism, evolution, and catastrophism got under way. Creationists have taken up this topic reluctantly, perhaps well aware that too much catastrophism may disturb cherished Flood models as well. Nevertheless, impact events did occur and should have their appropriate place in every earth model.
