The events that caused the extinctions at the end of the Cretaceous Period remain contraversial. Recently, the debate has centered around the Alvarez Model, which theorizes that the extinctions were caused by the impact of a large meteorite. The literature is reviewed and a non-catastrophic event of terrestrial origin is presented to explain the extinctions. A list of discussion topics wih references is provided as an aid to devoloping a college-level seminar on the controversy.