This project will produce a scientific biography of Alfred Wegener, the German polar scientist and meteorologist best known as the originator of the theory of continental drift. The project will use Wegener's life and work to explain the evolution of earth sciences in the first half of the twentieth century. The project will endeavor to show that the theory of continental drift was not a renegade idea proposed by an outsider, as some might believe, but instead was a mainstream hypothesis proposed by a mainstream scientist and based on widely- used data sets. Further, the PI will show that the debate about `Wegener's theory` is best seen as a constructive, communal effort by earth scientists to find how best to organize a vast fund of empirical data. This is an idea Wegener himself would have endorsed, since he viewed science as a social enterprise evolving on a time scale much longer than an individual scientific career.