ancient continental mass in the Northern Hemisphere that included North America, Europe, and Asia (except peninsular India). Its existence was proposed by Alexander Du Toit, a South African geologist, in Our Wandering Continents (1937). This book was a reformulation of the continental drift theory advanced by the German meteorologist Alfred Wegener (Wegener, Alfred Lothar). Whereas Wegener had postulated a single supercontinent, Pangea, Du Toit theorized that there were two such great landmasses: Laurasia in the north and Gondwana in the south, separated by an oceanic area called Tethys (Tethys Sea). Laurasia is thought to have fragmented into the present continents of North America, Europe, and Asia some 66 million to 30 million years ago, an interval that spans the end of the Cretaceous (Cretaceous Period) Period and the first part of the Paleogene Period.