Marie Stopes (1880–1958) is best known as a birth control pioneer, but she was also a world-renowned coal geologist and palaeobotanist. This paper provides a historical account of her fieldwork on the Jurassic coast of Brora, NE Scotland. Accompanied by her undergraduate assistant, David Meredith Seares Watson (who was later a well-known vertebrate palaeontologist), Stopes visited this remote region amid a freak heatwave in March 1907. The aim of the trip was to locate Mesozoic permineralized peat deposits (coal balls) similar to those found in the Carboniferous rocks of northern England. Stopes controversially believed that if one understood the mode of origin of a geological phenomenon, it was possible to predict exactly where it would occur. It was this kind of ‘geoprophesy’ (as she called it) that had led her to explore Brora for coal balls. However, in this case, Stopes’s prophetic powers seem to have failed her and no coal balls were located. Nevertheless, it is a tribute to her flexibility and determination that she went on to find an important Middle Jurassic flora, which improved correlation between the Brora succession and the classic reference sections of the Yorkshire coast. In the course of this research, Stopes corresponded with several highly influential geologists. Of these, John Wesley Judd and Albert Charles Seward proved particularly useful, helping her to secure her first major grant from the Royal Society (both men were on the review board). That grant was to fund an 18-month expedition to Japan, and its purpose was also to search for Mesozoic coal balls.