Charles Lyell published a geologic map of the Lake Superior region in 1845 as an appendix to his epochal Travels in North America. One of the published sources Lyell used to compile this map was an 1829 report by H.W. Bayfield, who as a surveyor for the Royal Navy spent the years 1823 to 1825 circumnavigating the lake. Bayfield's report, in turn, included the geologic observations of two other travelers on the lake: H.R. Schoolcraft and J.J. Bigsby, both of whom, like Bayfield, had taken part in some of the earliest government-sponsored explorations in the region. Although Schoolcraft had received some formal training in the natural sciences, Bigsby and Bayfield, like many other naturalists of the time, gained their knowledge of geology while pursuing their primary professional duties. Nonetheless, they were exceptionally good observers of geologic phenomena. Their efforts produced a geologic framework for the Lake Superior region, which is even today compatible with modern interpretations. At the end of the 19th century, though, their contributions had been all but forgotten, a result of a revolutionary change in the study of geology from a more informal and descriptive pursuit to a professionally oriented and theoretical science with its own organizational structure.
Pre-Cambrian rocks of the Lake Superior region, a review of newly discovered geologic features, with a revised geologic map