The first naturalistic drawings of geologic phenomena, particularly rock formations, are assumed by historians to have occurred early in the 19th century, when geology matured as a science. No less than three centuries earlier, however, the Netherlandish master, Jan Van Eyck, drew exposures of natural rock whose features are so remarkably accurate as to permit modern-day geologic analysis of their lithology, fossil content, sedimentary structures, and depositional environment. Van Eyck clearly studied, drew, and painted a specific outcrop "in the field," long before such practice had become common in art or science. As the first modern geologic "observer," Van Eyck greatly extended an existing tradition of naturalism with regard to organic phenomena (esp. plants, insects, human figures) fully into the realm of inorganic reality. In this, he far surpassed other scholar-artists, such as Leonardo da Vinci, who have been credited with similar achievements. Van Eyck's achievement proved exceptional. It was matched neither by later artists, scientists, or illustrators until the late 18th-early 19th century, when conventions in travel literature and landscape inspired new attention to the drawing of rock materials. The reasons for this historical gap have everything to do with the limitations of observation in early geological study, which show important parallels to those in art.