IDENTIFYING COLORS ON EARLY GEOLOGICAL MAPS: A COMPARISON OF METHODOLOGIES

摘要

As my initial project employing a photospectrometer to study geological map color, I have selected the mid-19th-century Cartes geologiques departmentales de France. Conceived by French geologist Andre Brochant de Villiers in 1820, these maps formed the second phase of his plan to map the geology of France. The first phase, the Carte geologique generale de France published in 1840, received praise as the first official geological map of France. The second phase, geological maps of the administrative departements of France, was delegated to local authorities, who were instructed to organize and pay for the map of their departement. The varying scales, symbolization, authors, formats and irregular sheet lines of the resulting maps hindered their utility. Never completed, the series gave way in 1868 to the Carte geologique detaillee de France, a model of uniformity. The design variety of the Cartes geologiques departmentales contributed to the emerging official geological map image of France during the 19th century. Color data collected by the chosen method will reveal design relationships among these maps. Of course color is only one design variable, and the study will also consider the use of patterns in combination with area colors. Equally important, the graphic characteristics of geological symbols will be linked to the geological content being depicted. Investigating the influence of developing geological theories and knowledge on color and pattern choices will invest this study of map design with meaning for the history of science, both geological and cartographic.