Maps as pictures or diagrams: The early development of geological maps
Published:September 01, 2013
By means of numerous examples, this paper traces the early history of “geomaps” from the Renaissance to the early decades of the nineteenth century, considering in general terms the purposes for which the maps were compiled or the interests of the mapmakers. It is shown that a distinct change of style occurred approximately in the period from ca. A.D. 1760 to 1770, when maps changed from being pictorial (in various different ways) to diagrammatic. Following some early Italian work, the initial development of geomapping occurred particularly in the German-speaking parts of Central Europe and was chiefly associated with the work of Georg-Christian Füchsel and especially Abraham Gottlob Werner, along with his colleagues and former students. Such work was undertaken for economic reasons and was largely divorced from Werner's Neptunist doctrines. These maps showed the areal distributions of rocks of different types, and some showed the locations of mines and economically important minerals. By 1784, the whole of France was systematically mapped, but for the most part only showing the locations of economically important materials. These French and German maps did not convey any sense of time and were “positivistic” in character. In Britain, some Wernerian-style mapping was done, but this was overshadowed by the “biostratigraphical” mapping of William Smith, which started from economic concerns but eventually developed into an “end in itself” as he sought to produce a map for the whole of England and Wales and parts of Scotland. Smith's “pupil” John Farey produced maps of Derbyshire of extraordinary accuracy, as early as the first decade of the nineteenth century. The work of Alexandre Brongniart and Georges Cuvier focused on the Paris Basin and was (like Smith's work) based on the use of fossils, but it also showed an interest in the “conditions of existence” that obtained when the strata were deposited. Their work has been described and accepted as “geohistorical” and “properly geological,” whereas the earlier Wernerian maps were lithological in character, and initially the time dimension only appeared in them (to a small extent) with the work of Leopold von Buch. Attention is given to the question of the differences (if any) between geognostic and geological maps, and it is suggested that the conceptual differences were not fundamental. The category of “protogeological map” has been suggested, but its referent is not crystal clear. What is seen in the field is different from what appears in geological maps, which are forms of diagrams and need to be interpreted before use. Suggestions are made as to why geomaps appeared as and when they did. The role of the Industrial Revolution in leading to their production and development appears to be fundamental. Maps of special interest reproduced here are an anonymous one of Hel(i)goland, which is the first known to the author that delineates the boundaries between named lithological units; Georg-Christian Füchsel's remarkable map of Thuringia, here first published with color added; the strange and rather little-known colored manuscript map of Saxony by Christian Lommer; Werner's unpublished manuscript geognostic map of Saxony (1811); and John Farey's outstanding map of a part of Derbyshire. Various other little-known maps are also reproduced, as well as the “popular” ones of Johann Friedrich Wilhelm von Charpentier, William Smith, and Brongniart and Cuvier.