DEVELOPMENT OF COLOR SIGNS AND PROJECTIONS OF THE HUNGARIAN ARCHIVE GEOLOGICAL MAPS

This paper summarizes the early geological maps about Hungary with special respect to their color codes, surface symbol systems and map projections. The process from the ad hoc color usage of the earliest maps, through the influence of the color system proposed by the Bologna Geological Congress of 1881 to the symbol system of the modern maps is shown. Analysing the coordinate grids of these map products, the older ones can be rectified in equidistant conic or Cassini projections while the ones of Bockh and Koch and Loczy et al. can be interpreted as both conic and Budapest-centered Stereographic projected. The ambiguity is because of the relatively low scale of the maps, enabling projection errors of several hundred meters without practical consequences.