Old geological maps are extremely important sources of information about the state of geological knowledge of a specific period. Using GIS techniques, the old geological data and concepts can be compared and analyzed together with modern ones. Thus, the aim of this work is to present some old Transylvanian geological maps from the second half of the nineteenth century, with special respect to their legend and topographic basis, as well as to discuss the georeferencing methods and results in order to incorporate them into a unified GIS database. The geological maps of this study are the followings: the geognostic map of the Habsburg Empire by Haidinger (Geognostische Uibersichts-Karte der Oesterreichischen Monarchie 1845); the geological map of Transylvania by Hauer et al.(General-Karte des Grossfürstenthums Siebenbürgen und der im Jahre 1861 mit dem Königreiche Ungarn vereinigten Theile 1863); the geological map of the Habsburg Empire by Hauer (Geologische Ü bersichts-Karte der Ö sterreichisch-Ungarischen Monarchie nach den Aufnahmen der k. k. geologischen Reichsanstalt 1867-1871); the geological map of the Seklerland by Herbich (A Székelyföld földtani térképe 1878a). These maps were compiled using as topographic basis the map sheets of the 1st and 2nd Military Survey of the Habsburg Empire (later Austro-Hungarian Monarchy).

ABSTRACT:One of the most most outstanding achievement of the Transylvanian geological mapping activity of the mid-nineteenth century, namely the overall geological map of Transylvania by Hauer (1861) represents an important part of our cartographic heritage. Therefore, the aim of this study is on the one hand, to offer a brief survey about the historical cartographic overview of the map with special respect to the geological mapping activity of Transylvania in the midnineteenth century. On the other hand, the paper summarizes the cartographic analysis which has been made in order to geo-reference the map in its initial projection and geodetic datum. The rectification has been performed in Global Mapper v16.1 using all the crossings of the grid lines, while the geometric accuracy of the map has been analysed with the MapAnalyst 1.3.23 software application. This analysis is necessary when the goal is to extract geological information from several geological maps from different periods in order to compare the old geological data with modern ones and to make possible the tracking of the evolution of geological knowledge in time.

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