In 1882 a young natural scientist, Thorvaldur Thoroddsen (1855-1921), set out to explore the country. He travelled around most of it between 1882 and 1898. His main project was however to investigate the geology of the country with a special focus on volcanic remains. He soon realized that there were errors in Bjorn Gunnlaugsson’s map, especially in the highlands of the interior. But geodetic surveys didn’t fit into Thoroddsen’s research and was always just a side issue. He was the first person who explored and mapped the wasteland west of Vatnajokull, a place that Bjorn Gunnlaugsson never visited and was led astray by stories of uninformed people. Nobody had passed through large parts of this region, this being the country’s last frontier to be explored. In addition Thorvaldur Thoroddsen made several minor changes and adjustments, especially in the highlands but otherwise it is totally based on Bjorn Gunnlaugsson’s map.
In 1900 Thorvaldur Thoroddsen published a new complete map of the country in two sheets: Uppdráttur Íslands (Kort over Island). In that map he compiles his adjustments and appendixes and adapts them to Gunnlaugsson’s map. A year later his Geological Map of Iceland was published. The map is in fact the same as the map of the year before, with geological colors added. In 1906 a revised variation of the map was published in Germany in reduced scale: Geologische Karte von Island. Attached is a description of the country in German which has the main conclusions of Thoroddsen’s research.