Heinrich Lotz, German geologist, was a colleague of F.W. Erich Kaiser* at the Prussian Geological Institute in Berlin during the first few years of the twentieth century. His first substantial scientific paper dealt with "Die fauna der Massenkalks der Lindener Mark bei Giessen" (Schriften der Gesellschaft zur Befoerderung der gesammten Naturwissenschaften zu Marburg, 1900). In 1903 he was appointed by the German Colonial Office to the newly created post of Government Geologist of German South West Africa (now Namibia). He joined the other government geologist of the territory, F.W. Voit* in February 1904 and remained in his post until the middle of 1906. During most of this period he served also in the Schutztruppe (colonial forces). As the war between the Germans and the Hereros was in progress geological research was somewhat limited and he concentrated on the search for groundwater. In 1906 a branch of the Mining Commission was opened in Luderitz and Lotz was seconded there as geologist for the southern region of the territory (south of the Tropic of Capricorn). He was succeeded in that position in 1906 by P. Range*. That same year he published "Vorlaeufige Mitteilungen zur Geologie DSWA" (Preliminary account of the geology of German SWA) in the Zeitschrift der Deutschen Geologischen Gesellschaft, summarising geological research in the territory.
In 1908 Lotz joined the newly founded Deutsche Diamantengesellschaft in German South West Africa and eventually became its director. His geological research during the first few years with the company was described in several publications. One of these, "Ueber die Diamantablagerungen bei Luderitzbucht" (On the diamond beds near Luderitz), in the Zeitschrift der Deutschen Geologischen Gesellschaft (1909) provided a good summary of the geology of the diamond deposits. Others dealt with German diamond production (1912), and the position with regard to tin mining in the Windhoek district (1912). A comprehensive geological and geomorphological study of the diamond-bearing strata along the Namibian coast from the Orange River to Walfish Bay was published as "Vergleichende Studien ueber die SWA Kueste und ihre Diamantlagerstaetten" in Beitraege der Geologischen Erforschungen Deutsches Schutzgebiet (1913, Vol. 5, pp. 1-57). This volume also contained a contribution on the tertiary fossils of the Bogenfels area, by J. Bohm and W. Weissermel. The two papers were subsequently published together in a separate volume, under the title Geologische und palaeontologische Beitraege zur Kenntnis der Luederitzbuchter Diamantablagerungen (Berlin, 1913) under the names of Lotz, Bohm and Weissermel. Lotz also collaborated with P. Sprigade on the compilation of a map of the Sperrgebiet (1910). In 1913 he furthermore wrote a paper on geological research and mapping in South Africa (Zeitschrift fuer Praktische Geologie, 1913). Meanwhile his petrographic collection had been studied and published upon by F.W. Erich Kaiser. In 1910 he presented a series of invertebrate fossils that he had collected from the Devonian beds of the Rhine province, Germany, to the South African Museum. These were considered useful for comparison with the Bokkeveld fossils of the Cape Province.
Lotz's position with the Deutsche Diamantengesellschaft enabled him to employ Ernst Reuning* and later P.F.W. Beetz* to undertake geological investigations in the diamond area. In 1914 he also invited Kaiser, then professor of geology at Giessen, to Namibia to continue his studies in the field. Lotz was awarded a doctoral degree (PhD) by the University of Marburg at some time before or in 1910, and later became professor of geology. His inaugural dissertation, Die werwitterung einiger gesteinbildender mineralien unter dem einfluss von schwefliger saeure..., was published in Giessen in 1912. He was a member of the Royal Society of South Africa from shortly after its formation in 1908. In 1910 he became a member also of the Geological Society of South Africa. He left German South West Africa when World War I (1914-1918) broke out. At the end of the war, during 1918-1919, he applied to the South African government (which then administered South West Africa) to be allowed to return to the territory from Brazil. However, he does not appear to have returned to southern Africa and to have settled in Charlottenburg, Berlin. During the nineteen-twenties and -thirties he published a few more papers on mining in the German colonies, as well as an obituary of Kaiser in the Geologische Rundschau (1937). He was still living in Berlin in 1939.