Yol. 62.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lv 



during the middle of his ten eruption -periods. It was the 

 foundations that Bichthofen accepted from his teachers, and not his 

 methods that were at fault. But his speculations will always be 

 of interest, from his early appreciation of the facts subsequently 

 explained by magmatic differentiation : and from his attractive 

 suggestion of fissure-eruptions, by which he sought to account for 

 the occurrence of lavas on a scale transcending all European 

 experience. 



His most famous contribution to tectonic geology, though not 

 confirmed by more detailed later surveys, was his explanation that 

 the dolomite ' Colossi/ as he called them, of the Tyrol, were coral- 

 atolls built in a Triassic sea ; that the associated St. Cassian Beds 

 were the contemporary deep-sea deposits, on the ocean-floor between 

 the atolls ; and that the Eaibl Beds were mainly coral-sands on 

 the shores of the atolls, or fragmental limestones formed between 

 the reefs in the last stage of coral-formation. This hypothesis 

 was announced in 1860 in his ' Geognostische Beschreibung von 

 Predazzo,' and reasserted in 1874, in his paper on the Mendola 

 Dolomite, and then supported by arguments derived from his study 

 of living reefs in Malaysia. 



Richthofen's most successful addition to geology was his solution 

 of the vexed question of the origin of loess, in a series of papers 

 between 1872 and 1882, and mainly in the first volume of his 

 ' China' in 1877. From the study of the loess in Eastern China, 

 he concluded that it must have been a subaerial steppe-formation. 

 This inference from the lithological characters of the deposit he 

 supported by study of its actual formation in progress in the steppes 

 of Mongolia. The occurrence of loess of identical composition, in 

 Germany and Central Europe, led him to the opinion that steppe- 

 conditions must once have prevailed there; and this conclusion, 

 based on the evidence of physical geology, was fully confirmed when 

 the palaeontological work of Kehring showed that the bones in the 

 German loess belonged to a steppe-fauna. [J. W. G.] 



Gilles Joseph Gustave Dew alette, who was elected a Foreign 

 Correspondent in 1871 and a Foreign Member in 1880, was 

 born at Stavelot in Belgium on the 2nd of December, 1826. 

 He graduated as Doctor of Medicine and of Sciences in the 

 University of Liege, and in 1857 succeeded Dumont in the Chair 

 of Geology. In 1865 he was appointed Ordinary Professor of 

 Mineralogy, Geology, and Palaeontology, and only retired a few 



