Vallee-Poussin, CHARLES-LOUIS-JOSEPH-XAVIER DE LA, professor of geology and mineralogy at the Catholic University of Louvain (1863), doctor honoris causa of the same university (1876), foreign member of the Academie Royale de Belgique (1885), vice-president of the directing council of the geological map of Belgium (1903), b. at Namur in 1827; d. at Brussels, 1903. De la Vallee Poussin made his humanities at the College Notre-Dame-de-la-Paix, Namur, studied mathematics at Paris, and for ten years devoted himself to literature and philosophy. He attracted attention by his literary and scientific criticisms in various reviews. Appointed professor in 1863 on the recommendation of Omalius d’Halloy, he was the real creator of the teaching of geology and mineralogy at the University of Louvain, His scientific publications, scattered through numerous reviews from 1876 till 1903, placed him in the foremost ranks of Belgian geologists and crystallographers. Especially noteworthy were his memoirs on the microscopic study of the crystalline rocks of Belgium and French Ardennes, several in collaboration with A. F. Renard, particularly the first (1876), which was crowned by the Royal Academy of Belgium and has become a classic; his numerous notes on Belgian carboniferous limestone, which fix the true stratigraphical relations of its beds and destroy Dupont’s theory of lacunae; his researches concerning the formation of the Valley of the Meuse; and his popularizing articles, which rank him with the first promoters of physical geography; finally his share in the preparation of the official geological chart of Belgium.