BERTRAND, MARCEL-ALEXANDRE

born July 2, 1847, Paris, Fr. died Feb. 13, 1907, Paris French geologist who introduced the theory that certain mountains, in particular the Alps, were formed by folding of the Earth's crust. In 1886, two years after he first proposed his theory of mountain building, Bertrand became instructor at the cole Nationale Suprieure des Mines. During summers he did fieldwork for the French Geological Survey and also attempted to determine how the European mountain chains were created. In 1887 he developed a wave concept of mountain building, postulating successive periods of massive folding of the Earth's crust during which the Caledonian, Hercynian, and Alpine orogenies gradually built up the European system of mountains. Later he introduced a fourth period, the Huronian orogeny, of the Precambrian time. His work and publications established modern tectonic research, especially in the Alps, but his publications were few and his ideas were spread chiefly by his students. He was elected to the Academy of Sciences in 1896.