French geologist and paleontologist known for his contributions to the theory of geosynclines (geosyncline) (trenches that accumulate thousands of metres of sediment and later become crumpled and uplifted into mountain chains).

After receiving his Ph.D. from the University of Strasbourg (1884) and spending three years in postgraduate research, Haug moved to Paris, where he joined the geology faculty of the Sorbonne in 1897. In his research, Haug surmised from the position of the Alps that geosynclines form between stable continental platforms. Through his analysis of sedimentary facies, he established that geosynclinal sediments accumulate in both deep and shallow troughs. He also showed that geosynclinal subsidence accompanies marine regressions on the continental platform and that geosynclinal uplift accompanies marine transgressions on the continental platform. His Traité de Geologie, 2 vol. (1907–11; “Treatise of Geology”), contains his ideas about geosynclines.