As a stratigraphical geologist he rendered much assistance on the Geological Survey of France, but in the course of time he gave his special attention to the study of volcanic phenomena and earthquakes, to minerals and rocks; and he was the first to introduce modern petrographical methods into France.
No assemblage of stratified rocks has received such careful and detailed examination as the Carboniferous system; consequently our knowledge of the stratigraphical sequence in isolated local areas, where the coals have been exploited, is very full.
In subdividing the strata of the Carboniferous system and correlating the major divisions in different areas, just as in other great systems, use has to be made of the fossil contents of the rocks; stratigraphical units, based on lithology, are useless for this purpose.
Their true stratigraphical position has not yet been ascertained, and it may appear that more than one group of rocks is included in the series.
Descriptions of the fossils, with some notes on stratigraphical questions, will be found in several of the volumes of the Palaeontologia Indica, published by the Geological Survey of India, Calcutta.