In early years as
ingénieur des mines, Delesse investigated and described various new
minerals; he proceeded afterward to the study of
rocks, devising new methods for their determination, and giving particular descriptions of
melaphyre,
arkose,
porphyry,
syenite, and others. The
igneous rocks of the
Vosges, and those of the
Alps,
Corsica, etc., and the subject of
metamorphism occupied his attention. He also prepared in 1858 geological and hydrological maps of Paris, with reference to the underground water, similar maps of the
départements of the
Seine and
Seine-et-Marne, and an agronomic map of the Seine-et-Marne (1880), in which he showed the relation that exists between the physical and chemical characters of the
soil and the geological structure. The annual
Revue des progrès de géologie of Delesse, undertaken with the assistance (1860–1865) of
Auguste Laugel and afterwards (1865–1878) of
Albert de Lapparent, was carried on from 1860 to 1880. His observations on the
lithology of the deposits accumulated beneath the sea were of special interest and importance. His separate publications were: ''Recherches sur l'origine des roches
(Paris, 1865); Étude sur le métamorphisme des roches
(1869), Lithologie des mers de France et des mers principales du globe'' (2 vols. and atlas, 1871). == Honors ==