Jules Desnoyers

Jules Pierre François Stanislaus Desnoyers (8 October 1800 – 1 September 1887) was a French geologist and archaeologist.

Life
Desnoyers was born at Nogent-le-Rotrou, in the department of Eure-et-Loir. Becoming interested in geology at an early age, he was one of the founders of the Geological Society of France in 1830. In 1834, he was appointed librarian of the Muséum National d'Histoire Naturelle in Paris. He was elected a Foreign Member of the Geological Society of London in 1864. Parts of his collection of rare books in the earth sciences was bought by the United States Geological Survey Library at an auction in 1885. He was the Secretary of the Historical Society since its founding.

Speleological activities
Desnoyers was a spelunker. His article on caves for the Dictionnaire universel d’histoire naturelle (1841-1849) of Charles Henry Dessalines d'Orbigny broke new ground, emphasizing the role of hydrological phenomena in limestone and gypsum caves. He explored the subterranean quarries of the Île-de-France. He was one of the first to study small mammals that lived in zones of karstic infill.

Works
His contributions to geological science comprise memoirs on the Jurassic, Cretaceous and Tertiary Strata of the Paris Basin and of Northern France, and other papers relating to the antiquity of man, and to the question of his co-existence with extinct mammalia. In 1829 he proposed the term Quaternary to cover those formations which were formed just anterior to the present, following an antiquated method of referring to geologic eras as "Primary," "Secondary," "Tertiary," and so on.

His separate books were Sur la Craie et sur les terrains tertiaires du Cotentin (1825) and Recherches géologiques et historiques sur les cavernes (1845).