Geological research in North America developed from a few isolated inquiries in the eighteenth century to a mature descriptive science by 1818. In 1771, the study of earth science in America was limited to a few observations on diverse subjects. Systematic investigation and classification of rocks, minerals, and fossils was unknown. Several European and American scientists recognized the need for a standardized nomenclature and unambiguous identification methods in the earth sciences. Thus by 1818, through the efforts of Werner and Maclure in field geology, Cuvier and Brongniart in paleontology, and Cleaveland in mineralogy, systematic classification of geological materials had been introduced to America. These contributions established the science of geology in the United States and enabled the next generation of earth scientists to describe fully the natural history and resources of North America.