In 1836 a multi-year survey was established to collect information on the geology and natural history of New York. For purposes of the survey, the state was divided into four districts, and Hall became assistant geologist for Ebenezer Emmons, chief of the Second District. Hall's initial assignment was to study iron deposits in the Adirondack Mountains. The following year the survey was reorganized: Hall was put in charge of the Fourth District, in western New York. Other notable geologists working on the survey included Lardner Vanuxem and Timothy Conrad. Working together, the survey staff developed a stratigraphy for New York and set a precedent for naming stratigraphic divisions based on local geography.