Joseph Lucas joined the Geological Survey in 1867 and spent almost 9 years mapping in Yorkshire. Forced to resign in ignominious circumstances, for the rest of his life he earned his living advising on groundwater supplies. In 1874 he was the first to use the term hydrogeology in its modern context and defined this new subject in a series of papers in the 1870s. He drew the first British maps showing groundwater contours and described how to carry out a hydrogeological survey. For many years he lobbied for such a survey to be carried out over the whole country and for it to be used as a basis for water resource planning. He was an accomplished linguist, translating material from a variety of European languages, and wrote books on natural history and genealogy. He and his family lived at Tooting, in south London, where he is buried in the Churchyard of Saint Nicholas.