Some of the earliest applications of the principles of geology to the solution of hydrologic problems were made by William Smith, who used his knowledge of strata succession to locate groundwater resources to feed the summit levels of canals and supply individual houses and towns. The industrial revolution led to a huge demand for water resources to supply new towns and cities. Nottingham, Liverpool, Sunderland and parts of London all relied on groundwater. By the middle of the nineteenth century James Clutterbuck had already recognized that groundwater was a finite resource and that if abstraction was more rapid than replenishment by rain, water levels would decline and quality would be affected by saline intrusion. In 1851 Prestwich produced the first British geological map that included groundwater information.