This computation involved: Digitizing and processing of the Food and Agriculture Organization (FAO) Soil Map of the World deployed on Earth Resources Observation and Science (EROS). The original source maps are the Soil Map of the World, which was produced by the Food and Agriculture Organization (FAO) of the United Nations Educational, Scientific, and Cultural Organization (UNESCO) in 10 volumes between 1970 and 1978. It provides the most detailed, globally consistent soil data. The Earth Sciences and Resource Institute (ESRI) digitized the data under contract to the United Nations Environment Program (UNEP) and the FAO in 1984. The EROS Data Center constructed the data sets that were later used to derive the global array of average slope. The Center for Earth Resources Observation and Science (EROS) is a data management, systems development, and research field center for the U.S. Geological Survey's (USGS) Geography Discipline.