Geothermics is the study of heat generated in Earth's interior and its manifestation at the surface. The NOAA National Centers for Environmental Information has a variety of publications and data sets which provide information on the location, magnitude, and potential uses of geothermal resources. The publication, "Thermal Springs List for the United States" (1981) is a compilation of 1,700 thermal springs locations in 23 states. The list gives the geographic locations of thermal springs by state, and is sorted by degrees of latitude and longitude within the state. It contains the name of each spring (where available), maximum surface temperature (in both degrees Fahrenheit and degrees Celsius), name of corresponding USGS 1:2,500,000-scale (AMS) map, largest scale USGS topographic map coverage available (either 7.5 or 15-min. quadrangle), and cross-references. Thermal springs listed include natural surface hydrothermal features (springs, pools, mud pots, mud volcanoes, geysers, fumaroles, and steam vents) at temperatures of 20 degrees Celsius (68 degrees Fahrenheit) or higher. They do not include wells or mines, except at sites where they supplement or replace natural vents that have been active recently or at sites where orifices are indistinguishable as natural or artificial. The thermal springs data from this publication are also available on-line."Geothermal Gradient Map of the United States" (1982) shows 1,700 wells, with accompanying heat flow and conductivity data. This map was produced in cooperation with Los Alamos National Laboratory. Thermal aspect data (1991) from the Decade of North American Geology project, are available on diskette. These data were compiled by Dr. David Blackwell of Southern Methodist University. Global heat flow data (1993) were compiled by Dr. Henry Pollack of the University of Michigan. Data were collected through the World Heat Flow Committee of the International Council of Scientific Unions. These are available on-line.