Geothermal gradient map of Colorado. 1 plate (1:1,000,000). This 1981 map shows contoured geothermal gradients in degrees Celsius per kilometer (°C/km) based on reported bottom-hole temperatures taken from 12,000 oil and gas wells. Contours range from 20° to 45°C/km. Also shown on the map are shaded areas of volcanic and Precambrian rocks. Digital PDF download. MS-20D
This map was updated by Map Series MS-51 in 2010, which has three plates, the first of which is entitled “Interpretative Geothermal Gradient Map of Colorado”. A similar map product published in 2008 is MS-45 “Interpretative Geothermal Heat Flow of Colorado”.