Geothermal gradients from published temperature/depth measurements in drill holes generally deeper than 600 m are used to construct a temperature gradient map of the conterminuous United States. The broadly contoured map displays 284 temperature gradients that are applicable to a depth of 2 km. In terms of the number of contoured areas and the fraction of data points having a value not within a contour interval (outliers), the temperature gradient data and associated deep heat flow data have similar measures of contourability. Areally, most of the United States is contoured from 15o to 35oC/km. The E USA is generally cooler (average 25oC/km) than the W USA (average 34oC/km), in accordance with broad heat flow trends. -from Authors
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Geothermal gradients in the conterminous United States.