An oil and gas exploration well, located near Jesup in Wayne County, Georgia (lat. 31/sup 0/32' N, long. 81/sup 0/43' W), was deepened and used for geothermal temperature-gradient measurements. The well was drilled from 4,009 to 4,341 feet, then diamond cored to 4,371 feet, 28 feet of core being obtained for analysis. After logging by the U.S.G.S. District Groundwater Office in Atlanta, the well was terminated with 3/sup 1///sub 2/'' tubing to 4,386 feet. The bottom-hole temperature was determined to be 60/sup 0/C (140/sup 0/F) at 1,331 meters (4,365 feet). Over the interval 47 to 1,331 meters (154 to 4,365 feet) the least-squares temperature gradient was 29.3 +- 0.14 /sup 0/C/km (1.61 +- 0.25 /sup 0/F/100 ft)