A deep temperature-gradient drill hole drilled by Chevron Resources in the vicinity of Fox Mountain (Richards and Blackwell, 2002; SMU; Sass and others, 1999), about 16 km northwest of the Fly Ranch geothermal area, reported a near linear gradient of about 70 C/km. The maximum reported temperature was 218.7 C at a total depth of 1200 m (GeothermEx, 2004). Location: 41.02ºN, 119.56ºW.