Terrestrial heat flow near Alberta, Virginia

Abstract

Temperatures were measured to a depth of 312 m in a hole cored in granite at 36°52.15′N, 77°54.15′W (elevation 116 m), near Alberta, Virginia. The temperature gradient in the lower half of the hole is uniformly 18°C/km. The cause of a variable gradient in the upper half of the hole is thought to be movement of groundwater within the hole. The average thermal conductivity determined from measurements on 0.64-cm-thick disks is 7.8 meal/cm sec °C, but the average conductivity computed by summing the thermal resistivities of the constituent minerals is 6.2. The corresponding values of heat flow are 1.4 and 1.1 μcal/cm2 sec, respectively. The average heat flow in eastern North America is 1.0, and the previously published high in this region is 1.3 μcal/cm2 sec.