The book presents a full methodology for investigating heat flow and heat generation on a large scale (state). Detailed description of thermal conductivities measurements is given. Heat generation estimation is described. A thorough error analysis lends confidence to the final heat flow values. The book includes the first heat flow and heat generation maps of Oklahoma. The study is extended to the south central United States by incorporating additional heat flow data from neighboring states. Heat flow in Oklahoma appears to be consistent with that measured in other stable tectonic provinces of similar ages. The primary control on heat flow appears to be heat production in basement rocks, although it is difficult to establish a correlation because the heat flow and heat generation were measured at different sites. Factors such as tectonic transients and heat refraction appear to exert little influence on the present thermal regime. Although conduction seems to be the dominant mechanism of heat transport throughout the upper crust in most of Oklahoma, high heat flow in one section of east central Oklahoma may be related to regional groundwater flow.