The decision to drill deep holes in a prospective geothermal system implies that geothermal energy resources exist at depth. The drill hole location and budget result from hypothesis regarding the location and depth of the resource within the overall system. Although operational decisions normally dictate the practicality of drilling, the characteristics, we must first understand how unique various surface or shallow subsurface data are in assessing the nature of the resource. The following progress report summarizes the results of numerical simulations of heat and mass transport around igneous plutons and the synthesis of geologic data. To date, the results of the study describe the transient nature of thermal resources and the ambiguities which must be accounted for in using current technology to assess the nation's geothermal resources. [DJE-2005]