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ABSTRACT
An energy balance shows that geomorphological processes are driven by an energy source more powerful than the geological processes that raise the continents. In addition, energy fluxes for the entire Earth are calculated from several energy sources including energy from the Sun, E^sub solar^, geothermal energy, E^sub geothermal^, based primarily on heat production from radiogenic sources, energy in the hydrologic cycle, E^sub hydrologic^, based on energy stored as latent heat in water vapor, and energy required to maintain continental uplift rates, E^sub potential^. The E^sub potential^ term is estimated from the hypsometric curve for the Earth's continents and the crustal roots according to Airy's model of isostasy. It is shown that E^sub solar^ > E^sub hydrologic^, E^sub geothermal^ > E^sub potential^ and E^sub hydrologic^ > E^sub potential^. The preceding calculations are presented in a format that illustrates the development and application of mathematical equations for geological problems. These examples provide instructors with material to illustrate the use of graphs, algebra and integral calculus in a geological context. All steps are explained assuming only basic knowledge from the reader.
Keywords: Energy balance, hydrologic cycle, isostasy, geothermal, geomorphology
INTRODUCTION
In geomorphology courses, landforms and the surface processes that produce them are closely examined while consideration of the energy that drives the processes is often given only cursory attention. For example, Ritter et al. (2002) stated that 2.4 X 10^sup 20^ calories of internal heat is transmitted to the Earth's surface each year (=3.2 X 1013 Watts), and noted that this was a small number compared to the energy input from the Sun, but they did not put this figure in a context of geomorphic significance, i.e. how much of this energy drives uplift? What component of the Sun's energy is used in denudation processes? Keller and Pinter (2002), in their book, Active Tectonics Earthquakes, Uplift, and Landscapes, never mentioned the driving forces for tectonics at all. Energy considerations were dealt with in somewhat more detail by Summerfield (1991), who presented a flow chart in which energy contributions from solar radiation (E^sub solar^ = 17.8 X 10^sup 16^ W), rotational energy of the solar system (E^sub rotational^ = 2.9 X 10^sup 12^ W) and geothermal heat flow (E^sub geothermal^ = 3.6 X 10^sup 13^ W)...