Calculate the expected vertical profile of reaction progress in the case in which the variation is solely due to temperature (Arrhenius equation). Take the temperatures to be driven by sinusoidal variation at the surface over an annual cycle, the decay with depth being determined by the thermal diffusivity k = 1 mm²/s. Use the constants provided in the text for the universal gas constant and the activation energy of plagioclase-clay. How much higher will this chemical reaction rate be at 25°C than at 15°C?