Radioactive decay of granite and other rocks in Earth's interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.03 {\rm J} per kilogram each year. Find an increase in temperature for a thermally insulated chunk of granite that takes about 13.1 million years to change temperature. (Assume that the specific heat capacity c of granite is 800 {\rm J}/{\rm kg} \cdot {\rm C}^\circ. Use the equation Q =cm \Delta T.)