CompuServe Thread

Sorry I can't give you a usable reference, the topic is covered in many general geology texts, though. There were/are three sources of earth heat: 1. The planet accumulated stuff from solar nebula in its early stages of formation between 5 and 4.7 Ga (Gig-annum, billion years) and the kinetic energy turned into heat from the collisions was the earliest earth heat. 2. The heterogeneous proto-earth differentiated in its early history and the heavier constituents (the iron) fell to the core. That potential energy turned to heat probably melted the whole sheebang and blew off the first atmosphere. Most of it is still left. 3. Contained radioactive elements decay to produce heat. As I remember, there's enough radioactive potassium in the average granite to melt a piece in 25 million years if all of the heat produced could be contained in it and not lost. I dimly remember reading a paper by someone named Potopova (?) around 1970 who computed all the contributions to earth heat and she concluded that raadioactive decay balances heat lost from heat that flows slowly out through the normal crust and through volcanoes. Find a library that has GEOREF and search for earth heat.