It is believed that an orderly, even cyclic, process governs the formation and destruction of supercontinents. In the proposed theory, the dominant force is not the production of heat, but rather its conduction and loss through the earth's crust. Continental crust is only half as efficient as oceanic crust at conducting heat; thus, if a stationary supercontinent covers some part of the earth's surface, heat from the mantle should accumulate under the supercontinent, forcing it to dome upward and eventually break apart. As fragments of the supercontinent disperse, heat can be transferred through the new ocean basins formed between them. After a certain amount of heat has escaped, the continental fragments may be driven back together.