Processes in the crust are driven by continuous supplies of energy from within the earth and from the sun. Natural reservoirs buffer and store that energy, and it is released periodically as geologic work. The tempo of geologic events is a function of the rate of energy input and the capacity and competence of the energy storage buffer. Buffers release energy at rates that range from catastrophic to gradual. External events can act as triggers, one event entraining another in its rhythm, but most geologic episodes are probably inherent in the processes that produce them. The concept of energy storage has general applicability to both the inorganic and organic world.