One major flaw most perpetual motion devices have is that they try to take energy from the force of gravity and then expect no forces of friction or a transfer of energy, so they are unable to bring parts of the device to an equal elevation as when they started. Then take a volcano for instance, dust and debris from a volcano can reach an elevation that is higher than where it started at. Then how is that possible? Well, volcanoes erupt from an increase and release of heat and pressure created from Earths gravity. The gravitation pull of the layers of rock sitting on top of each other will always be a constant pull that will always create more heat and pressure. This heat and pressure should then never go away. Therefore, volcanoes will continue to erupt indefinitely into the future. It is nothing that will ever stop. The core of the Earth will always remain hot. Then there should be a never ending cycle of volcano eruptions on Earth. Then why hasn't this ever been seen as an example of perpetual motion in nature?