Erosion i think. erosion is when alot of things happen to the earth and they are all in some misshaped circle or cycle.for example and earth quake would make rocks go in the center of the earth(or in magma chambers)and come back out in a valcano and end up in the ocean of something then new earth after several years would rise and make mountians and the stuff that came out of the valcano would be there on the top of a mountian and maybe years later theres and avalanch and it ends up in the near by river. maybe that's sort of crazy but that's my most reasonable theory.