Scientists are creative people, bursting with theories, but a very small number of them are seized as if by viruses with all-encompassing theories that they just can't shake. Here's an assortment of wild Earth theories that have gripped the minds of educated people, some of them scientists. Don't worry, almost all of these are uninfectious. The newest entry is a variant of expanding-Earthism called "New Pangaea Theory." Like many geological pseudotheories, it's all about surface features with nothing to say about actual rocks or geologic history. And like a children's cartoon or classic monster movie, it's surprisingly eager to influence geo-history by flinging large space objects at the Earth.