I googled some of those links too, Crossjim, and of course my people are getting across the ones I didn't touch.
What struck me about them is that they weren't scientific theories at all, rather hypotheses, ideas or, to coin a phrase popularly applied to the ravings of former PM Tony Abbott - mere thought bubbles.
They typically used the vernacular meaning of the word theory because none were by definition scientific theory.
For instance, there was some theory around about Terra Australis, another about of Island of California but these were in fact mere ideas that had no basis whatsoever in reality.
Here's how Wikipedia describes the distinctly different meanings of the word.
It is important to note that the definition of a "scientific theory" (often ambiguously contracted to "theory" for the sake of brevity, including in this page) as used in the disciplines of science is significantly different from, and in contrast to, the common vernacular usage of the word "theory". As used in everyday non-scientific speech, "theory" implies that something is an unsubstantiated and speculative guess, conjecture, idea, or, hypothesis;[4] such a usage is the opposite of the word 'theory' in science. These different usages are comparable to the differing, and often opposing, usages of the term "prediction" in science (less ambiguously called a "scientific prediction") versus "prediction" in vernacular speech, denoting a mere hope."
Significance? For instance, the greenhouse gas effect can be repeatedly tested and confirmed. A theory about a global conspiracy of nearly all impartial scientists about anthropogenic global warming and climate change in order to feather their own nests is pie in the sky, just like David Icke's illuminati and shape shifting lizards.
