In mainstream geology the Carboniferous (coal beds) were laid down 300 million years ago. At that time most of the ocean floor did not exist. Some of it did – but mostly, it didn't. What existed was a large continent, Pangeae, composed of all the major land masses of today – joined up. Some of this was covered by a shallow sea – it is thought. The Earth itself was much smaller according to Stephen Hurrell and due to the smaller size the gravity at the surface was much less than today. Life was massive – griant dragonlfies and millipedes, horsetails and club moss, amphibians larger than crocodiles, and all this was going on prior to the dinosaurs.
All sounds a bit interesting – is he on to something? Then he adds that mountains would have been much higher and as the Earth was smaller the poles were warm – lacking ice caps. Later, he claims the Ice Ages came about as a result of the expanding dimensions of the Earth. Hurrell's theory is therefore a mix of conventional with the idea of expansion of mass. Why not toss out all of mainstream thinking and start afresh? His idea is completely unlike the expanding earth theory as advocated by Tim Cullen at http://malagabay.wordpress.com where catastrophism is the trigger for episodic expansion.