Gas hydrate deposits: a primer

This graphic is a draft from an educational course I'm compiling about the Earth's natural gas reserves. It attempts to summarise what gas hydrates are and where they can be found, adn accompanies further graphics that explain the chemistry of hydrates. No attempt is made to quantify the amount of methane that might be present in these deposits globally - this is the subject of much uncertainty. Those interested in the details of resource size can refer to the sources listed in the graphic and GEA (2012). <em>Global Energy Assessment - Toward a Sustainable Future</em>. Cambridge University Press. I hope some will find this useful. Any comments, corrections and queries welcome.