Photo Three - Using what I had readily available, I covered the rock-face with kitchen towels laid over uPVA glue and then built up with more kitchen towels and uPVA glue in a paper-mache mix. The kitchen towels have a very distinct texture when built up in this way - one that mimics rock very well.
Photo Five - With the bulk of the groundwork now completed - the base is looking like a large piece of terrain or diorama. I have decided that I will use it as a 'back drop' for when I take photos of my finished Typhon project miniatures, It's too big to be used as a piece of stand-alone terrain, and too small to be used as a gaming board. However I am happy with it.