Hi guys, longtime lurker. I've been playing around with a map for 4ish years in photoshop 7. Recently I've decided I want to expand the map. The map is based on the Saderan Tutorial posted here a few years ago (for reference if needed).

My WIP is divided into layers for land, grass, forest, desert, etc. So you've got the layer's color and then the black/white mask. I want to extend the canvas size out a further 10 inches and I know the current layers / mask will stop at the edge of the old size. How can I expand the layers to fill in the gap so I can continue working? I'm almost postive I knew how to do it when I first started working on the map but as I spend less time on it I've forgotten.

Thanks in advance.