if you want the image on every slide:
view > show master slides
click on the master slide being used
Inspector > slide > appearance > background > image fill - fit to fillnavigate to the image
if you want the image on a few slides:
click on the slide in the outline pane
Inspector > slide > appearance > background > image fill > fit to fill - navigate to the image
click on the slide in the outline pane then duplicate the slide ( command D) as many times as you need
Thanks, Gary. I did find a solution to the problem which I should have guessed earlier.
1. My relief map is my master slide, and all my graphics are simply copied from Adobe Illustrator where they are made.
2. My problem was the blink in the None transition, but I find that this is because I thought I had to have some type of Build chosen. This meant that my graphics had to await my master slide.
3. I now discovered that if I put on the graphics from the previous slice and leave my build for these graphics as "None" (and the transition at "None"), then they will appear with my master slide without a blink.
Thus I will try your suggestion above, but my immediate problem is solved. Many thanks!