The overhead map in Total Miner is a map that shows the whole of the discovered terrain of the player. It is accessed by pressing the back button on the Xbox 360 Controller.
In Survival Mode, once the player opens the map, it will show all of the terrain currently explored by the player. area that have not been explored show as a blue area.
In Creative Mode, once the player opens the map, it will show the whole map, not just the area explored by the player.